Dissertations / Theses on the topic 'Poly(acrylic acid)'
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Ling, Zichen. "ION EFFECTS ON SELF-HEALING POLY(ACRYLIC ACID) AND POLY(METHACRYLIC ACID) GELS." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1556767022932537.
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Kohen, Naomi (Naomi T. ). "Characterization of polystyrene-block-poly (acrylic acid) micelles." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32846.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005.Includes bibliographical references (leaf 38).
Several parameters that affect the formation, size and spatial distribution of micelles of poly(styrene-block-acrylic acid) (PS-b-PAA) in organic solvents or assembled on solid substrates have been investigated. The micelles were characterized in the solvated state using Dynamic Light Scattering, and were imaged and characterized in the dry thin film state using Atomic Force Microscopy. Micelle size in solution followed scaling laws based on the ratio of the two block copolymer segments. Micelle size was not affected by the addition of PS homopolymer or salt, whereas micelle diameter did increase with the addition of PAA homopolymer both in solution and in the dry state on sold supports. Furthermore, micelles formed in toluene, but they did not form in tetrahydrofurane, chloroform or hexane. In terms of spatial distribution in the dry state, the only parameters which affected spacing, and therefore density, were annealing conditions and addition of PAA homopolymer. Annealing near or below the glass transition temperature for 16 hours increased the order of the films, as was demonstrated by Fast Fourier Transforms of their AFM images. Annealing for longer periods of time or at temperatures significantly above the glass transition temperature destroyed the micelles.
by Naomi Kohen.
S.B.
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Chokalingam, Kumar. "Poly (Allylamine Hydrochloride) and Poly (Acrylic Acid) Multilayers for Gas Separation." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1187019230.
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Ofem, Michael. "Properties of chitin whisker reinforced poly(acrylic acid) composites." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/properties-of-chitin-whisker-reinforced-polyacrylic-acid-composites(dd295cc1-3972-4544-be7d-9e80fafe5d19).html.
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Composites, in which the matrix and the reinforcing fillers are respectively, poly(acrylic acid) (PAA) with two different molecular weights, and chitin whiskers (CHW) were successfully prepared using an evaporation method. The weight fraction of CHW was varied from 0.03 to 0.73. Mechanical and thermal properties and crystallinity of the composites were characterised using tensile testing, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. The tensile strength of the composite increased up to 11 wt % CHW after which it decreased. XRD characterisation showed a decrease in crystalline index, crystalline size, chitin crystalline peak and intensity as the content of PAA and its molecular weight increased. Raman spectroscopy was used for the first time to monitor the deformation of chitin film and CHW reinforced PAA composites. The Raman band located at 1622 cm^(-1) was monitored for deformation. On application of tensile deformation the Raman band initially located at 1622 cm^(-1) shifted toward a lower wavenumber. Raman band shift rates of -1.85 cm^(-1)/% for chitin film and -0.59 and -0.25 cm^(-1)/% for 73 and 23 wt % CHW content, respectively, were measured. The modulus of a single chitin whisker and composites were found to be 115, 37 and 16 GPa respectively, for a two dimensional (2D) in-plane distribution of CHW. CHW within a PAA matrix did not show any preferential alignment in a polarised Raman. The Raman intensity ratio〖 I〗_1698 /I_1622 showed that the strongest interaction of the carboxylic group in the composites occured at 3 wt % CHW content. The interaction gradually reduced as the CHW content increased. 〖 CaCO〗_3 crystals were grown in CHW, PAA and CHW/PAA composites by a solution and evaporation casting method. In the absence of PAA and CHW, rhombohedral calcites were observed while rod-like aragonite polymorphs were seen when only PAA was used as a template. In the presence of only CHW, a morphological mixture of ellipsoidal and disc shape with traces of rhombohedral aggregate calcite were the features. In the presence of both PAA and CHW, the rhombohedral shape showed roughness with irregular faces while the vaterite polymorph continued to agglomerate with the observation of porosity at higher CHW content. The vaterite particles gradually decreased as the CHW content was decreased. At lower CHW content aragonite polymorph growth was favoured to the detriment of calcite. The results showed that the vaterite polymorph can be grown even at higher filler loading. The effect of 〖 CaCO〗_3 growth on the mechanical properties of CHW reinforced PAA indicated that better mechanical properties can be achieved at a CHW content of 3 wt % when compared with neat PAA and when 〖 CaCO〗_3 was not incorporated into the CHW/25PAA composites.
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El-Anani, Anas. "Pervaporation dehydration of isopropanol/water using poly(hema)/poly acrylic acid composite membranes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0019/MQ58451.pdf.
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Swinyard, B. T. "Multiple phase equilibria in polar polymer solutions containing poly(acrylic acid)." Thesis, University of Stirling, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370518.
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Doungsong, Nettraporn. "Synthesis and characterization of poly(acrylic acid) based microgels for formulation applications." Thesis, University of Bristol, 2018. http://hdl.handle.net/1983/93083012-600c-42a8-8a53-88e08505b22b.
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pH-responsive microgels are cross-linked polymer particles which can swell/deswell in response to pH and salt concentration of their external surroundings. This project focuses on the pH-responsive microgels particularly based on poly(acrylic acid) (PAA) hydrophobically modified with poly(ethers) i.e. poly(propylene glycol) (PPG) and poly(tetrahydrofuran) (PTHF). Interestingly, these poly(ethers) are not widely used to incorporate in PAA based hydrogels yet. We expect that these microgels might be further used as carriers for both hydrophilic and hydrophobic active ingredients with controlled-release response triggered by pH and salt concentration. With chemical cross-linking, we prepared well-defined PAA micro-spherical hydrogels cross-linked with either PPG- or PTHF-divinyl acrylate end groups via surfactant free emulsion polymerization and acid-hydrolysis. The chemical structure of the microgels was confirmed by FT-IR and NMR. At high pH, electrostatic repulsion between ionized carboxyl groups of PAA contributed to the swelling of the microgels. Moreover, the shape factor (ρ = RG/RH) obtained by DLS and SLS informed that the microgels contain a dense core with a loose shell. Additionally, physical association between PAA and poly(ethers) in solutions was investigated using various techniques. Whilst 1H-NMR does not appear to be too helpful to detect polymer association, DOSY-NMR already provided indications for the association at low Mw but T2 solvent relaxation approach required higher Mw samples for a clear effect to be visible. Furthermore, we performed preliminary experiments using a dialysis method and UV-Vis spectroscopy to investigate the release of active ingredients (AIs; benzyl alcohol and paracetamol) from Carbopol® 690, commercial PAA hydrogels, as a function of pH. The results show that the release of AIs was significantly sustained comparing with the control samples. However, the effect of pH (or the swelling of Carbopol®) on the release of AIs is rather unclear.
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Wu, Qinghua 1977. "Self-assembly of poly(ethylene oxide)-b-polystyrene-b-poly(acrylic acid) triblock copolymers in solution." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98522.
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The self-assembly behavior of poly(ethylene oxide)-b-polystyrene- b-poly(acrylic acid) (PEO-b-PS-b-PAA) triblock copolymers in solution is the focus of this thesis. The triblock copolymers were synthesized by atom transfer radical polymerization (ATRP). The compositions of the block copolymers were determined by 1H NMR. The synthesized block copolymers have relatively low polydispersity indexes (PDI < 1.3) as proved by GPC. The influence of several factors on the ATRP of styrene or t-BA, such as temperature, catalyst and polymerization time, was also explored. The effects of several parameters on the self-assembly behavior of this triblock copolymer were investigated, including the nature and composition of the common solvent, PAA block length, pH, water content, and initial copolymer concentration. Multiple morphologies, such as spheres, vesicles, lamellae and rods have been prepared by varying the above parameters. In particular, vesicles with either PEO or PAA outside have been successfully prepared in dioxane/water. These vesicles may serve as carriers for potential encapsulation applications. The average size and corona chain composition of the triblock copolymer vesicles can be controlled by varying factors such as the PAA block length and pH. The polymer chains may have different arrangements in the vesicle wall, resulting in different corona chain compositions. The vesicles with PAA outside are stable in water, while the vesicles with PEO outside tend to flocculate. Nevertheless, the sediment can be redispersed under vigorous stirring.
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Crouch, Stephen Wallace. "The synthesis and study of poly(N-isopropylacrylamide)/poly(acrylic acid) interpenetrating polymer network nanoparticle hydrogels." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5382/.
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Homogeneous hydrogels made of an interpenetrating network of poly(N-isopropylacrylamide) (PNIPAm) and poly(acrylic acid) (PAAc) are synthesized by a two-step process; first making PNIPAm hydrogels and then interpenetrating acrylic acid throughout the hydrogel through polymerization. The kinetic growth of the IPN is plotted and an equation is fitted to the data. When diluted to certain concentrations in water, the hydrogels show reversible, inverse thermal gelation at about 34°C. This shows unique application to the medical field, as the transition is just below body temperature. A drug release experiment is performed using high molecular weight dyes, and a phase diagram is created through observation of the purified, concentrated gel at varying concentrations and temperatures.
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Theqah, Ameerah Mohammed. "Conformational studies of poly(2-(dimethylamino ethyl methacrylate)) (PDMAEMA) and poly(acrylic acid) (PAA) using fluorescence spectroscopy." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/15512/.
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This project aims to explore the aqueous solution dynamics of the poly(dimethyl aminoethyl methacrylate) (PDMAEMA) and poly(acrylic acid) (PAA) systems using fluorescence techniques. Both of these polymers were synthesised several times using free radical polymerisation techniques with two types of fluorophore labels included in synthesis. The resultant polymers were investigated using fluorescence techniques which include steady state fluorescence studies, fluorescence decay lifetimes and time resolved anisotropy measurements. Initial solution dynamics of these polymer show that the PDMAEMA exhibits a coiled conformation at high pH values and adopts an expanded form at low pH values. PAA exhibits a partially coiled form at low pH values, but adopt a relatively expanded chain at a pH approximately more than their pKa. The study also shows that the pendant amine groups of the PDMAEMA polymer effect the fluorescence of the labels, and this is what is observed at high pH. Addition of salts to PAA polymer promote coiling at low and high pH except salt of NaCl and CaBr2. When they added to the uncharged polymer, where it cause the polymer chain to flatten at low concentration of salt, and then to fold again under further addition of these salts. Effect of salts on PDMAEMA polymer conformation has been found to be efficient in growth of aggregation for the cationic polymer. However, salts like sodium chloride, sodium bromide and calcium bromide, has a different effect on the polymer conformation which exist in a coiled state, as they unfold the coiled polymer (at high pH) at low concentrations of them and refold it at high concentration. The interactions between polyelectrolytes and the oppositely charged surfactant micelles have been investigated using fluorescence technique, in order to understand the conformation and the dynamics of these polyelectrolytes. Addition of cationic micelles (CTAC) to anionic PAA polymer (at high pH), and anionic micelles(SHS) to cationic PDMAEMA polymer(at low pH), change the conformation form of the polymers from an expanded chains to a collapsed structure, as the electrostatic forces assume to play the main role in such interactions. Whereas, the hydrophobic forces control the interactions in polymer/micelles system when the polymers adopt a coiled conformation.
