Thèses sur le sujet « Amphiphilic graft copolymer »
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Lovell, Nathan Gary. « Control of size and charge selectivity in amphiphilic graft copolymer nanofiltration membranes ». Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62607.
Texte intégralThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 99-106).
The throughput and efficiency of membrane separations make polymer filtration membranes an important resource for the pharmaceutical, food and wastewater treatment industries. Nanofiltration (NF) membranes fill an important niche between nonporous reverse osmosis membranes, which have comprehensive solute rejection and low solvent permeability, and porous sieving ultrafiltration membranes. However, challenges in NF membrane design remain outstanding. At the effective pore size of NF membranes (~0.5 nm-2 nm), both electrostatic and steric factors determine membrane selectivity. Most NF membranes are charged under a wide range of environmental conditions and thus preferentially exclude charged solutes. This charge selectivity precludes separation of molecules based solely on size. An additional limitation of NF membranes is the tendency to foul by adsorption of feed components. The purpose of this thesis is to demonstrate control of membrane selectivity in fouling resistant membranes via manipulation of the chemistry of a specific copolymer system, polyacrylonitrile (PAN)-based poly(ethylene oxide) (PEO) graft polymers. Previous work with amphiphilic graft copolymers as membrane materials has included PANg- PEO with an average graft length of 9 (PAN-g-PEO9). PAN-g-PEO9 was shown to have excellent fouling resistance as an antifouling additive in porous ultrafiltration membranes and as a dense selective layer coated onto a support base membrane-a thin-film composite (TFC) NF membrane. The comb morphology of the polymer imposes high interfacial area on the microphase-separated domains, resulting in a bicontinuous structure consisting of a glassy PAN matrix interpenetrated by PEO-filled "nanochannels" that can act as vias for water and small solutes (with a size cutoff of ~0.8 nm). It also presents a PEO brush on the comb surface which acts as a steric barrier to resist irreversible fouling of the membranes. The understanding from previous work on PEO comb NF membranes is that the pore size is determined by the nanochannel's size, i.e. the PEO domain size. Because the graft characteristics (spacing and length) of comb copolymers determine the domain size, it was expected that varying the graft length would allow broad, precise control of the size cutoff of the TFC membranes, a concept demonstrated previously with amphiphilic graft copolymer NF membranes of poly(vinylidene fluoride)-graft-poly(oxyethylene methacrylate) (PVDF-g-POEM). The first aim of this thesis was to tailor the retention properties of PAN-g-PEO TFC NF membranes by modifying the chemistry to tune the electrostatic and steric properties sufficiently to enable complex separations, particularly of solutes with high fouling potential. Comb copolymers incorporating ~40 weight % PEO with side chains varying from 5-40 EO units were synthesized by free radical methods and compared as selective-layer coatings on PAN UF membranes. 3 Membranes incorporating combs with 9 EO units or more were shown to resist irreversible fouling when challenged by a model protein feed solution (bovine serum albumin) for 24 hours. Fouling resistance was found to be compromised, however, upon exposure to acid (pH 2) solution, used to simulate chemical cleaning procedures in industry. Thickness-normalized permeabilities of these PAN-g-PEOn NF membranes exceeded those of commercially available NF membranes by approximately an order of magnitude. A systematic effect of side chain length on permeability was seen when varying temperature, ionic strength, and pressure. Contrary to expectations, the membrane size cutoff (~0.8 nm) for charged rigid molecular probes in deionized water was independent of the comb side chain length. This new finding can be explained by modeling the hydrophilic domains as opposing swollen polymer brushes of uniform density acting as a physical gel. The gel mesh size (distance between chains) is independent of side chain length, and controls the size cutoff in good solvent conditions matching those in which the membrane was equilibrated during fabrication. In poorer solvent conditions, a decrease in the brush height, progressing to complete collapse of the PEO gel, can be expected to create differentiation based on domain size (i.e. side chain length). This is consistent with the finding that retentions of dyes increased with decreasing side chain length in saline solution, as salt is known to reduce PEO-water miscibility. Fluorescently labeled peptides germane to proteomics research were filtered and both chromatographic and size-selective membrane behavior was observed-the first demonstration of size-based nanofiltration of peptides. Based on this finding, two different peptides of molecular weights 1.3kDa and 1.5kDa were fractionated to achieve a six-fold increase in the concentration of the larger peptide relative to the smaller peptide in two filtration steps. The electrostatic selectivity of the PEO comb membranes could also be varied. Terpolymers consisting of PAN-g-PEO with 1-2% charged sulfopropyl acrylate (SPA) or 5% N,Ndimethyl- N-(2-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium betaine (SPE) were synthesized and coated onto PAN base membrane. The divalent salt (Na2SO4) retention of the resulting TFC membranes increased from ~20% for the PAN-g-PEO copolymer to ~45% and 82% for the SPE and SPA terpolymers, respectively. Retention of monovalent NaCl was substantially lower, characteristic of commercial NF membranes. The charged comb membranes did not completely resist fouling by a 1 g/L BSA solution, losing 2% of the initial flux after 24 h exposure. Forming a trilayer TFC, with a layer of PAN-g-PEO coated over a charged terpolymer, reduced membrane fouling compared to the charged layer alone. In summary, the goal of this study was to demonstrate control of membrane selectivity in fouling-resistant PAN-g-PEO NF membranes. An important finding was that the PEO gel created in the hydrophilic domains leads to similar size cutoffs over a wide range of side chain length. To access the desired spectrum of size cutoffs, the quality of solvent for the swollen PEO brush must be reduced. In spite of these limitations, the membrane was shown to have useful fractionating properties as demonstrated with labeled peptides of varying molecular weight. The retention of salts was enhanced by incorporating small amounts of charged monomer into the comb backbone, but at the expense of fouling resistance.
