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Dissertations / Theses on the topic 'Polymer colloids'
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1
Quarcoo, Naa Larteokor. "Modeling polymer-colloid phase behavior." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 152 p, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1440615.
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Köhler, Werner. "Hot colloids in polymer networks." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-179496.
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Cohen, Jack Andrew. "Active colloids and polymer translocation." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:e8fd2e5d-f96f-4f75-8be8-fc506155aa0f.
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This thesis considers two areas of research in non-equilibrium soft matter at the mesoscale. In the first part we introduce active colloids in the context of active matter and focus on the particular case of phoretic colloids. The general theory of phoresis is presented along with an expression for the phoretic velocity of a colloid and its rotational diffusion in two and three dimensions. We introduce a model for thermally active colloids that absorb light and emit heat and propel through thermophoresis. Using this model we develop the equations of motion for their collective dynamics and consider excluded volume through a lattice gas formalism. Solutions to the thermoattractive collective dynamics are studied in one dimension analytically and numerically. A few numerical results are presented for the collective dynamics in two dimensions. We simulate an unconfined system of thermally active colloids under directed illumination with simple projection based geometric optics. This system self-organises into a comet-like swarm and exhibits a wide range of non- equilibrium phenomena. In the second part we review the background of polymer translocation, including key experiments, theoretical progress and simulation studies. We present, discuss and use a common model to investigate the potential of patterned nanopores for stochastic sensing and identification of polynucleotides and other heteropolymers. Three pore patterns are characterised in terms of the response of a homopolymer with varying attractive affinity. This is extended to simple periodic block co-polymer heterostructures and a model device is proposed and demonstrated with two stochastic sensing algorithms. We find that mul- tiple sequential measurements of the translocation time is sufficient for identification with high accuracy. Motivated by fluctuating biological channels and the prospect of frequency based selectivity we investigate the response of a homopolymer through a pore that has a time dependent geometry. We show that a time dependent mobility can capture many features of the frequency response.
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Golz, Paul Michael. "Dynamics of colloids in polymer solutions." Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/10922.
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The dynamics of a dilute suspension of colloids diffusing in a simple liquid are well understood and are characterised by the Stokes-Einstein equation. However the validity of this equation for describing the diffusion of a colloid through a polymer solution has been questioned. In this work the motion of dilute poly-methylmethacrylate spheres diffusing through a solution of flexible polystyrene polymers has been studied. Dynamic light scattering was used to measure the self-diffusion of the spheres and the diffusion coefficient for this motion was found to exhibit time dependence. At short times the colloid moves faster than expected from a simple 'polymer solution as a continuum' assumption whereas at longer times this assumption appears valid. Solutions with polymer concentrations up to half the overlap concentration were investigated: the ratio of short to long time diffusion Ds/DL was found to increase with concentration. The effect of changing the quality of the solvent from theta to good was also investigated and no qualitative difference was found. In these experiments it was found that the effect of scattering from the polymer was more significant that initially expected. In particular, the presence of cross scattering, in which the electric field scattered from the colloid is correlated with that from the polymer, can be as high as 30%, despite the polymer scattering being only a few percent. A method for both calculating and experimentally measuring the magnitude of the cross scattering has been described. A new experimental methodology is proposed to minimise the cross and polymer scattering, allowing for measurement of the colloid scattering alone.
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Green, Nicholas David. "Investigating clay-nonionic polymer interactions." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389120.
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Mahaffy, Rachel Elaine. "The quantitative characterization of the viscoelastic properties of cells and polymer gels /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004328.
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Chen, Yuanye. "Synthesis and Study of Engineered Heterogenous Polymer Gels." Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc278503/.
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This dissertation studies physical properties and technological applications of engineered heterogenous polymer gels. Such gels are synthesized based on modulation of gel chemical nature in space. The shape memory gels have been developed in this study by using the modulated gel technology. At room temperature, they form a straight line. As the temperature is increased, they spontaneously bend or curl into a predetermined shape such as a letter of the alphabet, a numerical number, a spiral, a square, or a fish. The shape changes are reversible. The heterogenous structures have been also obtained on the gel surface. The central idea is to cover a dehydrated gel surface with a patterned mask, then to sputter-deposit a gold film onto it. After removing the mask, a gold pattern is left on the gel surface. Periodical surface array can serve as gratings to diffract light. The grating constant can be continuously changed by the external environmental stimuli such as temperature and electric field. Several applications of gels with periodic surface arrays as sensors for measuring gel swelling ratio, internal strain under an uniaxial stress, and shear modulus have been demonstrated. The porous NIPA gels have been synthesized by suspension technique. Microstructures of newly synthesized gels are characterized by both SEM and capillary test and are related to their swelling and mechanical properties. The heterogenous porous NIPA gel shrink about 35,000 times faster than its counterpart--the homogeneous NIPA gel. Development of such fast responsive gels can result in sensors and devices applications. A new gel system with built-in anisotropy is studied. This gel system consists of interpenetrated polymer network (IPN) gels of polyacrylamide (PAAM) and N-isopropylacrylamide (NIPA). The swelling property of the anisotropy IPN gels along the pre-stressing direction is different from that along other directions, in contrast to conventional gels which swell isotropically. It is found that the ratio (L/D) of length (L) and diameter (D) of IPN samples has step-wise changes as the samples are heated from below the volume phase transition temperature to the above. A theoretical model is proposed and is in good agreement with the experimental results.
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Liang, Ya Palmese Giuseppe R. Lowman Anthony M. "Functional polymer-polymer composites by nano/meso-fiber encapsulation : applications in drug delivery systems and polymer toughening /." Philadelphia, Pa. : Drexel University, 2010. http://hdl.handle.net/1860/3316.
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Wu, Lin. "Synthesis, modification and applications of polymer colloids." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581974.