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Canning, Sarah. "Poly(alkyl methacrylate-co-acrylic acid) copolymers of varying architecture for improved adhesion." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/10388/.
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Amphiphilic copolymers composed of hydrophilic polyacrylic acid segments and hydrophobic poly(alkyl methacylate) segments were targeted as adhesion-promoting additives for use in printing inks. Methyl, butyl and lauryl methacrylates were chosen to vary hydrophobicity. Initially, a phase transfer-catalysed backbone functionalisation and a reversible addition-fragmentation chain transfer (RAFT)-controlled grafting step were employed to form graft copolymers, although polyacrylic acid homopolymer was also produced. The lauryl methacrylate synthesis proved more difficult due to the steric effect of the long alkyl chain. Branched and linear poly(alkyl methacrylate-acrylic acid) copolymers were then synthesised using RAFT, in either a one-pot polymerisation, producing random copolymers, or a two-step procedure forming block copolymers. Molecular weights of close to 20 000 g mol-1 were achieved, with methacrylate:acrylic acid ratios close to 1:1, as targeted. Branching was confirmed through calculation of Mark-Houwink parameters using GPC with viscometric detection, and a 13C NMR method was developed to identify block or random monomer sequence distribution. Due to their amphiphilic nature, the copolymers were found to self-assemble in water to form macromolecular structures. These varied according to architecture, monomer distribution, and hydrophobicity of the methacrylate segment. Small angle neutron scattering was used to study the copolymers in a range of solvent systems. Whilst Gaussian coils were formed in d-THF and self-assembled spheres or multi-lamellar micelles were formed in D2O, the copolymers were found to aggregate into fractal structures in intermediate solvency conditions. The behaviour of the copolymers when coated on polyolefin substrates was studied by contact angle measurements, and the random materials created more polar surfaces compared to the segmented analogues. A force spectroscopy technique showed potential for accurate comparison of copolymer adhesion. Ink formulations containing the butyl methacrylate copolymers jetted well on both thermal inkjet and drop on demand printers. Adhesion was assessed using industry standard tests, and better overall performance was observed for the branched copolymers.
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Zhang, Lifeng. "Crew-cut aggregates of polystyrene-b-poly(acrylic acid) diblock copolymers in solutions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0008/NQ30429.pdf.
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Zhang, Lifeng. "Crew-cut aggregates of polystyrene-b-poly (acrylic acid) diblock copolymers in solutions." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34489.
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The morphological characteristics of highly crew-cut micelle-like aggregates of asymmetric polystyrene-b-poly(acrylic acid) copolymers PS-b-PAA, was studied by transmission electron microscopy and light scattering. The insoluble PS block contents in the copolymers ranged from 80 to 98 wt. %. The aggregates were formed by the water addition to the copolymer solution in N,N-dimethylformamide, and then were isolated in aqueous solutions.Spherical micelles were formed when the PAA content in the copolymers was relatively higher. The PS core radii scaled as R$ sb{ rm core} sim$ N$ sb{ rm PS} sp{0.4}$ N$ sb{ rm PAA} sp{-0.15}$, where N$ sb{ rm PS}$ and N$ sb{ rm PAA}$ are the lengths of the PS and PAA blocks, respectively. The PAA corona shell dimensions were also studied. As the PAA content in block copolymers decreased, the morphology of the aggregate changed progressively from spheres to cylinders, to vesicles and lamellae, and eventually to compound micelles. The effects of the initial copolymer concentration and the addition of homopolystyrene on the aggregate morphology were also examined. The aggregate morphology appears to be controlled by a force balance mainly involving three aspects, i.e. the stretching of the PS chains in the core, the surface tension between the PS core and the solvent, and the inter-corona chain interactions.
The aggregate morphology can be controlled by adding ions in micro-molar (HCl, NaOH, CaCl$ sb2$ or Ca(Ac)$ sb2$) or milli-molar (NaCl) concentrations. In addition to the various morphologies obtained by changing the copolymer composition, large compound vesicles, a new morphology, can be obtained from a single block copolymer. The morphogenic effect of different added ions on the crew-cut aggregates can be ascribed to the changed inter-corona chain repulsive interactions, due to neutralization, protonation, ion-binding, and screened electrostatic field, etc. The range of morphologies obtained in this study is believed to be unprecedented for a block copolymer self-assembly system in low molecular weight solvents.
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Dey, Rebecca. "An investigation into the potential use of poly(vinylphosphonic acid-co-acrylic acid) in bone tissue scaffolds." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/an-investigation-into-the-potential-use-of-polyvinylphosphonic-acidcoacrylic-acid-in-bone-tissue-scaffolds(0f3b96dd-29e6-4b46-9760-57770dee8bde).html.
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Bone undergoes constant turnover throughout life and has the capacity to regenerate itself. However, the repair of critical size defects, caused by bone diseases such as osteoporosis, can be more problematic. Therefore, there is a clinical need for a bone graft substitute that can be used at sites of surgical intervention to enhance bone regeneration. Poly(vinylphosphonic acid-co-acrylic acid) (PVPA-co-AA) has recently been identified as a potential candidate for use in bone tissue scaffolds. It is hypothesised that PVPA-co-AA can mimic the action of bisphosphonates â a class of drugs used in the treatment of osteoporosis â by binding to calcium ions from bone mineral surfaces. In this way, bisphosphonates can affect bone turnover by increasing the activity of osteoblasts and reducing osteoclast activity. Although PVPA-co-AA has been shown to improve bone formation, the mechanism of action has so far not been fully elucidated. Therefore, this work aims to understand the effect of copolymer composition on the properties of PVPA-co-AA, and thus to determine its effect on osteoblast adhesion and proliferation. PVPA-co-AA copolymers have been synthesised with a range of monomer feed ratios. It was found that a VPA content of 30 mol % led to the greatest calcium binding affinity of the copolymer and is thus expected to lead to enhanced bone formation and mineralisation of the matrix produced by osteoblast cells. The release profile of PVPA-co-AA from electrospun PCL scaffolds was investigated. It was shown that all of the PVPA-co-AA was released into aqueous media within 8 h of immersion. It was also found that the calcium chelation from osteogenic differentiation media significantly increased within the first 8 h. Therefore, it was concluded that PVPA-co-AA is released from the scaffolds, where it can then bind to calcium ions from the bone mineral surface to promote mineralisation, thus acting as a mimic of non-collagenous proteins, which are present in the extracellular matrix (ECM) of bone. Hydrogels of PVPA-co-AA have been produced and the effect of monomer feed ratio (0-50 mol % VPA) on the properties of the gels was explored. It was found that an increase in VPA content led to greater hydrogel swelling and increased porosities. Hydrogels that contained 30 and 50 mol % VPA were shown to have similar morphologies to the native ECM of bone. Rheological testing showed that hydrogels with higher VPA contents were more flexible and could be deformed to a large extent without permanent deformation of their structure. An increase in osteoblast adhesion and proliferation was observed for hydrogels with 30 and 50 mol % VPA content as well as superior cell spreading. Osteoblast cell metabolic activity also increased as a function of VPA content in the hydrogels. This work indicates that hydrogels of PVPA-co-AA, with VPA contents of 30 or 50 mol %, are ideal for use as bone tissue scaffolds. Furthermore, the mechanical and cell adhesion properties of the gels can be tuned by altering the copolymer composition. Finally, composite hydrogels of PVPA-co-AA and hydroxyapatite (HA) have been produced and investigated for their ability to remove fluoride ions from groundwater. It was found that the fluoride uptake ability of PVPA-HA hydrogels was significantly enhanced when compared with HA powder alone. Furthermore, the fluoride uptake was dependent on many factors, including pH, contact time and the presence of competing ions. It was possible to regenerate the hydrogel to remove the fluoride ions, and thus it was shown that the material can be used a number of times with only a slight reduction in its fluoride uptake capacity.
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Tobiesen, Finn Andrew. "A method for grafting poly(acrylic acid) onto nylon 6,6 using amine end-groups on the nylon surface." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/29994.
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Chijiwa, Sachiko. "Characterization of polystyrene-b-poly(acrylic acid) copolymer micelles by nuclear magnetic resonance spectroscopy." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32983.
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This dissertation describes the characterization of polystyrene- b-poly(acrylic acid) (PS-b-PAA) copolymer micelles by nuclear magnetic resonance spectroscopy (NMR). The segmental chain dynamics of the polystyrene-b-poly(acrylic acid) copolymer during the micellization process was investigated by solution-state proton NMR measurements. The spin-lattice and spin-spin relaxation parameters revealed the increased motional restriction of the PS blocks of the PS-b-PAA copolymer as aggregation was induced. The mobility of the PAA segments also decreased during the micellization process. However, the PAA blocks experienced greater motional freedom than the PS component forming the aggregate core.129Xenon NMR spectroscopy was used to determine the glass transition temperature of the PS core of the polystyrene-b-poly(acrylic acid) copolymer aggregates in dioxane/water mixtures. The temperature dependence of the NMR line shapes and resonance shifts of xenon in the PS and solvent phases of the PS-b-PAA copolymer micelles was analyzed. Discontinuities in the slope of the chemical shift-temperature curves for xenon sorbed in the PS component revealed phase transitions in the copolymer micelles. The PS core of the phase separated PS100-b-PAA 25 copolymer aggregates underwent the glass transition in the temperature region of 40°C to 45°C. The glass transition temperature of the PS core of PS218-b-PAA20 copolymer aggregates suspended in solution was in the 33°C to 35°C temperature region.
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Zhou, Bo. "Synthesis and characterization of crystalline assembly of poly Nisopropylacry-lamide)-co-acrylic acid nanoparticles." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4671/.
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In this study, crystalline poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAm-co-AAc) nanoparticle network in organic solvents was obtained by self assembling precursor particles in acetone/epichlorohydrin mixture at room temperature followed by inter-sphere crosslinking at ~98 °C. The crystals thus formed can endure solvent exchanges or large distortions under a temporary compressing force with the reoccurrence of crystalline structures. In acetone, the crystals were stable, independent of temperature, while in water crystals could change their colors upon heating or changing pH values. By passing a focused white light beam through the crystals, different colors were displayed at different observation angles, indicating typical Bragg diffraction. Shear moduli of the gel nanoparticle crystals were measured in the linear stress-yield ranges for the same gel crystals in both acetone and water. Syntheses of particles of different sizes and the relationship between particle size and the color of the gel nanoparticle networks at a constant solid content were also presented. Temperature- and pH- sensitive crystalline PNIPAm-co-AAc hydrogel was prepared using osmosis crosslinking method. Not only the typical Bragg diffraction phenomenon was observed for the hydrogel but also apparent temperature- and pH- sensitive properties were performed. The phase behavior of PNIPAm nanoparticles dispersed in water was also investigated using a thermodynamic perturbation theory combined with lightscattering and spectrometer measurements. It was shown how the volume transition of PNIPAM particles affected the interaction potential and determined a novel phase diagram that had not been observed in conventional colloids. Because both particle size and attractive potential depended on temperature, PNIPAM aqueous dispersion exhibited phase transitions at a fixed particle number density by either increasing or decreasing temperature. The phase transition of PNIPAm-co-AAc colloids was also studied. The results from the comparison between pure PNIPAm and charged PNIPAm colloids showed that the introducing of carboxyl (-COOH) group not only contributed to the synthesis of three-dimensional nanoparticle network but also effectively increased the crystallization temperature and concentration range. The phase transitions at both low and high temperatures were observed from the turbidity change by using UV-Vis spectrometer. Centrifugal vibration method was used to make crystalline PNIPAm-co-AAc dispersion at high concentration (8%). The turbidity test proved the formation of iridescent pattern.