by Nathan Gary Lovell.
Ph.D.
Kuhlman, William A. « Presentation and accessibility of surface bound ligands on amphiphilic graft copolymer films ». Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39549.
Texte intégralIncludes bibliographical references.
Amphiphilic comb-type graft copolymers comprising a poly(methyl methacrylate) (PMMA) backbone and short, polyethylene oxide (PEO) side chains, PMMA-g-PEO, are proposed to self-organize at the polymer/water interface, resulting in quasi-2D confinement of the backbone at the immediate surface. The branched architecture and amphiphilic chemistry of these polymers results in a dense PEO brush that resists cell adhesion. To facilitate specific cell-surface interactions, small biological molecules such as adhesion peptides can be selectively tethered to PEO chain ends. Quasi-2D confinement of the polymer backbone results in clustering of tethered epitopes on a length scale dictated by the backbone. The present work investigates two aspects of this polymer architecture on organization of tethered ligands: nanometer length-scale clustering through backbone 2D confinement, and tether length effects on the availability of tethered peptides for cell adhesion.
(cont.) To directly probe 2D confined polymer conformations, combs at the film/water interface were labeled with gold nanoparticles and observed by transmission electron microscopy. A 2D radius of gyration (Rg) was calculated by reconstructing nanoparticle-decorated chain trajectories, and compared with Monte Carlo simulations of a 2D melt of similarly broad length distribution. The 2D Rg calculated from observed conformations scaled with the number of backbone segments (N) as Rg - N.69-0.02 Monte Carlo simulations yielded a scaling exponent v = 0.67 + 0.03, suggesting that the deviation from classical 2D melt behavior (v= 0.5) arose from polydispersity. Tether length effects on cell adhesion to comb copolymer films functionalized with the adhesion peptide PHSRNGGGK(GGC)GGRGDSPY were further investigated by observing cell attachment and spreading on combs with long (22 EO unit) and short (10 EO unit) tethers. Lofiger tethers increased the rate of spreading and reduced the time required to form focal adhesions. Fluorescence resonance energy transfer (FRET) measurements suggest that the added mobility afforded by longer tethers allowed cells to reorganize tethered peptides.
(cont.) In addition, adhesion peptides were selectively coupled to short or long PEO tethers within a bimodal brush. Short peptide tethers in a bed of long inert chains did not promote cell attachment. Long peptide tethers with short inert chains resulted in cell attachment comparable to a monomodal brush of long chains. These findings may be of value in designing protein-resistant bioactive surfaces, where nanometer length-scale organization of ligands plays an important role in cell-surface interactions.
by William A. Kuhlman.
Ph.D.
Lapree-Delestre, Christine. « Synthèse et étude physico-chimique d'alginates substitues par des polyoxyalkylenes en vue d'applications d'intérêt biologique ». Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL156N.
Texte intégralLauber, Lionel. « Control of the rheological properties of hydrogels made by self-assocation of amphiphilic copolymers, blocks and grafts, anionics or cationics ». Thesis, Le Mans, 2016. http://www.theses.fr/2016LEMA1010/document.