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Three approaches were used for the preparation of polymer colloids, including block copolymer micellization, miniemulsion and dispersion polymerisation. Polymers, ego PDMAEMA, PDMAEMA-b-PBMA, P(PDMA-PS)4, P(PS-PDMA)4, involved in the preparation were synthesized using reversible addition fragmentation chain transfer (RAFT) polymerisation. The details of each approach are given below. In the first approach, well-defined amphiphilic star block copolymers, P-(PS- PDMA)4 and P-(PDMA-PS)4 (P: porphyrin) were prepared from a free base porphyrin-cored chain transfer agent (CTA-FBP) and used for self-assembly studies. In methanol, a selective solvent for PDMA, spherical micelles were observed for both block copolymers, as characterized by TEM. UV-VIS studies suggested that star-like micelles were formed from P-(PS-PDMA)4, while P-(PDMA-PS)4 aggregated into flower-like micelles. In the second approach, miniemulsions, prepared using PDMAEMA-b-PBMA or PDMAEMA polymers were used as templates for the synthesis of polymer nanocapsules via the quaternization cross-linking of PDMAEMA (block), using 1, 2- bis(2-iodoethoxy)ethane (BIEE) as a bifunctional crosslinker. The miniemulsion prepared from block copolymers of PDMAEMA-b-PBMA were used as templates for the synthesis of Prussian Blue nanoshells, while cross-linked PDMAEMA homopolymer miniemulsions were used as capsules for hydrophobic dyes. In the last approach, PDMS-CTAs (poly(dimethylsiloxane)-based chain transfer agents) were prepared and used as stabilizers in the dispersion polymerisation of methyl methacrylate (MMA) in hexane. The effect of several factors, including the molecular weight of the PDMS and the concentration of the initiator, on the MMA polymerisation was investigated. The kinetics of the polymerisation in the presence of two CTAs were also investigated.
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Steward, Paul A. "Modification of the permeability of polymer latex films." Thesis, Nottingham Trent University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296030.
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Higginbotham, Catrena Pearl. "The characterization and manipulation of the internal pore structure of tetramethoxysilane sol-gels and polymer hybrid gels." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/30556.
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Ramírez, Ríos Liliana Patricia. "Superpara- and paramagnetic polymer colloids by miniemulsion processes." [S.l. : s.n.], 2004. http://pub.ub.uni-potsdam.de/2004/0026/ramirez.pdf.
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Ramírez, Ríos Liliana Patricia. "Superpara- and paramagnetic polymer colloids by miniemulsion processes." Phd thesis, Universität Potsdam, 2004. http://opus.kobv.de/ubp/volltexte/2005/137/.
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Polymerverkapselte magnetische Nanopartikel versprechen, in der Zukunft sehr erfolgreich bei Anwendungen in der Biologie und der Medizin eingesetzt werden zu können z. B. in der Krebstherapie und als Kontrastmittel bei der magnetischen Kernspinresonanztomographie. Diese Arbeit zeigt, dass durch die interdisziplinäre Kombination verschiedener Techniken Herstellungsverfahren und Eigenschaften solcher Partikel verbessert werden können. Unter Miniemulsionen versteht man wässrige Dispersionen relativ stabiler Öltröpfchen, zwischen 30 und 50 nm Größe. Ein Nanometer (nm) ist der 1.000.000.000ste Teil eines Meters. Ein Haar ist ungefähr 60.000 Nanometer breit.
Hergestellt werden Miniemulsionen durch Scherung eines Systems bestehend aus Öl, Wasser, Tensid (Seife) und einer weiteren Komponente, dem Hydrophob, das die Tröpfchen stabilisieren soll. Die Polymerisation von Miniemulsionen ermöglicht die Verkapselung anorganischer Materialen z. B. magnetischer Teilchen oder Gadolinium-haltiger Komponenten. Zu Optimierung des Verkapselung, ist es notwendig, die richtige Menge eines geeigneten Tensids zu finden.
Die magnetischen polymerverkapselten Nanopartikel, die in einer wässrigen Trägerflüssigkeit dispergiert sind, zeigen in Abhängigkeit von Partikelgröße, Zusammensetzung, elektronischer Beschaffenheit, etc. ein sogenanntes superpara- oder paramagnetisches Verhalten. Superpara- oder paramagnetisches Verhalten bedeutet, dass die Flüssigkeiten in Anwesenheit äußerer Magnetfeldern ihre Fließfähigkeit beibehalten. Wenn das Magnetfeld entfernt wird, haben sie keine Erinnerung mehr daran, unter dem Einfluss eines Magnetfeldes gestanden zu haben, d. h., dass sie nach Abschalten des Magnetfeldes selbst nicht mehr magnetisch sind.
Die Vorteile des Miniemulsionsverfahrens sind der hohe Gehalt und die homogene Verteilung magnetischer Teilchen in den einzelnen Nanopartikeln. Außerdem ermöglicht dieses Verfahren nanostrukturierte Kompositpartikel herzustellen, wie z. B polymerverkapselte Nanopartikel mit Nanoschichten bestehend aus magnetischen Molekülen.
Combining the magnetic properties of a given material with the tremendous advantages of colloids can exponentially increase the advantages of both systems. This thesis deals with the field of magnetic nanotechnology. Thus, the design and characterization of new magnetic colloids with fascinating properties compared with the bulk materials is presented.
Ferrofluids are referred to either as water or organic stable dispersions of superparamagnetic nanoparticles which respond to the application of an external magnetic field but lose their magnetization in the absence of a magnetic field.
In the first part of this thesis, a three-step synthesis for the fabrication of a novel water-based ferrofluid is presented. The encapsulation of high amounts of magnetite into polystyrene particles can efficiently be achieved by a new process including two miniemulsion processes. The ferrofluids consist of novel magnetite polystyrene nanoparticles dispersed in water which are obtained by three-step process including coprecipitation of magnetite, its hydrophobization and further surfactant coating to enable the redispersion in water and the posterior encapsulation into polystyrene by miniemulsion polymerization. It is a desire to take advantage of a potential thermodynamic control for the design of nanoparticles, and the concept of "nanoreactors" where the essential ingredients for the formation of the nanoparticles are already in the beginning. The formulation and application of polymer particles and hybrid particles composed of polymeric and magnetic material is of high interest for biomedical applications. Ferrofluids can for instance be used in medicine for cancer therapy and magnetic resonance imaging.
Superparamagnetic or paramagnetic colloids containing iron or gadolinium are also used as magnetic resonance imaging contrast agent, for example as a important tool in the diagnosis of cancer, since they enhance the relaxation of the water of the neighbouring zones. New nanostructured composites by the thermal decomposition of iron pentacarbonyl in the monomer phase and thereafter the formation of paramagnetic nanocomposites by miniemulsion polymerization are discussed in the second part of this thesis. In order to obtain the confined paramagnetic nanocomposites a two-step process was used. In the first step, the thermal decomposition of the iron pentacarbonyl was obtained in the monomer phase using oleic acid as stabilizer. In the second step, this iron-containing monomer dispersion was used for making a miniemulsion polymerization thereof.