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Zafar, Syed Muhammad Sohaib Zafar. "Differential Association of Vitronectin and Fibronectin with Glass and Electrospun Fibers of a Poly (D-Lysine) /Poly (Acrylic Acid)." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6444.
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Proteins represent major constituent of the extracellular matrix which plays an important role in the formation, maintenance and remodeling of tissues, this project focuses on adsorption of two specific serum proteins fibronectin (FN) and vitronectin (VTN) responsible for mediating cell matrix interaction through integrin binding, tripeptide Arg-Gly-Asp (RGD) sequence found in these protein features are recognized by αβV3 integrin which ultimately helps in clot formation.
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Meinderink, Dennis [Verfasser]. "Molecular adhesion science and engineering of nanostructured poly(acrylic acid)/metal oxide interfaces / Dennis Meinderink." Paderborn : Universitätsbibliothek, 2020. http://d-nb.info/1226852726/34.
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Siyambalagoda, Gamage Pubudu Hasanka. "Synthesis and applications of ruthenium(II)quaterpyridinium complexes and Poly-N-isopropylacrylamide/ acrylic acid copolymers." Diss., Kansas State University, 2009. http://hdl.handle.net/2097/4621.
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Doctor of PhilosophyDepartment of Chemistry
Stefan Bossmann
Tris-homoleptic ruthenium(II)-quaterpyridyl and quaterpyridinium complexes, with +8 and +14 charge were synthesized by utilizing high pressure reaction pathway. These complexes have diameters ranging from 1.82 to 4.55 nm according to the molecular modeling calculations. These ruthenium complexes are highly luminescent and contain long excited state life times. The novel ruthenium(II)-quaterpyridinium complexes exhibit superior reactivity as sensitizer-relay-assemblies (SRA‟s) in sacrificial systems for water and carbon dioxide reductions, while harvesting the ultraviolet- and most of the visible fraction of the incident solar spectrum. Ru(II)-quaterpyridinium complexes and Pd/TiO2 catalysts were successfully used as the catalytic system for the photo catalytic reduction of water and carbon dioxide to hydrogen and methane respectively. Phosphonate-tethered Ru(II)-quaterpyridinium complexes were synthesized from Ru(II)-tris-quaterpyridyl complexes. These complexes form stable adhesive layers on indium tin oxide (ITO) electrodes. A series of differential pulse voltammetry experiments were carried out to measure the ground state and excited state redox potentials of all the Ru(II)quaterpyridinium complexes. The reductive potentials obtained were compared with the reductive potentials of CO2 to CH4 and H2O to H2 reductions. The measurements obtained from the experiments confirmed that it is possible to thermodynamically oxidize water and reduce CO2 by using phosphonate-tethered Ru(II)-quaterpyridinium complexes. These complexes are successfully utilized as prototypes for mycobacterial channel blockers. The Ru(II) complexes show distinct changes in their luminescence spectra when bound to the porin MspA from M. smegmatis, which is a non-pathogenic relative of M. tuberculosis. By using HPLC, we have determined binding constants of the Ru(II)-complexes to MspA in phosphate buffer (0.05 M, pH = 6.8) ranging from 5.2 x 109 M-1 (Ru-C2) to 1.8 x 109 M-1 (Ru-C4). Our findings indicate that channel blocking is a promising treatment strategy for mycobacterial infections. Poly-N-isopropyl-acrylamide/acetic acid copolymers were synthesized and characterized by elemental analysis and gel permeation chromatography. The average composition of the copolymers determined from CHN analysis is in excellent correlation with the feed composition indicating that the radical polymerization process is indeed statistical. Crosslinking of individual polymer chains permitted the generation of ultraflat layers on Mica surfaces by a simple spin-casting procedure, which are able to host the mycobacterial channel protein MspA, while retaining its channel function.
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Pinardag, Fatma Esra. "Modified Acrylic Hydrogels As Controlled Release Systems." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607362/index.pdf.
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In this study, pH-sensitive poly(acrylamide-co-acrylic acid) hydrogels were synthesized as controlled release systems in the presence of N,N-methylene bisacrylamide as crosslinker and ammonium persulfate as initiator. A set of hydrogels were used in the form they were prepared. One set of hydrogels were prepared as porous networks by incorporating sodium chloride into the reaction medium and then leaching of it after the completion of polymerization reaction. Two sets of hydrogels were modified by argon-plasma at different discharge powers. Hydrogels were characterized by 13C-NMR, XPS, SEM, ATR-FTIR, ESR as well as equilibrium degree of swelling (EDS) and contact angle measurements. Prepared hydrogels were loaded with a model antibiotic, ciprofloxacin-HCl (CPFX), and in-vitro release of CPFX from hydrogel matrices were examined in buffer solutions of varying pH values. There are two factors determining the release rates of CPFXone is the pH-dependent solubility of CPFX and the other is EDS of the hydrogel samples. For porous samples drug loading and release rates were higher when compared to the control samples and CPFX solubility dominated over release kinetics. Plasma treatment resulted in prolonged release rates in acidic medium.
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Phathekile, Bonke. "Synthesis of peptide-loaded chitosan nanoparticles for the treatment of sexually transmitted infections (STI’s)." University of Western Cape, 2019. http://hdl.handle.net/11394/7726.
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>Magister Scientiae - MScPeptides are among the main drugs which attract much attention because of their great potential in treating sexually transmitted diseases and other chronic diseases. There has been a major challenge of delivering these drugs in mucosal sites with low pH environment. The aim of this study is to synthesize acidic pH stable peptide loaded chitosan nanoparticles gels that could penetrate mucus layers covering the epithelial cells and kill HIV virus. Chitosan nanoparticles were synthesized by crosslinking method called Ionic gelation with Sodium tripolyphosphateTPP.
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Hu, Nan. "Block and Graft Copolymers Containing Carboxylate or Phosphonate Anions." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/70877.
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This dissertation focuses on synthesis and characterization of graft and block copolymers containing carboxylate or phosphonate anions that are potential candidates for biomedical applications such as drug delivery and dental adhesives.
Ammonium bisdiethylphosphonate (meth)acrylate and acrylamide phosphonate monomers were synthesized based on aza-Michael addition reactions. Free radical copolymerizations of these monomers with an acrylate-functional poly(ethylene oxide) (PEO) macromonomer produced graft copolymers. Quantitative deprotection of the alkylphosphonate groups afforded graft copolymers with zwitterionic ammonium bisphosphonate or anionic phosphonate backbones and PEO grafts. The zwitterionic copolymers spontaneously assembled into aggregates in aqueous media. The anionic copolymers formed aggregates in DMF and DMSO, while only small amounts of aggregates were present in copolymer/methanol or copolymer/water solutions. Binding capabilities of the acrylamide phosphonic acids were investigated through interactions with hydroxyapatite.
Previously our group has prepared poly(ethylene oxide)-b-poly(acrylic acid) (PEO-b-PAA) copolymers and used these polymers as carriers for both MRI imaging agents and cationic drugs. To enhance the capabilities of those carriers in tracking and crosslinking, we have designed, synthesized and characterized amine functionalized PEO-b-PAA copolymers. First, heterobifunctional poly(ethylene oxide) (PEO) with three different molecular weights were synthesized. Modification on one of these afforded a PEO macroinitiator with a bromide on one end and a protected amine on the other end. ATRP polymerization of tert-butyl acrylate (tBuA) in the presence of this initiator and a copper (I) bromide (CuBr) catalyst yielded a diblock copolymer. The copolymer was deprotected by reaction with trifluoroacetic acid (TFA) and formed an amine terminated H2N-PEO-b-PAA.
Recently our group has utilized the novel ammonium bisdiethylphosphonate (meth)acrylate and acrylamide phosphonate copolymers to incorporate Carboplatin. The resulting complexes exhibited excellent anticancer activity against MCF-7 breast cancer cells which might be related to ligand exchange of the dicarboxylate group of Carboplatin with the phosphonic acid moieties in the copolymer. Hence, complexation of small-molecule phosphonic acids with Carboplatin was investigated. Three compounds, vinylphosphonic acid, 3-hydroxypropyl ammonium bisphosphonic acid and 2-hydroxyethyl ammonium phosphonic acid were complexed with Carboplatin under acidic and neutral conditions. Covalent bonding of these acids to carboplatin was only observed under acidic pH. The covalently bonded percentage was 17%, 37% and 34%, respectively. More in-depth investigation was of great importance to further understand this complexation behavior.Ph. D.
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Permyakova, N. M., T. B. Zheltonozhskaya, V. I. Maksin, V. G. Kaplunenko, and O. V. Revko. "Block Copolymers Containing Poly(acrylic acid) for Stabilization of Vitamin E and Silver Nanoparticles in Aqueous Solutions." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34943.
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We have synthesized asymmetric di- and triblock copolymers containing chemically complementary
blocks of poly(acrylic acid) and methoxypoly(ethylene oxide) (PAAc-b-MOPEO) or poly(ethylene oxide)
(PAAc-b-PEO-b-PAAc) using a template radical block copolymerization process. At low pH, polyacid blocks
of these copolymers were protonated and formed the intramolecular polycomplexes (IntraPCs) with
MOPEO or PEO blocks. Due to both the intramolecular complex formation and hydrophobic interactions
between non-polar bound segments of the blocks, an intensive micellization in copolymer solutions at low
pH took place. Aqueous copolymer solutions were used as nanocontainers for encapsulation of poorly soluble vitamin E and as nanoreactors for the silver nanoclusters/nanoparticles formation.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34943
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Terreau, Owen L. "The effect of block molecular weight distribution on morphologies of polystyrene-block-poly (acrylic acid) aggregates in solution /." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85098.