Texte intégralThe aim of this work was to control the rheological properties of aqueous solutions of amphiphilic copolymers. In water, these copolymers self-assemble and part of their properties can be controlled by their dynamic of exchange. As previously reported, the exchange dynamics can be controlled by the pH and the acrylic acid (AA) content for BAB triblock copolymers (THx) consisting of a poly(acrylic acid) (PAA) A block and two statistical B blocks (MHx) of n-butyl acryle (nBA) and AA.First, the study of the self-association of B blocks (MHx) alone showed a strong relationship between their aggregation and the one of BA diblocks (DHx). This aggregation was mainly controlled by the amount of charges within the B blocks.Then, mixtures of BAB triblocks (THx) with different contents of AA units, x, formed hybrid networks the rheological properties of which were controlled by formulation rather than chemistry.Similar rheological properties were obtained using graft copolymers consisting of a PAA hydrophilic backbone and B grafts. Their rheological properties were mainly controlled by the chemical structure of the B grafts and by the grafting density. Such graft copolymers should be easier to produce at an industrial scale than triblock copolymers.To finish, the strategy consisting of incorporating hydrophilic units inside the hydrophobic blocks of amphiphilic copolymers to control their exchange dynamics was successfully applied to copolymers made of dimethylaminoethyl methacraylate and n-butyl methacrylate. Their rheological properties were controlled by the pH on a different pH-range than the AA based polymers, and, to some extent, by the temperature
Zhang, Dapeng. « Synthèse de polyuréthanes par polymérisation par ouverture de cycle anionique et auto-assemblage de copolymères amphiphiles à base de polyuréthane ». Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEC007.
Texte intégral1.Controlled anionic ring opening polymerization of 5-membered cyclic carbamates to polyurethanes. 2.Synthesis and self-assembly of polyurethane-based amphiphilic linear diblock copolymers. 3.Synthesis and self-assembly of polyurethane-based amphiphilic graft copolymers
Bayley, Gareth Michael. « Novel electrospun fibres of amphiphilic organic-inorganic graft copolymers of poly(acrylonitrile)-graftpoly( dimethylsiloxane) for silicone composite reinforcement ». Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17875.
Texte intégralENGLISH ABSTRACT: Novel silicone nanocomposites were prepared using poly(acrylonitrile) (PAN) based reinforcing fibres as well as multi-walled carbon nanotubes (MWCNTs). Compatibility of the fibre fillers with the silicone matrix required the synthesis of novel amphiphilic, organic–inorganic graft copolymers of PAN and poly(dimethylsiloxane) (PAN-g-PDMS). These fibre precursor materials were synthesised via the “grafting through” technique using conventional free radical copolymerisation. The PDMS macromonomer content in the feed was varied from 5 wt% to 25 wt% and the molecular weights of the macromonomer were 1000 g.mol-1 and 5000 g.mol-1. The solvent medium of the precipitation reaction was optimised at a volume ratio of 98% benzene to 2% dimethylformamide (DMF). Successful incorporation of PDMS yielded graft copolymer blend materials of PAN-g-PDMS, blended with PAN homopolymer and unreacted PDMS macromonomer. A gradient elution profile was developed to track the successful removal of the PDMS macromonomer via hexane extraction. The gradient profile showed that as the PDMS content in the feed increased, the number of graft molecules in the blend increased relative to the number of PAN homopolymer molecules. The crystallisability of the PAN segments was shown to decrease as the PDMS content increased. The synthesised polymer was used as precursor material for the electrospinning of fibre fillers. The electrospinning of the precursor material was successfully achieved using 100% DMF as electrospinning solution medium. The amphiphilic nature of the precursor material in DMF resulted in self-assembled aggregate structures in the electrospinning solution. An increasing PDMS content was shown to affect the aggregation of the precursor material, and resulted in an increase in the solution viscosity. The “gel-like” solutions limited the achievable fibre morphological control when altering conventional electrospinning parameters such as voltage, tip-to-collector distance, and solution concentrations. The rapid evaporation and stretching of the solution during electrospinning, combined with the phase segregated amphiphilic molecules in solution and the crystallisation of the PAN segments resulted in (non-equilibrium morphology) fully porous fibres. The crystallinity was shown to decrease after electrospinning of the fibre precursor materials. Successful incorporation of surface oxidised MWCNTs into the electrospun fibres was achieved. The content of nanotubes was varied from 2 wt% to 32 wt%. The MWCNTs reduced the mean fibre diameters by acting as cross-linkers between the PAN segments and increasing the solution conductivity. The nanotubes dispersed well throughout the porous structure of the fibres and aligned in the direction of the fibre axis. Fabrication of silicone composites containing nonwoven and aligned fibre mats (with 8 wt% MWCNTs in the fibres, and without) was successfully achieved. The compatibilisation of the PDMS surface segregated domains allowed excellent dispersion and interaction of the PAN based fibre fillers with the silicone matrix. Mechanical analysis showed improved properties as the PDMS content in the fibre increased. The highest PDMS content fibres did, however, exhibit decreased properties. This was ascribed to increased PDMS (soft and weak) content, decreased crystallinity and increased fibre diameter (lower interfacial area). Dramatic improvements in strength, stiffness, strain and toughness were achieved. The most significant result was an increase in strain of 470%. The mechanical results correlated with results of SEM analysis of the fracture surfaces. The dramatic improvements in properties were a result of the fibre strength and ductility, as well as the mechanism of composite failure.