The addition of lanthanide complexes to ester-containing monomers such as butyl acrylate and subsequent polymerization leading to the spontaneous formation of highly organized layered nanocomposites is presented in the final part of this thesis. By an one-step miniemulsion process, the formation of a lamellar structure within the polymer nanoparticles is achieved. The magnetization and the NMR relaxation measurements have shown these new layered nanocomposites to be very apt for application as contrast agent in magnetic resonance imaging.
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Hibberd, David. "Use of ultrasound to characterise polymer induced flocculation." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267709.
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Popovic, Suzana. "Design of electro-active polymer gels as actuator materials /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/7053.
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Qi, Zhigang. "Synthesis of conducting polymer colloids, hollow nanoparticles, and nanofibers." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40229.
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Colloidal polypyrrole and polyaniline stabilized by anionic surfactants were prepared and characterized. A "pseudo-micelle" model has been proposed. The aggregation of pseudo-micelles on the forming polymer chains is believed to be the key step in the stabilization process. Only when the aggregation is possible and fast enough to follow the polymer formation, will the polymer be stabilized.Colloidal polypyrrole and polyaniline were prepared in the presence of the sodium salt of poly(styrene sulfonate). The polymerization is believed to follow a template-guided fashion in which poly(styrene sulfonate) functions as a molecular template for pyrrole and aniline polymerization. The stability and water solubility of the colloids are attributed to the presence of excess poly(styrene sulfonate) sulfonate groups in the resulting complexes.
It was found that the chemical polymerization of pyrrole is catalyzed by anionic surfactants and polyelectrolytes. The catalysis is believed to arise from the accumulation of protons, neutral pyrrole monomer and oligomers, and their radical cations in the micellar or polyelectrolyte pseudophase via electrostatic and hydrophobic interactions. Nucleation was found to be a necessary and important step in the chemical polymerization of conducting polyaniline and polypyrole. A nucleation process has been proposed. A polyaniline-polypyrrole graft- or block-copolymer was produced by adding colloidal PANI to a similar amount of pyrrole.
Hollow conducting polypyrrole nanoparticles with diameters of ca. 140 nm or 60 nm and wall thicknesses of ca. 10 nm were fabricated. The shape and size of the hollow particles are determined by the core particles and the wall thickness is controlled by reaction conditions. A $ gamma$-Fe$ rm sb2O sb3$-polypyrrole composite possessing both magnetic and electrically conductive properties was also produced.
Polypyrrole and polyaniline nanofibers with highly uniform diameters between 10 and 50 nm were fabricated via the templating by lipid microstructures. The hydrophobic edges of the lipid microstructures function as the template. The polymer thickness is readily controlled by the polymerization time. Well-defined conducting polymer nano-rings were also produced.
Finally, the sensitivity enhancement of the electroanalysis of halides through the accumulation of trihalides in an overoxidized polypyrrole film was presented. This reveals a new method of using polymer-modified electrodes in electroanalysis, and we term the accumulation of a reaction product "product concentration".
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Zholobko, Oksana. "Functional Colloids from Amphiphilic Polymer Assemblies and Peptides/Polypeptides." Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/29963.
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The use of responsive polymers, where even minor changes in one of the macromolecular characteristics triggered by the external stimuli can cause drastic changes in the material function or performance, is widely studying area of research. Formation of the thermodynamically stable polymer-peptide colloids, such as mixed micellar assemblies or polymer-enzyme conjugates, loading capacity of the colloids, and cargo activity all depend on the macromolecular interactions within the peptide/polypeptide-polymer system. The goal of this work is to investigate interactions between range of new polymers and various cargo molecules and determine whether those interactions affect the physicochemical properties of the resulted colloids. For this purpose, two types of colloid systems were explored: i) peptide-loaded invertible micellar assemblies (IMAs), formed using hydrophobic interactions between amphiphilic invertible polymers (AIP) and peptides (HA, V5, or peptide-based vaccine), and ii) polymeric cellulosomes made from polymer ligand (PL), copolymer of glycidyl methacrylate (GMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) and mixture of cellulases, using covalent bonding. The purpose of the research was to evaluate if colloids properties are affected by changes in responsive polymer characteristics as well as if the developed macromolecular structure and composition need further synthetic modification/optimization. AIP-related part of this dissertation is focused on i) understanding of interaction between peptides and AIPs, and formation of mixed micellar assemblies; ii) further behavior of cargo peptide molecules in the micellar interior under the AIP conformational changes, triggered by IMAs localization at polar and nonpolar interface; iii) evaluation of the impact of IMAs on model lipid membrane diffusivity and permeability. Besides, AIP-peptide assemblies were tested in vitro and in vivo in order to evaluate the cargo delivery, antibody response, and immunity protection in vaccinated pigs against Swine influenza viruses (SIV). To explore the feasibility of covalent bonding in formation of responsive polymer-based colloids, enzyme-polymer conjugates (EPCs) were designed and their enzymatic catalytic activity for the biomass hydrolysis was further tested. The effect of conjugation on catalytic activity, conjugation efficiency, glucose inhibition effect, type of substrate, and type of biomass pretreatment were evaluated and compared to free enzymes.North Dakota. Department of Commerce
National Science Foundation (U.S.)
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Garner, Brett William Neogi Arup. "Multifunctional organic-inorganic hybrid nanophotonic devices." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-6108.
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Jia, Zichen. "Stability, aggregation kinetics and aggregates thermal restructuring of polymer colloids /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16913.
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Wilkinson, Terence Sean. "Photophysical studies of waterborne polymer colloids and their film formation." Thesis, Lancaster University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302429.
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Ma, Yanhui. "Graft copolymer micelles and surface modification with polymer micelles /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Vandoolaeghe, Wendy Leigh. "Polymer networks at surfaces." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53552.