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The effect of the molecular weight distribution of both the soluble and the insoluble blocks on the solution self-assembly of the amphiphilic block copolymer polystyrene-block-poly(acrylic acid) was studied. Copolymers of a variety of block lengths but with narrow molecular weight distributions were synthesized by sequential anionic synthesis. Mixing two or more copolymers of differing block length (while the second block length was identical) artificially increased the polydispersity index (PDI) of one block. Self-assembly was induced by adding water slowly to a copolymer solution until a desired solvent composition was attained. The resulting aggregates were compared using transmission electron microscopy and dynamic light scattering.The first experiments, presented in chapter 2, studied the effect of the corona (PAA) polydispersity on the size of vesicular aggregates. For a constant solvent composition and copolymer concentration, the size of the vesicles was generally found to decrease with increasing PAA polydispersity. In chapter 3, a partial phase diagram of morphology as a function of water content and PAA polydispersity is presented. The phase boundaries between spheres and rods, and rods and vesicles were found to shift to lower water contents with increased PAA polydispersity.
While chapters 2 and 3 show that the PAA polydispersity affects both the morphology and the size of vesicles, chapter 4 presents work that indicates that the shape of the PAA molecular weight distribution plays an important part in determining the degree to which the PAA polydispersity affects the morphology. A subsequent study also shows that the molecular weight distribution effect only occurs when the relative PAA/PS block length ratio is low.
The polystyrene molecular weight distribution studies, presented in chapter 5, show that the opposite effect to that of the PAA molecular weight distribution occurs with an increase in the PS PDI. The morphological boundary from spheres to rods was found to move to higher water contents with an increase in PS PDI. Even at very high water contents, where vesicles are usually found for low molecular weight distribution samples, only spherical micelles were found for the samples with increased PS PDI.
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Ziyuan, Gong. "EFFECT OF SODIUM DODECYL SULFATE ON THE STRUCTURE AND RHEOLOGICAL PROPERTIES OF PLURONIC F108 - POLY(ACRYLIC ACID) COACERVATES." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1555681739197109.
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Hu, Kang Dickson J. M. "Development and characterization of poly(vinylidene fluoride)-poly(acrylic acid) pore-filledpH-sensitive membranes and potential application on controlled drug release for ruminant animals." *McMaster only, 2007.
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Choucair, Amira. "Kinetics of fusion, conrol of size, and active loading into polystyrene-♭-poly(acrylic acid) vesicles by Amira Choucair." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84494.
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Polystyrene-b-poly(acrylic acid) block copolymers can self-assemble in selective solvents to form aggregates of different morphologies, including spherical micelles and vesicles. The ability of spherical micelles to solubilize (incorporate) 2-nitrodiphenylamine, a model hydrophobic but polar dye molecule, is investigated. The solubilization capacity of the micelles is evaluated as a function of the dye concentration, and the results are explained by treating solubilization as an adsorption process. The location of the incorporated molecules within the micelle is also examined, and the interfacial region of the micelle is identified as the solubilization site. Vesicles prepared from polystyrene-b-poly(acrylic acid) in dioxane/water mixtures undergo fusion (and therefore increase in size) as the water content in the solvent mixture increases. The kinetics of this process is followed, and the evaluated relaxation times range between 10 and 700 s, depending on the solvent composition, the amount of water added, the polymer concentration, and the poly(acrylic acid) block length. In addition, the preparation of vesicles with tunable sizes is examined. Additives (such as NaCl, HCl, and NaOH), as well as the solvent composition (ternary mixtures of water/dioxane/THF) are used to vary the diameter of vesicles prepared from the same copolymer. The effect of poly(acrylic acid) block length on vesicles size is also determined. Finally, polystyrene- b-poly(acrylic acid) vesicles are used as model carriers for the anti-tumor drug, doxorubicin hydrochloride. A pH-induced, active loading method is applied to concentrate the drug into the aqueous cavity of the vesicles.
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Pethe, Vishwas Vyankatrao. "Oxygen and Carbon Dioxide Permeability of EEA/PEO Blends and Microlayers." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1196374484.
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Thürmer, Monica Beatriz. "Alfa-fosfato tricálcico obtido por reação via úmida para aplicação em cimentos ósseos e cimentos compósitos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/159263.
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Nos últimos anos, intensos estudos vêm sendo realizados no que se refere a substitutos ósseos biocompatíveis e absorvíveis, notadamente os cimentos ósseos de fosfato de cálcio, para cirurgias de reconstrução e em engenharia de tecidos. Porém os cimentos de fosfato de cálcio desenvolvidos apresentam baixa resistência mecânica quando comparados com os ossos do corpo humano. Neste contexto, a busca por alternativas para minimizar esse problema tem se intensificado. A obtenção de alfa-fosfato tricálcico por outras rotas de síntese, bem como o desenvolvimento de compósitos de fosfatos de cálcio e hidrogéis têm se destacado nesse ramo. O preparo destes compósitos permite combinar excelentes propriedades como: i) osteocondutividade e capacidade de formar ligações com o tecido ósseo proporcionado pelos fosfatos de cálcio e ii) facilidade de adesão e distribuição de células no interior de scaffolds, proporcionado pelo hidrogel. O objetivo do presente trabalho foi o desenvolvimento de uma nova metodologia de obtenção de alfa-fosfato tricálcico, o preparo de composições de cimentos de fosfato de cálcio e de hidrogéis, bem como a obtenção e caracterização de compósitos destes, visando o melhoramento das propriedades para aplicação como biomaterial Foi possível sintetizar alfa-fosfato tricálcico com elevado grau de pureza, utilizando-se o método de reação via úmida. Após estudos da ordem de adição e concentração dos reagentes foi possível definir os melhores parâmetros de síntese. Com isso verificou-se a influência do tempo de moagem nas propriedades dos cimentos, sendo constatado que para o fosfato de cálcio preparado pela metodologia proposta, não há necessidade de moagem adicional. Foram testadas formulações de hidrogéis utilizando N-vinil-2-pirrolidona e ou ácido acrílico, utilizando três iniciadores: azobisisobutironitrila, persulfato de amônio e 1- hidroxiciclohexil fenil cetona. Pela adição de formulações de hidrogéis ao cimento foi possível obter compósitos com maior absorção de água, mantendo as propriedades mecânicas, o que pode permitir uma melhor adesão celular ao implante sem comprometer sua estrutura. O ensaio de citotoxicidade in vitro demonstrou que o cimento sintetizado neste trabalho não apresentou efeito tóxico para as células. Mostrando, ainda, a adesão e proliferação de célulastronco mesenquimais e de uma linhagem de osteoblastos.In the last years, intensive studies have been conducted regarding the biocompatible and resorbable bone substitutes, notably calcium phosphate bone cements, for reconstructive surgery and tissue engineering. However, the calcium phosphate cements developed exhibit low mechanical strength when compared with the bones of the human body. In this context, the search for alternatives to minimize this problem has intensified. The obtaining of alphatricalcium phosphate by others synthesis routes, as well as development of calcium phosphate and hydrogels composites has been prominent in this branch. The preparation of these composites allows to combine excellent properties such as: i) osteoconductivity and ability to form bonds with bone tissue, afforded by calcium phosphate and ii) ease of adhesion and distribution of cells in the scaffolds inside, provided by hydrogel. The aim of this work was the development of a new methodology to obtaining alpha-tricalcium phosphate, the preparation of calcium phosphate cements and hydrogels compositions, as well as the obtaining and characterization of composites of these, intended to improve the properties for application as biomaterial. It was possible to synthesize alpha-tricalcium phosphate with high purity using the wet method reaction After studies of the addition order and reagents concentration was possible to define the best synthesis parameters. With that it was verified the influence of milling time on the cements properties to being noted that for the calcium phosphate prepared by the proposed method, there is no need additional milling. Were tested hydrogel formulations using N-vinyl-2-pyrrolidone and/or acrylic acid, using three initiators: azobisisobutyronitrile, ammonium persulfate and 1-hydroxycyclohexyl phenyl ketone. By the addition of the hydrogel formulations to the cement was possible to obtain composites with higher water absorption by keeping the mechanical properties, which may permits better vascularization of the implant without compromising its structure. The in vitro cytotoxicity assay demonstrated that the cement synthesized in this work does not show any toxic effect on the cells. Also, showing the adhesion and proliferation of mesenchymal stem cells and an osteoblast line.
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Rayeroux, David. "Polymérisation radicalaire contrôlée par transfert d'iode en mode inverse (RITP) : Synthèse de copolymères amphiphiles." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2012. http://www.theses.fr/2012ENCM0025/document.
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Ce travail de thèse décrit la synthèse de copolymères diblocs amphiphiles par polymérisation radicalaire contrôlée par transfert d'iode en mode inverse (RITP). Dans un premier temps, des homopolymères à base de monomères activés (styrène, acrylate de méthyle, méthacrylate de méthyle), non activés (acétate de vinyle) et fonctionnels (chlorométhylstyrène, acrylate de tert-butyle), ont été synthétisés par RITP. Des aspects tels que le contrôle des masses molaires ainsi que la fonctionnalité en iode du bout de chaîne ont été examinés. Afin de démontrer la compatibilité de la RITP avec d'autres techniques de polymérisation contrôlée/vivante (non radicalaires), le copolymère amphiphile non-ionique poly(styrène)-b-poly(2-méthyl-2-oxazoline) (PS-b-P(MOx)) a été élaboré par la voie toute iode en procédé « one-pot » en combinant de manière consécutive la RITP du styrène avec la polymérisation cationique par ouverture de cycle (CROP) de la 2-méthyl-2-oxazoline. Par ailleurs, des copolymères cationiques poly(styrène)-b-poly(chlorométhylstyrène) quaternisé avec la triéthylamine (PS-b-PCMS+) et anioniques poly(styrène)-b-poly(acide acrylique) (PS-b-PAA-) ont été synthétisés par RITP du styrène suivie de l'ITP du bloc hydrophile. Tous ces copolymères amphiphiles ont été obtenus à partir de polystyrène iodé (PS-I) de faibles masses molaires, allant de 1000 à 3000 g.mol-1, jouant le rôle de macro-amorceurs (CROP) ou de macro-agents de transfert (ITP). L'étude de l'auto-organisation en phase aqueuse de ces copolymères amphiphiles a révélé la formation de micelles pour des concentrations supérieures à la concentration d'agrégation critique (CAC) dont la valeur a été déterminée par diffusion dynamique de la lumière (DDL) et spectroscopie de fluorescence. Enfin, des résultats très prometteurs ont été obtenus dans l'utilisation d'un copolymère cationique amphiphile PS-b-PCMS+ comme agents structurants de matériaux siliciques mésoporeux nanostructurés élaborés par procédé sol-gel en milieu basique. La synthèse de ces copolymères amphiphiles ainsi que leur caractérisation physico-chimique ont mis en exergue que la RITP permet de couvrir la synthèse de différentes catégories de copolymères amphiphiles, tout en étant une technique simple à mettre en œuvre, peu couteuse et robusteThis manuscript describes the synthesis of amphiphilic diblock copolymers by reverse iodine transfer polymerization (RITP). Firstly, homopolymers derived from activated (styrene, methyl acrylate, methyl methacrylate), non-activated (vinyl acetate) and functional monomers (chloromethylstyrene, tert-butyl acrylate) synthesized by RITP, were studied. Aspects including molecular weight control as well as iodine chain-end functionality were investigated. In order to highlight the compatibility of RITP with other living/controlled (non-radical) polymerization techniques, a poly(styrene)-b-poly(2-methyl-2-oxazoline) (PS-b-P(MOx)) non-ionic copolymer was conceived through an ‘all-iodine', ‘one-pot' process by combining successively RITP of styrene with cationic ring-opening polymerization (CROP) of 2-methyl-2-oxazoline. Besides, poly(styrene)-b-poly(chloromethylstyrene) quaternized with triethylamine (PS-b-PCMS+) cationic copolymers and poly(styrene)-b-poly(acrylic acid) (PS-b-PAA-) anionic copolymers were elaborated by RITP of styrene, followed by ITP of the hydrophilic moiety. All these amphiphilic copolymers were obtained from iodine-bearing chain-end poly(styrene) (PS-I) of low molecular weights, in the range of values of 1000 to 3000 g.mol-1, playing the role of macro-initiators (CROP) or macro-transfer agents (ITP). Studies of the self-assembly of these amphiphilic copolymers in aqueous phases revealed the formation of micelles for concentrations superior to the critical aggregation concentration (CAC). The latter value was determined by dynamic light scattering (DLS) and fluorescence spectroscopy. Moreover, highly-promising results were obtained in the use of PS-b-PCMS+ cationic copolymers as structuring agents meant for the elaboration of nanostructured, mesoporous silica-based materials through the sol-gel process in basic medium. Both the synthesis of the amphiphilic copolymers and their physico-chemical characterizations have evidenced that RITP fosters the synthesis of different categories of amphiphilic copolymers, while being a simple, cheap and robust technique
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Arias, Liliana Patricia Olivo. "Modeling and experimental study of inverse suspension polymerization of acrylic acid and trimethylolpropane triacrylate for hydrogel production." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-22082016-113710/.