AFRIKAANSE OPSOMMING: Nuwe silikonnanosamestellings is berei deur gebruik te maak van poli(akrilonitriel) (PAN) gebaseerde versterkende vesels wat multi-ommuurde koolstof nanobuisies bevat het. Versoenbaarheid van die vesels met die silikonmatriks het die sintese van nuwe amfifiliese, organies–anorganiese ent-kopolimere van PAN en poli(dimetielsiloksaan) (PAN-g-PDMS) benodig. Die vesel voorlopermateriaal is deur middel van ‘n “ent-deur” vryeradikaalkopolimerisasie gesintetiseer. Die inhoud van die PDMS makromonomeer in die reaksie het gewissel vanaf 5% tot 25%. Die gebruik van twee verskillende molekulêre massas makromonomere is bestudeer (1000 en 5000 g.mol-1). Die optimale oplosmiddelmengsel vir die neerslagreaksie was 'n volume verhouding van 98% benseen tot 2% dimetielformamied (DMF). Suksesvolle insluiting van PDMS het versnitmateriale van PAN-g-PDMS kopolimere gemeng met PAN homopolimere en ongereageerde PDMS makromonomere gelewer. 'n Gradiënteluering- chromatografiese profiel is ontwikkel om die suksesvolle verwydering van die PDMS makromonomere via heksaanekstraksie te bepaal. Die gradiëntprofiel het aangetoon dat indien die PDMS inhoud in die reagense verhoog is, die aantal entmolekules relatief tot PAN homopolimeermolekules ook verhoog het. 'n Toename in PDMS inhoud het egter 'n afname in kristallisasie van die PAN segmente tot gevolg gehad. Die gesintetiseerde polimeer is gebruik as die beginmateriaal vir die elektrospin van veselvullers. Die elektrospin van die beginmateriaal was suksesvol wanneer 100% DMF as elektrospinoplosmiddel gebruik is. Die amfifiliese aard van die beginmateriaal in DMF lei tot outokonstruksie van aggregaatstrukture in die elektrospinoplossing. Toenemende PDMS inhoud beïnvloed die outokonstruksie van die molekules in oplossing en het gelei tot 'n toename in die oplossings se viskositeit. Die "gelagtige" oplossings beperk die haalbare vesel se morfologiese beheerbaarheid wanneer konvensionele elektrospin parameters soos elektriese spanning, punt-tot-versamelaar afstand, en oplossingkonsentrasies gewysig word. Die vinnige verdamping en strek van die oplossing tydens elektrospin, gekombineer met die fase-geskeide amfifiliese molekules in oplossing en die kristallisasie van die PAN segmente, het gelei tot (nie-ewewig morfologie) volledige poreuse vesels. Die kristalliniteit van die veselbeginmaterial het afgeneem nadat elektrospin toegepas is. Die insluiting van die oppervlak-geoksideerde multi-ommuurde koolstof nanobuisies in die elektrogespinde vesels was suksesvol. Die inhoud van die nanobuisies het gewissel van 2 wt% tot 32 wt%. Die MWCNTs het die gemiddelde veseldeursnit verminder deur op te tree as kruisbinders tussen die PAN segmente van die molekules. Die nanobuisies was goed versprei deur die poreuse struktuur van die vesels en dit was gerig in die rigting van die vesel-as. Bereiding van die silikonsamestellings bestaande uit nie-geweefde en gerigte veseloppervlakke (met en sonder 8 wt% multi-ommuurde koolstof nanobuisies in die vesel) was suksesvol. Die versoenbaarheid tussen die oppervlak van die PDMS-geskeide gebiede en die silikonmatriks laat uitstekende verspreiding en interaksie van die PAN-gebaseerde veselvullers met die silikonmatriks toe. Meganiese analise het aangetoon dat die fisiese eienskappe verbeter het namate die PDMS inhoud in die vesel vermeerder het. Die vesels met die hoogste PDMS inhoud het egter verswakte eienskappe getoon. Dit is toegeskryf aan ‘n verhoogde PDMS inhoud (sag en swak), ‘n afname in kristalliniteit en ‘n verhoogde veseldeursnit (laer grensoppervlakke). Dramatiese verbeterings in sterkte, styfheid, verlengbaarheid, vervorming en taaiheid is bereik. Die mees betekenisvolle gevolg was 'n toename in die verrekking van 470%. Die meganiese resultate is gekorreleer met SEM ontleding van die brekingsoppervlakke. Die veselkrag en vervormbaarheid, sowel as die meganisme van die splyting van die samestellings, het tot die dramatiese verbeterings in die meganiese eienskappe gelei.
Breitenkamp, Rebecca Boudreaux. « Oligopeptide-functionalized Graft Copolymers : Synthesis and Applications in Nucleic Acid Delivery ». Amherst, Mass. : University of Massachusetts Amherst, 2009. http://scholarworks.umass.edu/open_access_dissertations/5/.