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Thesis (MSc)--Stellenbosch University, 2003.ENGLISH ABSTRACT: In this thesis the formation and properties of a polymer gel on and at a surface are investigated. The gel under investigation is defined as a three-dimensional network of macromolecules that form permanent links with one another and also with confining planar surfaces. The precise location of the crosslinks on the wall or on another macromolecule is not known prior to linking, and will differ from sample to sample. However, once the crosslinks are formed, they are assumed to be permanent. This random linking is the source of the disorder in the system, over which a quenched average has to be taken. An existing model [9] of network formation, with polymer-polymer crosslinks, is extended to incorporate a surface and polymersurface crosslinks. Within the framework of replica theory, statistical averages and physical properties of the system are calculated by means of a variational approach. Macroscopic information, in terms of the free energy of deformation, is obtained by using two different potentials to simulate the erosslinks mathematically.
AFRIKAANSE OPSOMMING: In hierdie tesis word die vorming en eienskappe van 'n polimeergel, wat teen 'n oppervlak gevorm word, ondersoek. Die gel word gedefinieer as 'n drie-dimensionele netwerk van makromolekules wat permanente bindings met mekaar, maar ook met twee inperkende, platvlakke, vorm. Die presiese ligging van die bindings op die muur en op ander makromolekules is nie vooraf bekend nie, en sal verskil van een gel-monster tot die volgende. Sodra die konneksies egter gevorm is, word aanvaar dat hulle permanent is. Die lukrake bindingsproses is die oorsprong van wanorde in die sisteem, waaroor 'n wanorde-gemiddelde bereken moet word. 'n Bestaande model [9]van netwerkvorming, met polimeer-polimeer bindings, word uitgebrei om 'n oppervlakte en polimeer-oppervlak bindings in te sluit. Statistiese fisika gemiddeldes en fisiese eienskappe van die sisteem word binne die raamwerk van replika-teorie en 'n variasie benadering bereken. Makroskopiese inligting, in terme van die vrye energie van vervorming, word verkry deur twee verskillende potensiale te gebruik om die konneksies wiskundig voor te stel.
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Abbott, Nicholas L. (Nicholas Lawrence). "Interactions of flexible polymers and globular colloids : understanding protein partitioning in two-phase aqueous polymer systems." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/82741.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1992.Science hard copy is bound in 1 v.
Includes bibliographical references (leaves 364-377).
by Nicholas L. Abbott.
Ph.D.
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Hunt, Paul Edward. "Protective colloids : understanding nucleation and grafting." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/protective-colloids-understanding-nucleation-and-grafting(a5f5c8c9-acc7-492b-bf81-3cf327af98cf).html.
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Alkali-soluble resins (ASRs) were prepared by (i) solution and (ii) emulsion polymerization. All ASRs were synthesized with number-average molar masses < 20,000 g mol-1 and all had 15 wt% methacrylic acid 5 wt% styrene, the remaining 80 wt% was composed of either methyl methacrylate or a combination of methyl methacrylate and ethyl acrylate. All emulsion ASRs were made to 20% solids, with volume-average particle diameters (dv) in the region 30 – 50 nm, with a glass transition temperature of 80 – 120 °C. Emulsion polymerization was the preferred route for ASR synthesis, to allow further studies on their dissolution behaviour. Before their use as colloidal stabilizers, the dissolution behaviour of the ASRs needed to beinvestigated e.g. effect of temperature, molar mass, and composition. Particle size and absorbance measurements were taken during dissolution of ASRs to achieve 100%neutralization and these were shown to have two stages, an apparent particle swelling (whichwas rapid), and a slower, decrease in particle size as water-soluble polymeric material wasdiffusing out of the ASR particles. From this, further interpretation allowed for calculating the diffusion coefficient of the ASR polymer using the Stokes-Einstein equation. Time-domain nuclear magnetic resonance (TD-NMR) was employed to enhance understanding of what is occurring in the ASR particles, and in the aqueous, continuous phase. The final aspect of this project was to use the ASRs prepared as colloidal stabilizers in emulsion polymerizations of butyl acrylate (BA) and butyl methacrylate (BMA) using varying levels and also the effect of adding additional surfactant. The results show that the effect of ASR molar mass, the concentration of stabilizer, and also the impact of the EA-containing ASR greatly influence stability, whereby lower ASR molar mass, higher levels of stabilizer and including EA greatly benefit colloidal stability in PBA latexes. In PBMA latexes, a similar trend was also observed, but, the presence of ethyl acrylate (EA) in the ASR backbone has a detrimental effect on the colloidal stability, caused by the inability of grafting to occur between the ASR and PBMA.
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Di, Dio Bruno Flavio. "Time-dependent rheology of soft particle glasses." Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLS026.
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Comportement rhéologique dépendant du temps dans les verres colloïdaux de particules déformablesNous étudions des verres colloïdaux constitués de suspensions denses de particules déformables dans un fluide suspendant. Des exemples pratiques comprennent beaucoup de matériaux pâteux tels que les encres solides, les produits de soins personnels et certaines préparations alimentaires. Ces matériaux se comportent comme des fluides à seuil d’écoulement qui répondent de façon élastique à des petites déformations mais s’écoulent au-delà d’une contrainte seuil. Beaucoup de travaux expérimentaux et théoriques ont étudié leurs propriétés rhéologiques à l’état stationnaire. Les connaissances sur la réponse transitoire lors de la mise en écoulement ou au contraire lors de l’arrêt sont beaucoup moins avancées.Nous abordons ce problème dans le cas de suspensions très concentrées de microgels polyélectrolytes dont la microstructure est bien caractérisée. Sous écoulement ces verres colloïdaux accumulent des contraintes internes d’origine élastique qui relaxent très lentement de sorte qu’ils conservent au repos la mémoire de la direction dans laquelle ils ont été cisaillés. Nous proposons plusieurs protocoles de préparation qui minimisent l’effet de ces contraintes résiduelles et permettent de réaliser des expériences dénuées de biais directionnels. Les contraintes transitoires associées à la mise en écoulement sont analysées à l’aide d’expériences systématiques, de simulations, et d’un modèle phénoménologique, à la fois pour des microgels répulsifs et associatifs. Un dernier chapitre est consacré aux propriétés viscoélastiques à haute fréquence des suspensions. Nos résultats démontrent le rôle clé de la compétition entre l’élasticité due aux interactions de contact et les forces de viscosité dans le fluide suspendant. Ceci nous permet de proposer un cadre conceptuel qui rationalise les comportements dépendants du temps des verres colloïdaux de particules déformablesTime-dependent rheology of soft particle glassesSoft particle glasses are jammed suspensions of soft and deformable particles dispersed in a viscous fluid. Common examples include pasty materials such as solid inks, personal care products, and foods. They behave as yield stress fluids, which respond elastically to small perturbations, but deform irreversibly and flow when they are subjected to large enough stresses. Many experimental and theoretical studies have focused on the steady shear rheology of these materials. However much less is known about their behavior in transient situations like flow cessation or startup flow.Here we investigate the time-dependent rheology of jammed suspensions made of well-characterized polyelectrolyte microgels. Upon flow cessation, these materials store residual stresses that relax very slowly and are responsible for long-lived directional memory and aging. We design several experimental protocols that minimize residual stresses and memory making it possible to perform startup experiments without directional bias. The behavior of the stress growth function is then analyzed and discussed using systematic experiments, simulations, and a phenomenological model for microgels with both repulsive interactions and short-range associations. A final chapter is devoted to the high-frequency linear viscoelasticity of the suspensions. Overall, our results demonstrate the key role played by the competition between elastic contact forces and viscous forces, thus providing a unifying framework to rationalize the time-dependent rheology of soft particle glasses
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Köhler, Werner. "Hot colloids in polymer networks: cage formation and transient network deformation." Diffusion fundamentals 20 (2013) 13, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13535.