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In the present work, a super water-absorbent poly(acrylic acid) was synthetized by inverse suspension polymerization, using Span60 as the dispersant, toluene as the dispersing organic phase, trimethylolpropane triacrylate as the crosslinking agent, and sodium persulfate as the initiator. The synthesis was conducted in a small-scale glass reactor operated in semi-batch mode. The following reaction conditions were evaluated: effects of initiator concentration, temperature, percentage of multifunctional cross-linker agent and monomer concentration. Also, two important properties were determined, conversion and gel fraction. A kinetic model including a population balance was employed to simulate the process. The proposed model uses the numerical fractionation technique and is capable of predicting the pre-gel and post-gel properties, the effect of the crosslinking agent level on the polymer properties and the dynamic of gelation. The model was compared with the experimental results and showed a satisfactory representation of the system after parameter adjusting.No presente trabalho, o poli (ácido acrílico) super-absorvente foi sintetizado por polimerização em suspensão inversa, usando Span 60 como o dispersante, tolueno como fase orgânica, trimetilolpropano triacrilato como agente de reticulação e persulfato de sódio como iniciador. A síntese foi conduzida num reator de vidro em escala de bancada, operado em modo semi-batelada-batelada. As seguintes condições da reação foram avaliadas: os efeitos da concentração de iniciador, a temperatura, a porcentagem de agente de reticulação multifuncional e a concentração de monómero. Além disso, foram determinadas propriedades importantes, como a conversão e a fração de gel. Da mesma forma, foi desenvolvido um modelo de balanço populacional para simular o processo em conjunto com a técnica de fracionamento numérico, que é capaz de prever as propriedades pré-gel e pós-gel, o efeito do nível do agente de reticulação no polímero e as propriedades da dinâmica de gelificação. O modelo foi comparado com os resultados experimentais e mostrou uma representação satisfatória do sistema após o ajuste dos parâmetros.
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Moussa, Mariam. "Loading of dendrimer nanoparticles into layer-by-layer assembled Poly(diallyl dimethyl ammonium) chloride-(Poly(acrylic acid))n Multilayer Films : Particle Electrokinetics, Film Structure Dynamics and Elasticity." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0383/document.
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Une analyse détaillée des propriétés physico-chimiques des nanoparticules (NP) anthropogéniques est nécessaire pour comprendre à un niveau mécanistique leurs interactions/toxicité potentielle avec/envers les composants biotiques des systèmes aquatiques naturels. Une telle analyse est également requise pour réaliser une évaluation complète et une optimisation de la performance des méthodes d’(ultra)filtration développées pour circonscrire le relargage des NPs dans les milieux aquatiques. Dans ce contexte, l'objectif de cette thèse de doctorat était de déchiffrer les processus physico-chimiques fondamentaux régissant la capture de nanodendrimères carboxylés (PAMAM-COOH) - utilisés fréquemment dans des applications biomédicales – par des films multicouches du type (poly(diallyldiméthylammonium)chlorure-poly(acide acrylique))n ((PDADMAC-PAA)n) assemblés par déposition séquentielle des composantes polymériques cationique et anionique. À cette fin, une étude systématique des propriétés électrohydrodynamiques des NPs PAMAM-COOH a d'abord été effectuée en fonction du pH et de la concentration en sel monovalent du milieu. Sur la base de la théorie électrocinétique de particules molles ayant une fonctionnalité zwitterionique, il est démontré que les caractéristiques électriques interfaciales des NPs considérées sont déterminées à la fois par des contributions électrostatiques de surface et volumique des nanoparticules, lesquelles dependent de l’extension intraparticulaire de la double couche électrique. L’existence de ces deux types de contributions conduit à un changement remarquable de signe de la mobilité des NPs en modifiant la concentration du sel monovalent en solution et à une dépendance prononcé du point de zéro mobilité des NPs avec la concentration de l’électrolyte. En outre, une confrontation quantitative entre résultats expérimentaux et théorie souligne comment les modifications structurales des NPs induites par des changements de pH et de salinité affectent les caractéristiques électrocinétiques des dendrimères. Dans une deuxième partie, la structure, la morphologie et les propriétés mécaniques des films PDADMAC-PAA et leur évolution temporelle dans des conditions de vieillissement naturel ou après traitement thermique ont été déterminées par microscopie à force atomique (AFM) et analyses microspectroscopie Raman. Les résultats démontrent que les films multicouches PDADMAC-PAA de type exponentiel présentent des caractéristiques mécaniques et structurelles typiques de films polyélectrolytes multicouches à croissance linéaire. En particulier, leur relaxation lente vers un état d’équilibre est accélérée après traitement thermique à 60°C et se révèle être intimement liée à l'instabilité de domaines de films riches en PDADMAC, épuisés en eau (faits confirmés par la théorie de la fonctionnelle de la densité) et marqués par la présence de structures caractéristiques en forme de ‘donuts’. Dans une dernière partie, des résultats préliminaires sont donnés pour la dépendance de l'élasticité des films multicouches PDADMAC-PAA avec la concentration en solution de nanodendrimères. Les résultats suggèrent que ces films multicouches complexes constituent une option prometteuse pour la capture et l'élimination de nanodendrimères carboxylés présents en milieux aqueuxA detailed analysis of the physicochemical properties of engineered nanoparticles (NPs) is required to understand on a mechanistic level their interactions/potential toxicity with/towards biotic components of fresh water systems. Such an analysis is further mandatory to achieve a comprehensive evaluation and optimisation of the performance of (ultra)filtration methods developed to prevent NPs release into aquatic media. Within this context, the aim of this PhD thesis was to decipher the basic physico-chemical processes governing the loading of carboxylated-poly(amidoamine) (PAMAM-COOH) nanodendrimers -commonly employed in biomedical applications- into layer-by-layer assembled (poly(diallyl dimethyl ammonium) chloride-poly(acrylic acid))n ((PDADMAC-PAA)n) multilayer films. For that purpose, a systematic investigation of the electrohydrodynamic properties of PAMAM-COOH NPs was first performed as a function of pH and monovalent salt concentration in solution. On the basis of advanced electrokinetic theory for soft particles with zwitterionic functionality, it is demonstrated that the interfacial electrostatic features of the considered NPs are determined both by surface and bulk particle contributions to an extent that depends on electrolyte concentration. This leads to a remarkable NPs mobility reversal with changing monovalent salt concentration and to a marked dependence of the point of zero NPs mobility on electrolyte content. In addition, confrontation between experiments and theory further highlights how pH- and salt-mediated modifications of the NP particle structure affect dendrimer electrokinetic features at large pH and/or low salt concentrations. In a second part, the structure, morphology and mechanical properties of PDADMAC-PAA films, and their evolution over time under natural aging conditions or after thermal treatment, were addressed from atomic force microscopy (AFM) and Raman microspectroscopy analyses. Results evidence that PDADMAC-PAA multilayer films of exponential type exhibit mechanical and structural features that are typical for polyelectrolyte multilayer films with linear growth. In particular, their slow relaxation to equilibrium is accelerated after heating treatment at 60°C and, in line with density functional theory computation, this relaxation dynamics is shown to be intimately connected to instability of film domains rich in PDADMAC, depleted in water and marked by the presence of characteristic donut-like structures. In a final part, the reported dependence of PDADMAC-PAA multilayer films elasticity on concentration of nanodendrimers in bulk solution suggests that these complex multilayer films constitute a promising option to be further investigated for the loading and removal of carboxylated nanodendrimers from aqueous environments
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Chaduc, Isabelle. "Synthèse d'agents RAFT macromoléculaires hydrophiles à base d'acide (méth)acrylique ou d'alginate pour l'élaboration de nanoparticules par polymérisation en émulsion." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10193/document.