Texte intégralMeltz, Freda-Jean. « Amphiphilic electrospun fibres of poly(methacrylic acid)-graft-poly(dimethylsiloxane) copolymers as a means to controlling electrospun fibre morphology and obtaining nanofibre hydrogels ». Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86620.
Texte intégralENGLISH ABSTRACT: Novel poly(methacrylic acid)-graft-poly(dimethylsiloxane) copolymers were synthesised by conventional free radical reactions using a poly(dimethylsiloxane) macromonomer. The polymers were electrospun to investigate how the fibre morphology can be modified by manipulating the electrospinning solution parameters, and to determine the possibility of using the polymers as new materials for the production of polymer nanofibre hydrogels. The electrospinning solution parameters were varied by electrospinning the highly amphiphilic copolymers in solvents with variable solvent qualities. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FE–SEM) was used to investigate the fibre morphology. Internal morphology was studied using a freeze fracture technique prior to FE-SEM imaging. It is revealed that the polymers in this study does not form any fine structure or pores even when self-assembled structures are present in the solution. Attempts were made to visualise any self-assembled structures of films produced from dilute solutions using TEM. Further studies included investigating the fibres properties, primarily with regards to their rate and extent of moisture and water uptake. The fibres showed hydrogel behaviour and the PDMS content were found to have an impact on the hydrogel stability. Post electrospinning crosslinking of the nanofibres was also explored.
AFRIKAANSE OPSOMMING: Unieke ent-kopolimere wat bestaan uit poli(metielakrielsuur) (PMAS) en poli(dimetielsiloksaan) (PDMS) is gesintetiseer deur middel van 'n “ent-deur” vryeradikaalkopolimerisasie. 'n PDMS makromonomeer is vir hierdie doel gebruik. Die polimere is geëlektrospin om vesels te vorm. Die doel was om die invloed van verkillende strukture in oplossing op die veselmorfologie te bepaal. Die moontlikheid om hierdie nanovesels as gels te gebruik is ook ondersoek. Die amfifiliese kopolimere is geëlektrospin uit die oplossing waarin dit wisselende oplosbaarheid toon. Skandeer elektron mikroskopie (SEM) is gebruik om die morfologie te ondersoek. Die interne morfologie van die vesels is ondersoek deur die vesels te vries en in die gevriesde toestand te breek. Die studie het getoon dat geen strukture op, of binne, die vesels vorm nie, selfs al moes daar assosiasie tussen segmente van die polimere gewees het. Hierdie tipe assosiasies sou strukture in die oplossing tot gevolg gehad het. 'n Poging is aangewend om die strukture in oplossing te visualiseer deur transmissie elektron mikroskopie (TEM) van dun films te ondersoek. Films is vanaf verdunde oplossings gevorm. Ander studies het ingesluit om die eienskappe van die vesels te ondersoek, met die fokus op hoeveel en hoe vinnig die vesels waterdamp en water kon absorbeer. Die vesels het soos 'n gel reageer. Hierdie gedrag is beïnvloed deur die hoeveelheid PDMS wat 'n definitiewe invloed op die stabiliteit van die gel gehad het. Kruisverbindings van die vesels, nadat dit geëlektrospin is, is ook ondersoek.
Delorme, Victor. « Nouveaux systèmes copolymères amphiphiles biodégradables pour la délivrance de principes actifs anticancéreux ». Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS140.
Texte intégralThis work presents the synthesis of biocompatible and biodegradable amphiphilic copolymers for the formation of anticancer drug delivery systems. These copolymers consist of a poly-(ε-caprolactone) (PCL) chain, a biocompatible and biodegradable hydrophobic polyester, on which hydrophilic oligomers of dextrane or chitosane are grafted. These new copolymer structures are called “reverse” structures, the “classic” ones being made of a polysaccharide chain with PCL grafts. The PCL chain was propargylated via an anionic method developed by our team, while azide functions were grafted on oligosaccharides at a chain end of dextrane, but along the chain in chitosan, thanks to its amine functions. Copolymers were obtained by CuAAC click coupling between the activated PCL and oligosaccharides. In the case of chitosan, the amines of the chain allowed the coupling of mannose squarate, a cancer cell targeting agent, as well as a functionalization in the form of thiols which allow coupling by thiol-yne reaction on propargylated PCL. These copolymers form nano objects in aqueous media which, in the case of the PCL-g-dextrane structure, are forming micelles that encapsulate doxorubicin, which is further released in a pH- dependent way. Biological studies have shown that these charged micelles are toxic to cancer cells and not to healthy cells and are preferentially internalized by cancer cells. These results demonstrate a high degree of selectivity of action against tumor cells
BIANCHI, ALBERTO. « Living radical polymerization for the preparation of innovative macromolecular architectures ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/41784.