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Pirie, Angus D. "A light scattering study of colloid-polymer mixtures." Thesis, University of Edinburgh, 1995. http://webex.lib.ed.ac.uk/homes/pirie95.html.
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Li, Chʻun-fang. "Scaling Behaviors and Mechanical Properties of Polymer Gels." Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc279278/.
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Polymer gels undergo a volume phase transition in solvent in response to an infinitesimal environmental change. This remarkable phenomenon has resulted in many potential applications of polymer gels. The understanding of its mechanical properties has both scientific and technological importance. For this purpose, we have developed a novel method for measuring Poisson's ratio, which is one of the most important parameters determining the mechanical property of gels. Using this method, Poisson's ratio in N-isopropyacrylamide (NIPA) and polyacrylamide (PAAM) gels has been studied.
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Lee, Jung-Hyun. "Interface engineering in zeolite-polymer and metal-polymer hybrid materials." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37120.
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Inorganic-polymer hybrid materials have a high potential to enable major advances in material performance in a wide range of applications. This research focuses on characterizing and tailoring the physics and chemistry of inorganic-polymer interfaces in fabricating high-performance zeolite-polymer mixed-matrix membranes for energy-efficient gas separations. In addition, the topic of novel metal nanoparticle-coated polymer microspheres for optical applications is treated in the Appendix.
In zeolite/polymer mixed-matrix membranes, interfacial adhesion and interactions between dope components (zeolite, polymer and solution) play a crucial role in determining interfacial morphology and particle dispersion. The overarching goal is to develop accurate and robust tools for evaluating adhesion and interactions at zeolite-polymer and zeolite-zeolite interfaces in mixed-matrix membrane systems. This knowledge will be used ultimately for selecting proper materials and predicting their performance. This project has two specific goals: (1) development of an AFM methodology for characterizing interfacial interactions and (2) characterization of the mechanical, thermal, and structural properties of zeolite-polymer composites and their correlation to the zeolite-polymer interface and membrane performance. The research successfully developed an AFM methodology to determine interfacial interactions, and these were shown to correlate well with polymer composite properties. The medium effect on interactions between components was studied. We found that the interactions between two hydrophilic silica surfaces in pure liquid (water or NMP) were described qualitatively by the DLVO theory. However, the interactions in NMP-water mixtures were shown to involve non-DLVO forces arising from bridging of NMP macroclusters on the hydrophilic silica surfaces. The mechanism by which nanostructured zeolite surfaces enhanced in zeolite-polymer interfacial adhesion was demonstrated to be reduced entropy penalties for polymer adsorption and increased contact area.
¡¡¡¡¡¡Metal nanoparticle (NP)-coated polymer microspheres have attracted intense interest due to diverse applications in medical imaging and biomolecular sensing. The goal of this project is to develop a facile preparation method of metal-coated polymer beads by controlling metal-polymer interactions. We developed and optimized a novel solvent-controlled, combined swelling-heteroaggregation (CSH) technique. The mechanism governing metal-polymer interaction in the fabrication was determined to be solvent-controlled heteroaggregation and entanglement of NPs with polymer, and the optical properties of the metal/polymer composite beads were shown to make them useful for scattering contrast agent for biomedical imaging and SERS (Surface-Enhanced Raman Scattering) substrates.
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Sun, Zhengfei Wei Yen. "Novel sol-gel nanoporous materials, nanocomposites and their applications in bioscience /." Philadelphia, Pa. : Drexel University, 2005. http://dspace.library.drexel.edu/handle/1860/556.
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Saw, Lin K. "Phase inversion in polyurethane prepolymer-water dispersions." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/15350.
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Aqueous polyuethane (PU) colloids, like many other water-borne polymer colloids, have become an increasingly important class of materials in the surface coating industry. Three processing stages, the pre-dispersion, dispersion and postdispersion stages, are generally involved in the production of aqueous PU colloids. However, existing researches have neglected the importance of the dispersion stage. The present study aims to develop better understanding of the dispersion stage during the production of aqueous PU colloids. Non chain-extendable PU pre-polymer (PUp) is used to enable independent study of the dispersion stage and the phase inversion process is chosen due to its widespread industrial usage. Valid drop size characterisation techniques and phase inversion detection methods have been developed in this project. Three different dispersion regions have also been identified by changing the ionic group content of PUp. Each dispersion region is associated with a particular dispersion type. Those are (I) Stable aqueous emulsions that contain small PUp-in-water drops. They were produced using PUp with more than 0.2 mmole/g of ionic groups. (2) Aqueous PUp colloids with 0.05 ~ 0.2 mmole/g of ionic groups. These emulsions contain a mixture of drop structures, including simple drops and different multiple drops. (3) Aqueous PUp dispersions containing less than 0.05 mmole/g of ionic groups. These dispersions are not stable and the resultant dispersions separated when agitation was stopped. Modified phase inversion maps are introduced to represent the occurrence of all three dispersion regions. The modified phase inversion maps are partly analogous to those of conventional non-ionic-surfactant-water (nSOW) systems. The three dispersion regions have also been "reproduced" successfully using external surfactants as substitutes for the internal stabilising groups. A new catastrophic phase inversion mechanism is proposed to explain the existence of all three dispersion regions. Other variables studied during this project include different neutralising agents. different amount of carboxylic acid groups, operating temperatures and material addition rates. In conclusion, this project shows that the phase inversion process is a feasible route for producing aqueous polymer dispersions with little or no added external surfactants. Stable PUp-W dispersions can also be produced below the minimum ionic group content reported in existing literatures.