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Ces travaux décrivent la synthèse de nanoparticules stabilisées par des polyélectrolytes d’originesynthétique (poly(acide (méth)acrylique)) ou naturelle (alginate) par polymérisation radicalairecontrôlée (PRC) de type RAFT en émulsion. Ce procédé est basé sur l’utilisation d’un polymèrehydrophile obtenu par RAFT (macroRAFT) qui est réactivé dans l’eau pour la polymérisation d’unmonomère hydrophobe. Des copolymères à blocs amphiphiles sont ainsi générés et s’auto-assemblent in situ pour former des nanoparticules. Dans un premier temps, nous avons cherché à conduire l’ensemble du procédé en milieu aqueux. Des études ont ainsi été menées sur la polymérisation RAFTdans l’eau de l’acide acrylique et de l’acide méthacrylique. Des homopolymères bien définis ont été obtenus sur une large gamme de conditions, puis ont été utilisés comme macroRAFTs pour la polymérisation en émulsion de monomères hydrophobes. Des nanoparticules stables constituées de copolymères à blocs amphiphiles bien définis ont été produites. Il a été montré que le contrôle de la polymérisation et la nucléation dépendaient fortement du pH, mais qu’une bonne stabilité colloïdale était néanmoins observée dans tous les cas. Ce procédé "one-pot " a ensuite été extrapolé à la synthèse de particules stabilisées par des copolymères hydrophiles de N-acryloylmorpholine (NAM) et de macromonomères d’alginate. Des nano-objets aux morphologies variées ont été obtenus. Afin de mieux appréhender la formation de ces morphologies, un système modèle employant un copolymère hydrophile de NAM et de macromonomère de polyNAM obtenu par polymérisation RAFT a été étudiépour la polymérisation en émulsion du styrèneThis work describes the synthesis of nanoparticles stabilized by polyelectrolytes from synthetic(poly((meth)acrylic acid)) or natural (alginate) source by controlled free radical polymerization (CRP),namely RAFT, in emulsion. This process is based on the use of a hydrophilic polymer prepared by RAFT (i.e. macroRAFT) which is reactivated in water for the polymerization of a hydrophobic monomer. The formation of amphiphilic block copolymers which self-assemble in situ leads to the formation of nanoparticles. Firstly, we tried to perform the whole process in water. The RAFT polymerization of acrylic acid and methacrylic acid was studied in this context. Well-defined homopolymers were obtained under a large range of conditions, and further used as macroRAFTs in emulsion polymerization of hydrophobic monomers. Stable nanoparticles composed of well-defined amphiphilic block copolymers were produced. It was shown that the control of the polymerization and the nucleation were strongly dependent on the pH. Nevertheless, a good colloidal stability wasobserved in all cases. This “one-pot” process was then extrapolated to the synthesis of particles stabilized by hydrophilic copolymers of N-acryloylmorpholine (NAM) and alginate macromonomer. Nano-objects with various morphologies were obtained. In order to better understand the formation of these morphologies, a model system using a hydrophilic copolymer of NAM and a polyNAM macromonomer obtained by RAFT polymerization was studied in styrene emulsion polymerization
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Chen-Jolly, Hongyu. "Conception d'un dispositif microfluidique de synthèse en continu du poly(acide acrylique) en milieu hétérogène eau/CO2 supercritique." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0233/document.
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Ce travail de thèse rend compte de la mise en oeuvre d’un système de synthèse en continu dupoly(acide acrylique) en milieu CO2 supercritique (15 MPa et 75 °C). Nous avons conçu undispositif microfluidique résistant aux hautes pressions permettant l’écoulement de gouttes desolution aqueuse de monomère dans une phase continue constituée d’un mélangesupercritique d’éthanol dans du CO2 et contenant l’amorceur azobisisobutyronitrile (AIBN).Nous avons déterminé par spectroscopie IR la répartition des différentes espèces chimiquesdu mélange en fonction de la pression et la température, puis caractérisé la décompositionthermique de l’amorceur selon la composition du milieu réactionnel par spectroscopie UVVis.Enfin, nous avons montré que les gouttes sont comparables à des réservoirs demonomère alimentant sans cesse la phase continue. En raison de ce transfert rapide vis-à-visde la conversion de l’AA en chaîne polymère, la réaction de polymérisation s’effectuecontinûment avec un rapport molaire monomère sur amorceur constant durant tout le tempsde séjour dans le microcanal (jusqu’à 41 min). Une gamme large de masses molaires avec desindices de polymolécularité faibles a été obtenue : de 20 000 à 120 000 g.mol-1 pour 1,35 à1,70, en variant simplement les concentrations de monomère de la solution aqueuse initiale.Les paramètres expérimentaux influençant les propriétés du poly(acide acrylique) obtenu,ainsi que le lieu de la polymérisation ont été étudiésIn this work, a continuous microfluidic device was developed to perform the synthesis ofpoly(acrylic acid) in supercritical CO2 (15 MPa and 75°C). This high pressure resistantdevice allows generating segmented flows in microcanal: an aqueous solution of monomerwas dispersed in a mixture of ethanol in CO2 containing initiator AIBN. The distribution ofdifferent components in this biphasic system has been determined by IR spectroscopyaccording to the pressure and the temperature. The thermal decomposition of AIBN indifferent reaction media has been investigated using UV-Vis spectroscopy. During thereaction, the droplets were used as reservoirs which insure the transfer of monomer to thecontinuous phase. Because of this rapid transfer compared to the reaction conversion, thepolymerization reaction was carried out continuously with a constant molar ratio betweenmonomer and initiator throughout the residence time (up to 41 min). It has been showed thata large range of molecular weights of poly(acrylic acid) (20 000 and 120 000 g.mol-1) withlow polydispersity index (1.35 à 1.70) can be obtained by just changing the initial monomerconcentration in the droplets. The effect of other parameters influencing the properties ofpoly(acrylic acid) as well as the locus of polymerization have been discussed
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Thickett, Stuart Craig Vincent. "The Kinetics of Electrosterically Stabilized Emulsion Polymerization Systems." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/2380.
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The kinetics of electrosterically stabilized emulsion systems was studied. The aim of this was to understand the impact that steric and electrosteric stabilizers have on the kinetics of particle growth and particle formation in the area of emulsion polymerization. The well-established mechanisms that govern these processes for emulsions stabilized by conventional low molecular weight surfactants were used as a reference point for comparative purposes. Model latexes were synthesized that comprised of a poly(styrene) core stabilized by a corona of poly(acrylic acid). The advent of successful controlled radical polymerization techniques in heterogeneous media (via RAFT polymerization) allowed for latexes to be synthesized under molecular weight control. For the first time, the degree of polymerization of the stabilizing block on the particle surface was able to be controlled and verified experimentally using mass spectrometry techniques. Three latexes were made with different average degrees of polymerization of the stabilizing block; five, ten and twenty monomer units respectively. A methodology was developed to remove the RAFT functionality from the polymer chains present in the emulsion while retaining the desired particle morphology. Oxidation with tertbutylhydroperoxide (TBHP) was proven to be successful at eliminating the living character provided by the thiocarbonyl end-group. Extensive dialysis and cleaning of the latex was performed to ensure no residual TBHP or reaction by-products remained. Latexes with poly(styrene) cores were chosen for this work as poly(n-butyl acrylate) latexes were shown to be influenced by chain transfer to polymer, providing an additional kinetic complication. The three electrosterically stabilized emulsions were used as seed latexes in carefully designed kinetic experiments to measure the rate of polymerization as a function of time. Two independent techniques (chemically initiated dilatometry and γ-relaxation dilatometry) were used to measure the rate coefficients of radical entry (ρ) and exit (k) in these systems – the two parameters that essentially govern the rate of particle growth. The latexes were chosen such that they satisfied ‘zero-one’ conditions (i.e. that any given latex particle contains at most one growing radical at any given time) in order to simplify data analysis. Three different chemical initiators were used, each yielding a radical with a different electric charge. Results from γ-relaxation experiments demonstrated that the three electrosterically stabilized latexes gave very long relaxation times when removed from the radiation source, ultimately yielding very small k values. These values were up to a factor of 10 smaller than that predicted by the ‘transfer-diffusion’ model for exit for particles of that size. This reduction was attributed to a ‘restricted diffusion’ effect, where the exiting monomeric radical has to diffuse through a dense layer of polymer on the particle surface, where its mobility will be restricted. Modification of the Smoluchowski equation for diffusion-controlled adsorption/desorption to account for this postulate led to the development of a model that gave excellent semi-quantitative agreement with experiment. Chemically initiated dilatometric experiments (using three different types of initiator) gave the unusual result of very low reaction rates and low steady-state values of 'nbar', the average number of radicals per particle. Using the standard kinetic equations for styrene-based systems (where it is assumed that an exited monomeric radical undergoes re-entry), this led to the calculation of impossibly small values of the entry rate coefficient ρ (far below any background or ‘thermal’polymerization rate). However upon removing the assumption of re-entry and assuming that exited radicals undergo termination, the obtained values of ρ were in almost perfect agreement with the values predicted from the ‘control by aqueous phase growth’ entry mechanism. This unexpected result was attributed to chemical reaction with the poly(acrylic acid) stabilizers through chain transfer to polymer (via hydrogen-atom abstraction). This postulate was verified by separate experiments that demonstrated that poly(acrylic acid) could act as a reasonably efficient chain transfer agent for styrene polymerization. The addition of poly(acrylic acid) to the aqueous phase of a conventionally stabilized emulsion also led to the rate reduction seen previously. NMR experiments demonstrated the existence of poly(acrylic acid-graft-styrene), which could only be formed through termination of a poly(styrene) chain with a poly(acrylic acid) chain bearing a mid-chain radical (as the product of a chain transfer reaction). These additional terms of transfer and termination were included in the governing kinetic equations of emulsion systems (the Smith-Ewart equations) to develop a model to account for the behaviour of electrosterically stabilized latexes. The ultimate fate of an exiting radical was now shown to be a competition between fates; successful desorption into the aqueous phase, or chemical reaction (through transfer or termination) within the hairy layer. These additional terms were shown to significantly reduce the theoretical value of nbar, and were in excellent agreement with experiment. For small electrosterically stabilized particles with a densely packed ‘hairy layer,’ it was seen that transfer/termination is the dominant loss mechanism as opposed to desorption. The developed model showed that as the particle size was increased, the dominant loss mechanism once again became successful desorption into the aqueous phase. The model was shown to give excellent agreement with experimental data from ‘uncontrolled’ emulsion systems. To explain the highly unusual secondary nucleation behaviour seen in systems such as these, it was postulated that beta-scission of a poly(acrylic acid) chain bearing a mid-chain radical is an important mechanistic step in the nucleation mechanisms of these systems. Modelling (both steady-state and time-dependent) gave good agreement with experiment with a minimal number of adjustable parameters. Theory (and supporting experimental evidence) demonstrated that this nucleation mechanism is only significant at high particle numbers; under other conditions the well-known ‘homogeneous nucleation’ mechanism is once again dominant.
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Dunn, Andrew W. "Hyperthermic ablation of MDA-MB-231 human mammary gland adenocarcinoma mediated by the photothermal effect of poly(acrylic acid) coated magnetite nanoparticles, efficacy and applicability for novel cancer treatment." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384849962.
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Särnholm, Evelina. "Analyzing components of barrier coatings in different fractions during a repulping process." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-93414.
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During paper manufacturing, coating and adhesives are added to paper and cardboard to improve quality and durability. When the paper is later recycled or becoming new paper, the coatings may pollute the water used in the recycling process. Thus, it is important to know in which fraction these coatings finish during the process. In this study, laboratory made samples that mimic the repulping and paper making process is used. The different fractions of the processes were analyzed for a clay as well as a polymer coating. Metal content from clay coating is analyzed using inductively coupled plasma-mass spectrometry and microwave plasma-atomic emission spectrometry. For analyzing polymer coating, gas chromatography-mass spectrometry was used. From the result of the analysis the Reject sample, which was collected with a bigger mesh sieve in a repulping system, contained the highest amount of both clay and polymer coating. The other sample fractions from the repulping process and paper making process, did not contain as high mass content of either clay nor polymer coating.