Texte intégralYang, Kai-Shiang, et 楊凱翔. « Synthesis and Characterization of Amphiphilic Graft Copolymer ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/2meq68.
Texte intégral國立臺灣科技大學
化學工程系
94
In this study, amphiphilic polymers comprising both PEG and distearin (or stearyl alcohol) side chains were synthesized and characterized. Grafting efficiency and relative average molecular weight were determined by 1H-NMR and GPC, respectively. Amphiphilic graft copolymer is capable of forming micelles in the aqueous solutions with different pH values. Characteristic properties of polymeric micelles were analyzed by fluorescence spectroscopy and dynamic light scattering (DLS). The colloidal system has lower CAC values (1.87~24.4 mg/l), higher partitioning coefficients (9588~8272), larger particle sizes (100~150 nm), higher rotational correlation time (2.46~3.09 × 10-10 s) and lower hyperfine coupling constant (15.42~15.48 G) in pH 4 buffer. On the other hand, these copolymers show opposite results in pH 7 buffer. For the copolymer-modified liposomes, the liposome complex shows good colloidal stability, as shown by the DLS data. Liposomes encapsulated by distearin side chains have higher encapsulation efficiency, higher crystallization temperature, lower fluorescence permeability and higher fluorescence intensity ratio (I3/I1). The copolymer with distearin side chains forms more compact and smaller micelles compared to the stearyl alcohol counterpart. These results indicate that the graft copolymers can effectively improve the colloidal stability of liposomes and are pH sensitive. These graft copolymers find potential application as the pH-sensitive drug delivery carrier.
Wu, Pei-Ling, et 巫佩玲. « Cisplatin-loaded amphiphilic graft copolymer micelles for drug delivery systems ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/16203838414930751312.
Texte intégral高雄醫學大學
醫藥暨應用化學研究所
101
In this study, we designed a novel comb-shaped amphiphilic copolymer, poly(ethylene glycol)-b-poly(ε-caprolactone)-g-poly (methacrylic acid) (MPCL-g-pMAA), which was synthesized by atom transfer radical polymerization (ATRP). We controlled the molar ratio of pMAA and MPCL to form three copolymers with different hydrophilic/hydrophobic characteristics. The MPCL-g-pMAA could self-assemble into micelles in aqueous solution with hydrophobic PCL in the center and hydrophilic PEG and MAA on the surface to increase circulation time in the blood. The carboxylic groups of pMAA were used to coordinate with an anticancer agent, Cisplatin, and the formed polymer-metal complexes could be used for cancer therapy. We used dynamic light scattering (DLS) and transmission electron microscope (TEM) to observe sizes and morphologies of micelles with and without Cisplatin. The drug loading efficiency and the hydrodynamic diameter increased with increasing amount of the carboxylic groups of MPCL-g-pMAA. The MPCL-g-pMAA with the least hydrophilic block length of pMAA showed the highest drug release amount as well as the highest cytotoxicity. The cellular internalization was visualized using a confocal laser scanning microscopy (CLSM).
Lin, Kuo-Ging, et 林國靖. « Development of Amphiphilic Graft Copolymer-Liposome Conjugates and Their Stability Characterization ». Thesis, 1999. http://ndltd.ncl.edu.tw/handle/16547402185640759033.
Texte intégral國立臺灣科技大學
化學工程系
87
In this study, a novel polymer modifier designed to improve the physical and biological stability of liposomes was proposed. A series of polymeric modifiers comprising monomeric units of stearyl methacrylate, acrylic acid, and PEG acrylate was synthesized using AIBN as initiator at 70 ℃. The compositions and molecular weights of these comb copolymers were determined by IR and 1H-NMR and GPC,respectively.The fluorimetric techniques were used to characterize the properties of the aqueous solutions of comb copolymer micelles. This method is based on the measurements of the ratio of intensities of the third and first vibrational bands, I3/I1, in the emission spectra of pyrene solubilized in a polymer solution as a function of micellar concentration. The strong perturbation of the vibronic band intensities was used as a probe to accurately determine the CMC of these comb copolymers. While stearyl methacrylate acts as an anchor by being dissolved in the phospholipid part of liposomes, the polymeric main chain further enhances the stability of liposomes by unlocalization of the PEG-grafted copolymer through liposomal surface area. PEG on the liposome surface exerts its aqueous repulsion effect on approaching macromolecules and/or cells and elevates the biological stability of the modified liposomes. In addition, the membrane structure of these polymer-coated liposomes, the dependence of liposome diameter versus time, and release behavior of water-insoluble and water-soluble model compounds were also investigated.
Chang, Kuo-Yung, et 張國勇. « Preparation of the amphiphilic Poly(ester) graft–Poly(γ–glutamic acid) copolymer and its application as an anticancer drug carrier ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/29493729896175789039.