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Zhou, Jun Hu Zhibing. "Stimuli-responsive microgels for self-assembled crystalline structures and controlled drug release." [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/permalink/meta-dc-11001.
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Lu, Xihua. "Polymer hydrogel nanoparticles and their networks." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3232/.
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The thermally responsive hydroxypropyl cellulose (HPC) hydrogel nanoparticles have been synthesized and characterized. The HPC particles were obtained by chemically crosslinking collapsed HPC polymer chains in water-surfactant (dodecyltrimethylammonium bromide) dispersion above the lower critical solution temperature (LCST) of the HPC. The size distributions of microgel particles, measured by dynamic light scattering, have been correlated with synthesis conditions including surfactant concentration, polymer concentration, and reaction temperature. The swelling and phase transition properties of resultant HPC microgels have been analyzed using both static and dynamic light scattering techniques. By first making gel nanoparticles and then covalently bonding them together, we have engineered a new class of gels with two levels of structural hierarchy: the primary network is crosslinked polymer chains in each individual particle, while the secondary network is a system of crosslinked nanoparticles. The covalent bonding contributes to the structural stability of the nanostructured gels, while self-assembly provides them with crystal structures that diffract light, resulting in colors. By using N-isopropylacrylamide copolymer hydrogel nanoparticles, we have synthesized nanoparticle networks that display a striking iridescence like precious opal but are soft and flexible like gelatin. This is in contrast to previous colored hydrogels, which were created either by adding dyes or fluorescent, or by organic solvent or by embedding a colloidal crystal array of polymer solid spheres . Creating such periodic 3D structures in materials allows us to obtain useful functionality not only from the constituent building blocks but also from the long-range ordering that characterizes these structures. Hydroxypropyl cellulose (HPC) and poly (acrylic acid ) (PAA) complexes were studied using turbidity measurement and laser light scattering. The phase transition temperature of the complexes is found to depend on pH and molecular weights of PAA and HPC. The driving force for this phenomenon is due to the hydrogen bonding and hydrophobic interaction of the macromolecules. Based on the principle of the PAA/HPC complexes, the PAA nanoparticles were synthesized in 0.1wt % HPC aqueous solution at room temperature.
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Dumetz, Andre C. "Protein interactions and phase behavior in aqueous solutions effects of salt, polymer, and organic additives /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 284 p, 2008. http://proquest.umi.com/pqdweb?did=1456290971&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Thesis (Ph.D.)--University of Delaware, 2007.Principal faculty advisor: Abraham M. Lenhoff, Dept. of Chemical Engineering, and Eric W. Kaler, College of Engineering . Includes bibliographical references.
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Downey, Jeffrey S. "Precipitation polymerization of divinylbenzene to monodisperse microspheres : an investigation of the particle formation mechanism /." *McMaster only, 2000.
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Choi, Ming Fai. "Design and synthesis of coordination polymer gels and high dichroic ratio azo dyes /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202002%20CHOI.
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Zhou, Bo. "The preparation and characterization of thermo-sensitive colored hydrogel film and surfactant-free porous polystyrene three-dimensional network." Thesis, University of North Texas, 2001. https://digital.library.unt.edu/ark:/67531/metadc3019/.
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Polymer hydrogel films change their properties in response to environmental change. This remarkable phenomenon results in many potential applications of polymer hydrogel films. In this thesis colored thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogel film was prepared by firstly synthesizing polymer latex and secondarily crosslinking the nanoparticles and casting the polymers onto glass. The shape-memory effect has been observed when changing the environmental temperature. The temperature-dependent of turbidity of polymer hydrogel film was measured by HP UVVisible spectrophotometer. This intelligent hydrogel might be used in chemomechanical systems and separation devices as well as sensors. Polymer adsorption plays an important role in many products and processes. In this thesis, surfactant-free three-dimensional polystyrene (PS) nanoparticle network has been prepared. The infrared spectroscopy and solubility experiment are performed to prove the crosslinking mechanism, also the BET method was used to measure the adsorption and desorption of polystyrene network. The BET constant (C) is calculated (C=6.32). The chemically bonded polymer nanoparticle network might have potential applications as catalyst or used for chromatographic columns.
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Nasakul, Siree. "Thermoreversible gels and temperature triggered kinetically controlled gels for oilfield applications /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Walther, Andreas. "Soft compartmentalized polymer colloids : janus particles, multicompartment structures, inorganic-organic hybrids and applications." kostenfrei, 2008. http://opus.ub.uni-bayreuth.de/volltexte/2008/496/.
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Quant, Carlos Arturo. "Colloidal chemical potential in attractive nanoparticle-polymer mixtures: simulation and membrane osmometry." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7616.
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The potential applications of dispersed and self-assembled nanoparticles depend critically on accurate control and prediction of their phase behavior. The chemical potential is essential in describing the equilibrium distribution of all components present in every phase of a system and is useful as a building block for constructing phase diagrams. Furthermore, the chemical potential is a sensitive indicator of the local environment of a molecule or particle and is defined in a mathematically rigorous manner in both classical and statistical thermodynamics. The goal of this research is to use simulations and experiments to understand how particle size and composition affect the particle chemical potential of attractive nanoparticle-polymer mixtures.