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Authimoolam, Sundar Prasanth. "STABILITY OF AFFINITY BASED LAYER-BY-LAYER POLYMERIC SELF-ASSEMBLIES FOR ORAL WOUND APPLICATIONS." UKnowledge, 2011. http://uknowledge.uky.edu/cme_etds/3.
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Oral mucositis is a painful and debilitating chronic inflammatory condition that can result from chemo and/or radiotherapy. While current treatment strategies which provide temporary relief exist, there is still an unmet clinical need for a robust long active barrier strategy which can simultaneously provide protection and release drug to enhance the wound healing response. It is proposed that an affinity based layer-by-layer self-assembled barrier administered as a series of mouth rinses can allow for wound specific drug delivery, providing an effective regenerative therapy.
In this work, biotinylated poly(acrylic acid) is used to develop LBL assemblies based upon biotin-streptavidin affinity interactions. To explore the ability of developed LBL assemblies to resist the harsh intraoral environment, in vitro chemical and ex vivo mechanical tests are performed. The stability results demonstrate significant LBL barrier stability with wear resistance. From principal component regression analysis, factors such as polymer MW and number of layers in assemblies contributed significantly to chemical barrier stability. Also it is observed that the extent of biotin conjugation plays a significant role in LBL development and in mechanical stability. Thus, the proposed affinity based multilayered assemblies with their excellent barrier properties offer a modular treatment approach in oral mucosal injuries.
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Nugroho, Robertus Wahyu Nayan. "Steric Stabilization of Polylactide particles achieved by Covalent 'grafting-from' with Hydrophilic Polymers." Licentiate thesis, KTH, Polymerteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122429.
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Despite numerous advantages of using particles in a wide range of applications, they have one drawback that is their tendency to agglomerate. One way to overcome this problem is to sterically stabilize the particles by introducing polymeric chains covalently attached to the surface. Surface modification by covalently attaching polymer chains to the particle surface can be achieved by e.g. a ‘grafting-from’ technique under UV irradiation. In this thesis, polylactide (PLA) particles were surface modified, under UV irradiation, with the hydrophilic monomers: acrylamide (AAm), acrylic acid (AA), and maleic anhydride (MAH). The developed ‘grafting-from’ technique was shown to be nondestructive method for surface modification of PLA particles of two different geometries. The change in surface chemistry of the PLA particles was confirmed by FTIR and XPS, indicating the success of the surface grafting technique. Force interaction between two surface grafted PLA substrates was measured by colloidal probe AFM in different salt concentrations. In order to understand the repulsive force, the AFM force profiles were compared to the DLVO theory and AdG model. Long range repulsive interactions were mainly observed when hydrophilic polymers were covalently attached to the surface of PLA particles, leading to steric interaction. Attractive force dominated the interaction when neat PLA particle was approaching each other, resulting in particle aggregation, even though short range repulsion was observed at small separation distance, i.e. approximately 10 nm. Attractive interaction was also observed when neat PLA was approaching to PAA-grafted PLA substrate. This attractive interaction was much greater than force interaction between two neat PLA substrates. The surface grafted particles can be used in biomedical application where secondary interactions are important to overcome particle agglomeration such as particle-based drug delivery.QC 20130529
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ARAÚJO, Jeane Paulino de. "Avaliação da reatividade entre o Biopolímero poli (Ácido Lático) (PLA) e o polietileno enxertado com ácido acrílico (PEgAA) e do efeito da concentração de PEgAA nas propriedades e na morfologia da blenda PLA/PEgAA." Universidade Federal de Campina Grande, 2018. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1059.
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Capes
O poli(ácido lático) (PLA) tem despertado grande interesse tanto da academia como da indústria devido principalmente a sua biodegradabilidade, algumas propriedades mecânicas atraentes e por ser sintetizado a partir de matéria-prima de fontes renováveis. Entretanto, o PLA apresenta algumas desvantagens, como alta fragilidade, baixa taxa de cristalização, sensibilidade a umidade e a degradação em altas temperaturas, que limitam suas aplicações e comprometem seu processamento e desempenho final, sendo necessário muitas vezes modificar o PLA para que este possa atender as expectativas de mercado. Desse modo, foi realizada a modificação do PLA através de blendas com o polietileno enxertado com ácido acrílico (PEgAA), sendo avaliada a reatividade entre os grupos funcionais dos dois polímeros e o efeito de diferentes concentrações do copolímero PEgAA nas propriedades das blendas. As blendas PLA/PEgAA contendo 5, 10, 15 e 20% (em massa) do PEgAA foram preparados em uma extrusora dupla-rosca corrotacional, sendo caracterizadas por espectroscopia na região do infravermelho com transformada de Fourier (FTIR), calorimetria exploratória diferencial (DSC), análise térmica dinâmico-mecânica (DMTA), propriedades mecânicas, microscopia eletrônica de varredura (MEV), difratometria de raios X (DRX) e ensaios reológicos. A análise por FTIR indicou a ocorrência de uma reação de poliesterificação entre os grupos hidroxila do PLA e os grupos carboxila do PEgAA. As análises DSC e DMTA indicaram que a adição do PEgAA levou à diminuição tanto da temperatura de transição vítrea (Tg) como da temperatura de cristalização a frio (Tcc) do PLA nas blendas. Com o aumento do teor de PEgAA nas blendas houve aumento do tamanho dos domínios de PEgAA. Com a incorporação do PEgAA houve ligeiro aumento da resistência ao impacto para as blendas com 5 e 10% do PEgAA em relação ao PLA puro. A blenda PLA/PEgAA contendo 15% do PEgAA apresentou maior viscosidade complexa e o módulo de armazenamento a baixas frequências.
The poly(lactic acid) (PLA) has attracted great interest from both academia and industry mainly due to its biodegradability, some attractive mechanical properties and because it is synthesized from raw materials from renewable sources. However, PLA has some drawbacks such as high brittleness, low crystallization rate, sensitivity to moisture, and deterioration at high temperatures, which limit its applications and compromise its processing and final performance, needing to be modified, so it can meet market expectations. Thus, the modification of PLA was carried by blending it with polyethylene grafted with acrylic acid (PEgAA), assessing the reactivity between the functional groups of the two polymers and the effect of different PEgAA copolymer content on the properties of PLA/PEgAA blend. PLA/PEgAA blends containing 5, 10, 15 and 20% (wt) of PEgAA were prepared in a co-rotational twinscrew extruder, and characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), mechanical properties, scanning electron microscopy (SEM), X-ray diffraction (XRD) and rheological measurements. FTIR results indicated that a polyesterification reaction between the hydroxyl groups of PLA and the carboxyl groups of PEgAA has occurred. DSC and DMTA analyses indicated that the addition of PEgAA to PLA led to the decrease in both the glass transition (Tg) and the cold crystallization (Tcc) temperatures. The PEgAA domains size increased with the increase in the PEgAA content. With the addition of PEgAA there was a slight increase in the impact strength of the blends containing 5 and 10% of PEgAA, when compared to that of neat PLA. The PLA/PEgAA blend containing 15% (wt) of PEgAA presented the highest complex viscosity and storage modulus at low frequencies.
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Lima, Maria do Socorro Pereira de. "Preparo e caracteriza??o de membranas de quitosana modificadas com poli (?cido acr?lico)." Universidade Federal do Rio Grande do Norte, 2006. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17776.
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Previous issue date: 2006-11-17The aim of this study was to generate an asymmetric biocompactible and biodegradable chitosan membrane modified by the contact with a poly(acrylic acid) solution at one of its sides at room temperature and 60◦C. The pure chitosan membrane, as well as the ones treated with poly(acrylic acid) were characterized by infrared spectroscopy (FTIRATR) at angles of 39◦, 45◦ and 60◦ , swelling capacity in water, thermal analysis (TG/DTG), scanning electronic microscopy (SEM) and permeation experiments using metronidazole at 0,1% and 0,2% as a model drug. The results confirmed the presence of ionic interaction between chitosan and poly(acrylic acid) by means of a polyelectrolyte complex (PEC) formation. They also showed that such interactions were more effective at 60◦C since this temperature is above the chitosan glass transition temperature wich makes the diffusion of poly(acrylic acid) easier, and that the two treated membranes were asymmetrics, more thermically stable and less permeable in relation to metronidazole than the pure chitosan membrane
O prop?sito deste estudo foi produzir uma membrana assim?trica biocompat?vel e biodegrad?vel de quitosana modificada pelo contato com uma solu??o de poli(?cido acr?lico) em uma de suas superf?cies ? temperatura ambiente e a 60◦C. As membranas de quitosana pura, quitosana com poli(?cido acr?lico) a 25◦C e quitosana com poli(?cido acr?lico) a 60◦C foram caracterizadas por: espectroscopia no infravermelho (FTIRATR) em ?ngulos de incid?ncia de 39◦, 45◦ e 60◦, ganho de massa em ?gua, an?lise t?rmica (TG/ DTG), microscopia eletr?nica de varredura (MEV) e, ainda, atrav?s dos ensaios de permea??o in vitro utilizando como f?rmaco modelo o metronidazol em solu??o aquosa nas concentra??es de 0,1 e 0,2%. Os resultados obtidos comprovaram a exist?ncia de intera??es i?nicas entre os dois pol?meros, atrav?s da forma??o dos chamados complexos polieletrol?ticos. Tamb?m mostraram que a reticula??o foi mais efetiva a 60◦C , uma vez que essa temperatura est? acima da temperatura de transi??o v?trea da quitosana, o que facilita a difus?o do poli(?cido acr?lico) e que as membranas resultantes s?o assim?tricas, mais est?veis termicamente e menos perme?veis ao metronidazol do que a membrana de quitosana pura
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Meng, Linghui. "Polymer Biomaterial Constructs For Regenerative Medicine and Functional Biological Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1327682278.
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Swift, Thomas, Colin C. Seaton, and Stephen Rimmer. "Poly(acrylic acid) interpolymer complexes." 2017. http://hdl.handle.net/10454/14145.
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YesInterpolymer complex formation of poly(acrylic acid) with other macromolecules can occur via several mechanisms that vary depending on the pH. At low pH the protonated acid functional group can form bonds with both donor and acceptor moieties, resulting in desolvated structures consisting of two polymers. Complexes were formed in dilute solutions of PAA, functionalised with acenaphthylene, with a range of other polymers including: poly(NIPAM); poly(ethylene oxide) (PEO); poly(dimethylacrylamide) (PDMA); poly(diethyl acrylamide) (PDEAM) poly(vinyl alcohol) (PVA) and poly(vinyl pyrolidinone) (PVP). Fluorescence anisotropy was used to demonstrate complex formation in each case by monitoring the reductions in segmental motion of the chain as the complexes formed. Considerations of the molecular structures of the complexing moieties suggest that solvation energies and pKas play an important role in complex formation.
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Yu, Shi Ping, and 游士平. "Chitosan-Poly(acrylic acid) Nanoparticles for Ophthalmic Drug Delivery." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/48493651512222925183.