Texte intégral國立清華大學
化學工程學系
98
The colorectal cancer is the third death reason of the cancer in Taiwan, and the second in the world. The greatest defects of the anticancer drug for chemotherapy are able to kill normal cells but also cause the damage of the normal tissues or organs at the same time. Furthermore, the cancer cells can resist anticancer drug by themselves or through gene mutation by chemotherapy, resulting in forming drug resistances and losing the effect of the drugs. The main goal of this research is to develop a novel method of polymerization using an anticancer drug as the initiator, which produces nano-scale micelles with two kinds of anticancer medicines to overcome above defects. These micelles will kill cancel cells effectively and improve healing efficiency. First, an anticancer drug (5’DFUR) is utilized directly to be an initiator in the polymerization, and ε-caprolactone or (lactide/glycolide) is polymerized to form the 5’DFUR-poly(ε-caprolactone) (5’DFUR-PCL) or 5’DFUR-poly (lactide-co-glycolide)(5’DFUR-PLGA) in this study. The 5’DFUR-PCL and 5’DFUR-PLGA are then grafted to Poly (glutamic acid) (γ-PGA) to form a comb-like amphiphilic copolymers respectively (5’DFUR-PCL-γ-PGA and 5’DFUR-PLGA-γ-PGA). The characteristics of the copolymers will be examined by FT-IR, NMR and GPC. Additionally, a second anticancer drug is coated on micelles of amphiphilic copolymers by self-assembly method in aqueous phase to from a micelle with two kinds of the anticancer medicines. The effects of drug delivery and cure of colorectal cancer in vitro will be investigated. We expect that this novel polymerization method is able to replace the present technique, which would decrease the steps of the preparation process and reduce the prime cost; on the other hand, the nano-micelles carriers are designed from the concept of the cocktail therapy, might provide a way to cure effectively the colorectal cancer.
Lee, Chih-Ta, et 李致達. « Preparation of Novel Amphiphilic Poly(L-lactide) -graft-Chondroitin Sulfate Copolymer and Its Application in Drug Delivery and Tissue Engineering ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/14757148673488367800.
Texte intégral國立清華大學
化學工程學系
94
In this investigation, new biodegradable brush-like amphiphilic copolymers were synthesized by ring opening polymerization. Poly(L-lactide) (PLLA) was grafted onto chondroitin sulfate (CS), which is one of the physiologically significant specific glycosaminoglycans (GAGs), using a tin octanoate [Sn(Oct)2] catalyst in DMSO. The hydroxyl groups of the chondroitin sulfate were used as initiating groups. These functional groups enable specific mucoadhesion or receptor recognition. The degree of substitution (DS), the degree of polymerization (DP) and the chondroitin sulfate content (from 1.1% to 15.4%) were analyzed by 1H-NMR. The characteristics of these grafted copolymers, including the structure, the thermal properties and biodegradability etc., were examined with respect to CS content. Meanwhile, the amphiphilic core (PLLA) - corona (CS) nanoparticles, with size smaller than 200 nm, was examined by dynamic light scattering (DLS). Zeta potential analysis exhibited the value in the range -18.3 to -49.4 mV. The morphologies of the nanoparticles were observed by field-emission scanning electron microscopy (FE-SEM). The nanoparticles with lower cytotoxicity were examined by MTT assay. Furthermore, the in vitro BSA release kinetics of those CSn-PLLA nanoparticles was also determined in this study. Novel polymeric amphiphilic copolymers were synthesized using chondroitin sulfate (CS) as a hydrophilic segment and poly(L-lactide) (PLLA) as a hydrophobic segment. Micelles of those copolymers were formed in an aqueous phase and were characterized by 1H NMR spectra, fluorescence techniques, dynamic light scattering (DLS), atomic force microscopy (AFM) and confocal microscopy. Their critical aggregation concentrations (CAC) are in the range of 0.0043 to 0.0091 mg/mL at 25oC. The partition equilibrium constants, Kv, of the pyrene probe in the aqueous solution were from 3.65×105 to 1.41×106 at 25 oC. The mean diameters of the micelles were below 200 nm, and their sizes were narrowly distributed. The AFM images revealed that the self-aggregates were spherical. Additionally, the CSn-PLLA micelles can efficiently transport within the cells via endocytosis as observed from confocal microscopy. In cartilage tissue engineering, the graft copolymer was blended with poly(L-lactide) (PLLA) to form biomimic porous scaffolds. Natural CS was introduced into the polyester matrix to promote the proliferation of cells. Three-dimensional sponge-like scaffolds were fabricated by a combination of salt leaching and solvent casting methods. The morphology of the scaffolds was observed with scanning electron microscopy (SEM) with average pore size between 50~250 μm and its porosity was high (>85%). Compression analysis indicated that the mechanical properties of the scaffold were adequate to support the proliferation of cells. The hydrophilicity increased with increasing the copolymer content in the blend, as determined by measuring the contact angle. H&E, Masson and Safranin-O staining showed that cells formed a chondro-tissue gradually. Histological results revealed that abundant cartilaginous matrices surrounded spherical chondrocytes in the center of the explants. Chondrocytes cultured in this ECM-like scaffold maintained a round morphology phenotype, characterized by a significant quantity of extracellular matrix of sulfated glycosaminoglycans and collagens. Additionally, phenotypic gene expression (RT-PCR) indicated that chondrocytes expressed transcripts that encoded type II collagen and aggrecan, and generated sulfated glycosaminoglycans.