The expanded ensemble Monte Carlo (EEMC) simulation method for the calculation of the particle chemical potential for a nanocolloid in a freely adsorbing polymer solution is extended to concentrated polymer mixtures. The dependence of the particle chemical potential and polymer adsorption on the polymer concentration and particle diameter are presented. The perturbed Lennard-Jones chain (PLJC) equation of state (EOS) for polymer chains1 is adapted to calculate the particle chemical potential of nanocolloid-polymer mixtures. The adapted PLJC equation is able to predict the EEMC simulation results of the particle chemical potential by introducing an additional parameter that reduces the effects of polymer adsorption and the effective size of the colloidal particle.
Osmotic pressure measurements are used to calculate the chemical potential of nanocolloidal silica in an aqueous poly(ethylene oxide) (PEO) solution at different silica and PEO concentrations. The experimental data was compared with results calculated from Expanded Ensemble Monte Carlo (EEMC) simulations. The results agree qualitatively with the experimentally observed chemical potential trends and illustrate the experimentally-observed dependence of the chemical potential on the composition. Furthermore, as is the case with the EEMC simulations, polymer adsorption was found to play the most significant role in determining the chemical potential trends.
The simulation and experimental results illustrate the relative importance of the particles size and composition as well as the polymer concentration on the particle chemical potential. Furthermore, a method for using osmometry to measure chemical potential of nanoparticles in a nanocolloid-mixture is presented that could be combined with simulation and theoretical efforts to develop accurate equations of state and phase behavior predictions. Finally, an equation of state originally developed for polymer liquid-liquid equilibria (LLE) was demonstrated to be effective in predicting nanoparticle chemical potential behavior observed in the EEMC simulations of particle-polymer mixtures.
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Quant, Carlos A. "Colloidal chemical potential in attractive nanoparticle-polymer mixtures simulation and membrane osmometry /." Available online, Georgia Institute of Technology, 2004, 2004. http://etd.gatech.edu/theses/available/etd-08162004-112543/.
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Marla, Krishna Tej. "Molecular thermodynamics of nanoscale colloid-polymer mixures: chemical potentials and interaction forces." Available online, Georgia Institute of Technology, 2004, 2004. http://etd.gatech.edu/theses/available/etd-08102004-105655/.
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Thesis (Ph. D.)--Chemical Engineering, Georgia Institute of Technology, 2006.Dr. J. Carson Meredith, Committee Chair ; Dr. Charles A. Eckert, Committee Member ; Dr. Clifford L. Henderson, Committee Member ; Dr. Rigoberto Hernandez, Committee Member ; Dr. Peter J. Ludovice, Committee Member. Vita. Includes bibliographical references.
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Zhang, Xiaomin. "Synthesis and Physical Properties of Environmentally Responsive Polymer Gels." Thesis, University of North Texas, 1996. https://digital.library.unt.edu/ark:/67531/metadc277945/.
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Polymer gels undergo the volume phase transition in response to an infinitesimal environmental change. This remarkable phenomenon results in many potential applications of polymer gels. This dissertation systematically investigates the chemical and physical properties of polymer gels. It is found that infrared radiation laser not only induces a volume phase transition in N-isopropylacrylamide (NIPA) gel, but also causes the gel to bend toward the laser beam. The transmission of visible laser light through a NIPA gel can also be controlled by adjusting the infrared laser power. A new class of environmentally responsive materials based on spatial modulation of the chemical nature of gels has been proposed and demonstrated. Three simple applications based on the modulated gels are presented: a bi-gel strip, a shape memory gel, and a gel hand. The bending of bi-gels has been studied as a function of temperature, acetone aqueous solution, and salt solution. As the polymer network concentration increases, the behavior of shear modulus of acrylamide (PAAM) gels deviates significantlyfromthe classical theory. The ionic NIPA gels undergo two sequential volume phase transitions: one occurs in dilute NaCl solution, the other occurs in concentrated NaCl solution. An interpenetrating polymer network (IPN) of PAAM--NIPA has also been synthesized using free radical polymerization. It is found that the IPN gels preserve the essential properties of individual components. The volume phase transition of the IPN gels can be triggered by multiple external stimuli including temperature, acetone concentration, and salt concentration.
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Bagoury, Mohamed al. "Synthesis of aqueous polymer colloids based on saccharide monomers and alkyl acrylates through emulsion polymerization." [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=974074527.
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Brindley, Anne. "The preparation and characterization of model polymer colloids for potential site-specific drug delivery systems." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335470.
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Wang, Changjie. "Polymer Gels: Kinetics, Dynamics Studies and Their Applications as Biomaterials." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc4379/.
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The polymer gels especially hydrogels have a very special structure and useful features such as unusual volume phase transition, compatibility with biological systems, and sensitivity to environmental stimuli (temperature, pH value, electric field, light and more), which lead to many potential applications in physical and biochemical fields. This research includes: (1) the theoretical and experimental studies of polymer gels on swelling kinetics, spinodal decomposition, and solution convection in gel matrix; (2) applications of polymer gels in wound dressing, tissue-simulating optical phantom and gel display. The kinetics of gel swelling has been theoretically analyzed by considering coupled motions of both solvent and polymer network. Analytical solutions of the solvent and the network movement are derived from collective diffusion equations for a long cylindrical and a large disk gel. Kinetics of spinodal decomposition of N-isopropylacrylamide (NIPA) polymer gel is investigated using turbidity and ultrasonic techniques. By probing movement of domains, a possible time-dependent gel structure in the spinodal decomposition region is presented. Theoretical studies of solution convection in gel matrix have been done and more analysis on dimensionless parameters is provided. To enhance the drug uptake and release capacity of silicone rubber (SR), NIPA hydrogel particles have been incorporated into a SR membrane. This SR/NIPA composite gel has promising attributes for wound dressing and other uses. Tissue-simulating optical phantom has been synthesized and studied using NIPA solution trapped inside a hydrogel. Polymer gels with engineered surface patterns were implemented. NIPA gel deposited on the surface of an acrylamide gel can be used as responsive gel display. A dynamically measurement technique of local shear modulus and swelling ratio of gel is presented based on an engineered periodic surface pattern as square array.
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Pillai, Karthikeyan Chyan Oliver Ming-Ren. "FTIR-ATR characterization of hydrogel, polymer films, protein immobilization and benzotriazole adsorption on copper surface." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-5132.
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Hendrickson, Grant R. "Harnessing microgel softness for biointerfacing." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50252.