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碩士南台科技大學
化學工程系
93
In this study, Chitosan-Poly (acrylic acid) (CS-PAA) complex nanoparticles were prepared by template polymerization of acrylic acid (PAA) in the chitosan solution. The preparation and characterization of CS-PAA nanoparticles including the yields of the nanoparticles, FT-IR spectrum analysis, dynamic light scattering, zeta potential, and morphology of nanoparticles were concentrated in this study. The effects of temperature, weight ratio of CS and PAA, and pH value on the physicochemical properties of nanoparticles were studied. It was found that the surface structure and zeta potential of nanoparticles can be controlled by different preparation processes, and the morphology was influenced by the pH value of the medium. Results of our experiments showed that the diameter distribution of the CS-PAA nanoparticles was smallest when the polymerization was carried out at 70℃ for 45 minutes with a CS:AA ratio of 1:1. It was also found that the surface structure of the nanoparticles was most stable in a buffer solution at a pH value of 4.5 because of their smallest mean diameter (92.0±5.5 nm) and stable zeta potential (25.5±2.6 mV). The experiment of in vitro and in vivo drug release showed that these nanoparticles provided a sustained release of the entrapped drugs, which was better than that of commercial eye drops, and the release behavior was influenced by the pH value of the medium. Chitosan precipitates at high pH environment due to its own characteristics. Nanoparticles prepared in this study was found to precipitate when pH value was greater than 6. To conquer this problem, chitosan was modified in the second part of this thesis. The solubility of chitosan was affected by its degree of deacetylation (DD), viscosity, and molecular weight. The most important factor was the molecular weight. In this experiment, the depolymerization of chitosan by hydrogen peroxide was studied. Results of our experiments showed that the depolymerization rate of chitosan depended on the reaction temperature, the reaction time and the concentration of hydrogen peroxide. The 40k Dalton molecular weight of chitosan was obtained when the depolymerization was carried out at 60℃ for 2 hours using 2M H2O2. The product maintained its good solubility and dispersion in high pH value and is suitable to be used as carrier for ophthalmic drug delivery.
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Swift, Thomas, N. Paul, L. Swanson, Maria G. Katsikogianni, and Stephen Rimmer. "Förster Resonance Energy Transfer across interpolymer complexes of poly(acrylic acid) and poly(acrylamide)." 2017. http://hdl.handle.net/10454/12700.
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YesInterpolymer complexes of homopolymer macromolecules are often described as ‘laddered’ or ‘ribbon’ type structures. The proposition of the existence of these ladder structures seems to us not reasonable and here we examine this hypothesis. To address this we have used polymers enabled for Förster Energy Transfer (FRET). Chromophores bound to a macromolecular backbone can transfer energy across short distances via FRET. The close binding of poly(acrylamide) and poly(acrylic acid) interpolymer complex formation at low pH forms a structure compact enough for significant energy transfer to occur between different chains containing naphthalene and anthracene labels. In the context of the proposition that ladder polymers can form it was surprising that the distance between labels on the same polymer back-bone was equivalent regardless of whether the polymer was complexed or not. The data indicated that the bicomponent structure may be more compact than previously supposed: I.e. the complexes are not ladders composed of extended chains. This evidence suggests formation not of ordered ‘ladder’ systems but colloidal ‘co-globules’.
This work was carried out in part thanks to an EPSRC CASE funded PhD studentship at the University of Sheffield, sponsored by SNF (UK) Ltd.
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Ting-HaoLiu and 劉庭豪. "Poly(Acrylic Acid) Derivatives with Pendent Redox Moieties: Synthesis and Characterization." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/nkbr77.
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碩士國立成功大學
化學工程學系
105
In this study, we successfully synthesize a series of poly(acrylic acid) derivatives with a benzoquinone moieties. We use different molecular weights of poly(acrylic acid) with different ratios of benzoquinone moieties in order to compare the cost and efficiency for the redox flow battery system in the future. The results from cyclic voltammetry showed that these polymers have half oxidation potentials. With higher ratio of benzoquinone, the oxidation peak shows stronger signal. The results also showed the reversible reduction and oxidation peaks, which indicated that these PAA derivatives are redox polymers and a potential material system for redox flow battery. In the future, we need to find another half-cell system to complete the full redox flow battery system.
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Whitty, Elizabeth G. "Assessment of the "smart" polymer poly(acrylic acid) for drug delivery." Thesis, 2015. http://hdl.handle.net/1959.7/uws:36580.
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Anticancer drug delivery systems are currently in the spotlight of anticancer research in order to address the harmful side effects commonly associated with anticancer drug treatment. The unique ability of “smart” polymers to respond to external stimuli, including changes to pH, make them promising candidates for anticancer drug delivery and cell specific targeting. Tumour tissues have a higher acidity than non‐cancerous surrounding tissues. In this study the potential of the pH‐responsive “smart” polymer poly(acrylic acid) (PAA) was investigated. PAA has functional groups that become ionised in response to pH changes, resulting in the chemical nature of PAA becoming altered to form poly(sodium acrylate) (PNaA). Nuclear Magnetic Resonance (NMR) spectroscopy was used to assess the purity of PNaA analogues and the effectiveness of multiple purification processes. 1H NMR spectroscopy detected the presence of residual impurities (1,4‐dioxane and acrylic acid/sodium acrylate monomers) from synthesis in polymers that were purified by the commonly used precipitation. Dialysis was used as the secondary purification method to remove residual impurities; their removal was confirmed by 1H NMR and free solution Capillary Electrophoresis (CE). Free solution CE analysis of the dialysed 3–arm star and hyperbranched PNaA samples determined through significant change in polymer peak intensity that a change in the polymer structure had potentially occurred. Novel UV irradiation studies were also conducted on the 3‐arm star and hyperbranched PNaA architectures to assess if photodegradation had occurred to the polymer during dialysis as it was not conducted in a light controlled environment. Photodegradation studies were inconclusive without a definitive evidence of degradation. Cytotoxicity of dialysed PNaA analogues was assessed via the MTT assay with L6 myoblast cells and L1210 progenitor leukaemia cells used as noncancerous and cancerous models, respectively. While L1210 progenitor cell line studies resulted in an IC50 determination and a dose‐dependent cytotoxicity, the L6 myoblast cell line studies displayed a significant increase in cellular proliferation to levels above that of the controls. This increase when compared to the controls suggests that the MTT assay may not be an appropriate cell based cytotoxicity assay for PNaA. As the MTT is based on mitochondrial activity it is possible that the polymer is affecting cellular mitochondrial production. Preliminary novel studies into the grafting of a fluorescent tag to linear PNaA using a model compound were conducted. CE was used to monitor the grafting efficiency for the first time in this study. Grafting was confirmed by peak area and electrophoretic mobility analysis and the grafting was characterised via novel dispersity studies. Previous results obtained into the interaction of PNaA and serum proteins was reanalysed as previously the absorbance was not corrected when converting migration times to electrophoretic mobility as stated in a more recently published work [1]. Studies conducted under simulated physiological conditions (pH 7.4, 37 °C) were unsuccessful due to adsorption onto the capillary wall in both coated and uncoated capillaries. Studies conducted at pH 9.2 indicated that there are weak interactions between PNaA analogues and serum proteins. The potential of isotachophoresis (ITP) for development of a new cell count method for mammalian cells was also investigated. Studies determined that poly(N‐vinyl pyrrolidone) (PVP) was an insufficient capillary coating for migrations conducted in a 250 μm i.d. capillary, with stripping of the coating occurring at both coating concentrations (1 % and 3 % PVP) used. The preliminary work conducted in this study suggests that ITP has the potential to be used as a cell count method for mammalian cells, as cells were successfully injected and migrated in this study. This work opens the way to determine the potential of PAA/PNaA as a drug delivery system.
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Chan, Chi-Ming, and 詹騏銘. "Drug Release Behavior of Hydrogel Membrane composites based on Poly(vinyl alcohol)/Poly(acrylic acid)." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/42751356636719015162.
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碩士國立中興大學
化學系所
97
Smart hydrogel, the semi-interpenetration polymer network system (semi-IPNs) composed of pH-sensitive polyacrylic acid (PAA) trapped with polyvinyl alcohol (PVA) in the present of glutaraldehyde (GA) as the cross-linker, is prepared for application in drug delivery of Acetaminophen. The structure and properties of as-produced hydrogels were investigated by Fourier transform infrared (FT-IR) analysis, Differential Scanning Calorimetry (DSC), X-ray diffraction pattern (XRD). Swelling rate of PVA hydrogels is inversely proportional to the cross-linker density, indicating the drug release rate from such hydrogels is determined by a density of the net and is lowered by a increase in the PVA : GA mass ratio. The swelling behaviors of PVA/PAA hydrogels and drug release from the hydrogels in relation to pH were investigated. As in neutral environment, the swelling velocity was much improved by introducing PAA in comparison with non-PAA, which is due to the enhancement of the entanglement of this hydrogel network resulted from electrostatic repulsive interaction of carboxylic (COO-) group. It indicated that the PAA introduced hydrogel system provided a suitable release profile for drug delivery vehicle.
50
Ping-LunHsieh and 謝秉倫. "Redox- and pH-responsive complex micelles assembled from saccharide- and lipoic acid-modified poly(L-lysine) and poly(acrylic acid)." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/29332415563334527584.
Full textAbstract:
碩士國立成功大學
化學工程學系碩博士班
101
In this study, novel pH and redox-responsive, cellular targeting polyelectrolyte complex (PEC) particles were developed. By mixing the polycation and polyanion, lactobionolatone modified poly(L-lysine)-graft-lipoic acid (PLL-g-Lipo-g-Lac) and poly acrylic acid (PAA), PEC particles can be formed with excess polyelectrolyte and saccharide group on the corona. PLL polypeptides were prepared by synthesizing poly(Z-L-lysine) (PZLL) via ring-opening polymerization (ROP) from Z-L-lysine N-carboxyanhydrides (NCAs) and subsequently removing the protecting Z group. PLL-g-Lipo-g-Lac graft copolypeptides with different polypeptide chain lengths and grafting degrees of lipoic acid were synthesized. The grafting degrees of lipoic acid and saccharide group were determined by Nuclear Magnetic Resonance Spectrophotometer (NMR). The size, charge, chain conformation, and morphology of the as-prepared PEC particles at different solution conditions were characterized by dynamic light scattering (DLS), aqueous electrophoresis, transmission electron microscopy (TEM) and circular dichroism (CD) measurements. The positively and negatively charged PEC particles with size ranged between 50 and 200 nm can be prepared by varying polymer chain length, grafting degree, and composition. The experimental data revealed that these PEC particles can response to the pH and oxidation/reduction changes in the environment. The selective lectin binding experiments confirmed that the galactose units on the particles can be used in biorecognition applications. Combining their dual-response and liver cell targeting ability, these PEC particles could be useful in biomedical fields such as drug delivery.