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Hydrogel materials have become a heavily studied as materials for interfacing with biology both for laboratory investigations and the development of devices for biomedical applications. These polymers are water swellable and can be made responsive to many different stimuli by choice of monomers, co-monomers, and cross-linkers or functionalization with pendent ligands, substrates, or charged groups. The high water content, low moduli and potential responsively of these polymers make good candidates for biomaterials. A specific type of hydrogel called a microgel or a hydrogel micro/nanoparticle has similar properties to bulk hydrogel materials. Many of the interesting results and utility of the microgels in bioapplications are due to their inherent softness of the material. Here, the softness, flexibility, and conformability of these water swollen particles is used to create an interesting sensor platform, studied in the context of a microgel passing through a pore, and used as an emulsifier to create a drug delivery platform. The unifying theme of this dissertation is the softness of microgels which is critical for all of these experiments. However, the study of individual microgel softness is challenging and complex, since the softness is composed of two different components. The first is that the microgel is a swollen polymer which can be deswollen by an external stimuli or force. The second is that the microgel is a volume conserving elastic colloid which can deform without deswelling under the certain conditions. Throughout, this dissertation will discuss the ramifications of the complex softness of microgels in each experimental result and potential application.
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Wang, Sheng. "Phosphorus-Containing Polymers, Their Blends, and Hybrid Nanocomposites with Poly(Hydroxy Ether), Metal Chlorides, and Silica Colloids." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/26789.
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Phosphorus-containing high performance polymers have been extensively studied during the last 10 years. These materials are of interest for a variety of optical and fire resistant properties, as well as for their ability to complex with the inorganic salts. This dissertation has focused on the nature of the phosphonyl group interactions with hydroxyl containing polymers, such as the poly(hydroxy ether)s. These may be considered linear models of epoxy resins and are also closely related to dimethacrylate (vinyl ester) matrix resins that are important for composite systems. It has been shown that bisphenol A poly(arylene ether phosphine oxide/sulfone) homo- or statistical copolymers are miscible with a bisphenol A-epichlorohydrin based poly(hydroxy ethers) (PHE), as shown by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), infrared spectroscopy and , solid state cross polarization-magic angle spinning nuclear magnetic resonance (CP-MAS). These measurements illustrate the strong hydrogen bonding between the phosphonyl groups of the copolymers and the pendent hydroxyl groups of the PHE as the miscibility inducing mechanism. Complete miscibility at all blend compositions was achieved with as little as 20 mole% of phosphine oxide units in the poly(arylene ether) copolymer. Replacement of the bisphenol A moiety by other diphenols, such as hydroquinone, hexafluorobisphenol A and biphenol did not significantly affect blend miscibilities. Miscible polymer blends with PHE were also made by blending poly(arylene thioether phosphine oxide), and fully cyclized phosphine oxide containing polyimides based on (prepared from 2,2'-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and bis(m-aminophenyl) methyl phosphine oxide (DAMPO)) or bis(m-aminophenyl) phenyl phosphine oxide).
Additional research has focused on the influence of these materials on the property characteristics of vinyl ester matrix resins and has shown that the concentration of phosphonyl groups controls the homogeneity of both oligomers and the resulting networks. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fracture toughness measurements further confirmed the qualitative observations.
Metal salts, such as CoCl2 and CuCl2 had earlier been demonstrated to form complexes/nanocomposites with phosphorus-containing poly(arylene ethers). It has been possible to prepare transparent films with 100 mol% of metal chlorides, based upon the phosphonyl groups. The films are transparent, unlike the opaque polysulfone control systems. FTIR results suggested the formation of inorganic salt and polymer complexes at low concentrations. TEM showed homogeneous morphology at low concentrations and excellent dispersion even at high mole % of salts. Cobalt materials reinforce the basic poly(arylene ether)s to provide higher modulus values and influence positively the char yield generated after TGA experiments in air. The cobalt salt/BPADA-DAMPO polyimide composites also yield transparent films, implying very small dimensions.
Silica-polymer nanocomposites were also produced by mixing commercial silica colloid/N,N-dimethylacetamide (DMAc) fine dispersions (~ 12 nm) with bisphenol A poly(arylene ether phenyl phosphine oxide). The dry films produced by solution casting are transparent and silica colloids are evenly dispersed (~ 12 nm) into the polymer matrix as shown by TEM. These nanocomposites increased char yield compared with the polymer control, suggesting their fire retardant character. In comparison, the silica/polysulfone hybrid films prepared by the same methods were opaque and the char yield was not improved. This different phase behavior has been explained to be due to the hydrogen bonding between phosphonyl groups and silanol hydroxyl groups on the surface of the nanosilica.Ph. D.
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Zhou, Jun. "Stimuli-responsive microgels for self-assembled crystalline structures and controlled drug release." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc11001/.
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Tissue response to PNIPAM and HPC nanoparticles has been studied by implantation method. The results suggest that both PNIAPM and HPC nanoparticles possess good biocompatibility and they may serve as a good carrier for the applications of controlled delivery. Rheological properties of dispersions of IPN microgels composed of PNIPAM and PAAc have been studied. It is found that the IPN microgel dispersion can undergo a sol-gel transition at temperature above 33°C. In vivo drug release experiments suggest that the gelation procedure creates a diffusion barrier and thus leads to slow release. An emulsion method has been used to grow columnar crystals by mixing PNIPAM microgel dispersions with organic solvents. Effect of both temperature and microgel concentration on formation of columnar crystals has been studied. PNIPAM-co-NMA microgels have been used for the fabrication of crystalline hydrogel films by self-crosslinking microgels. The hydrogel film exhibits an iridescent. The thermally responsive properties and mechanical properties of this film have been studied. Melting temperature (Tm) of colloidal crystals self-assembled with PNIPAM-co-AAc microgels has been investigated as a function of pH, salt concentration and microgel concentration. It is revealed that Tm increases as pH value increases; Tm decreases with increase of salt concentration; Tm increases as microgel concentration increases. Phase behavior of PNIPAM-co-HEAc microgel dispersions has been investigated. It is observed that these microgel dispersions exhibit liquid, crystal, and glass phase. As microgel size increases, crystal phase shifts to low concentration range. As temperature increases, crystal phase shifts to high concentration ranges. These colloidal crystals can be stabilized by NaOH-induced gelation. Effect of NaOH concentration on formation of physical gelation has been investigated.