Chiu, Jiun-Wei, et 邱俊瑋. « Synthesis and Characterization of Poly(ethylene glycol)-Containing Amphiphilic Graft Copolymer Used as Enzyme Immobilization Carrier and its Self-Assembled Behavior in Aqueous Phase ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/u3n65x.
Texte intégral國立臺灣科技大學
化學工程系
95
Amphiphilic copolymers comprising poly(acrylic acid) (PAAc) as the backbone and monomethoxy poly(ethylene glycol) (mPEG) as the grafts were synthesized and characterized. The functional group, grafting efficiency and relative average molecular weight were determined by FTIR, 1H-NMR and GPC, respectively. This copolymer as a carrier is capable of immobilizing chymotrypsin (ChT) in alkaline aqueous phase. GPC and SDS-PAGE were used to whether ChT was success fully attached on to the amphiphilic polymer carrier. Characteristic properties of polymer-protein conjugate system were analyzed by fluorescence spectroscopy, dynamic light scattering (DLS) and quartz crystal microbalance (QCM). The carrier system has lower CAC values (0.831~2.072 g/l), lower λmax (416~422 nm) of 2-AN spectrum, smaller particle sizes (only for P5-ChT (53.6 nm)) and higher frequency (only for P10-ChT (148.77 Hz)) in pH 4 buffer solutions. On the other hand, this carrier system show opposite results in pH 7.5 buffer solutions. In activity assay, residual activity increased with increasing the mPEG amounts and pH values. This carrier system has obviously high activity in pH 9 buffer solution.
Corrons, Xavier Castellvi. « Self-assembled microcapsules : understanding and controlling the release of payloads ». Doctoral thesis, 2022. http://hdl.handle.net/2158/1277190.
Texte intégralAlzahrany, Yahya. « Synthesis of Arborescent Amphiphilic Copolymers ». Thesis, 2013. http://hdl.handle.net/10012/7296.
Texte intégralCHEN, CHIEN-CHENG, et 陳建誠. « Thermostability of α- chymotrypsin modified by Poly(ethylene glycol)-Cotaining Amphiphilic Graft Copolymers ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/79794393424591699876.
Texte intégral國立臺灣科技大學
化學工程系
97
Amphiphilic copolymers comprising poly(acrylic acid) (PAAc) as the backbone and monomethoxy poly(ethylene glycol) (mPEG) as the grafts were synthesized and characterized. The copolymers were used for conjugation with different amounts of α - chymotrypsin immobilized enzyme system. In this study, it was intended to investigate the activity of enzyme after grafting toward high and low molecular weight substrates. N-Benzoyl-L-Tyrosine ethyl ether was used as a low molecular weight substrate whereas bovine serum albumin and Azocasein was used as a high molecular substrate. Residual activity increased with increasing the mPEG amount when a low molecular weight substrate was used. But enzyme's residual activity was reduced along with temperature increment. The cleavage rate of bovin serum albumin and Azocasein was reduced due to the excess amounts of mPEG that would induce steric effect, there by leading to slow cleavage rate. When the enzyme was under the low pH environment, it was not easy for enzyme to undergo thermal deactivation.
Breitenkamp, Kurt E. « Synthesis and Interfacial Behavior of Functional Amphiphilic Graft Copolymers Prepared by Ring-opening Metathesis Polymerization ». 2009. https://scholarworks.umass.edu/dissertations/AAI3349710.
Texte intégralchen, Yi-Wen, et 陳怡雯. « Preparation of Poly(ethylene glycol)-Cotaining Amphiphilic Graft Copolymers and Their Effect on the Immobilized enzyme ». Thesis, 2008. http://ndltd.ncl.edu.tw/handle/30978389657784427511.
Texte intégral國立臺灣科技大學
化學工程系
96
Enzyme immobilization is one of the most important techniques for increasing the stability of enzyme and recycling. In this study, it is intended to investigate the activity of enzyme after immobilization toward high and low molecular weight substrates. Amphiphilic copolymer comprising poly(acrylic acid)(PAAc) as the backbone and monomethoxy poly(ethylene glycol)(mPEG) as the grafts were synthesized and characterized. The copolymers were used for conjugation with different amounts of α- chymotrypsin as a pH-sensitive immobilized enzyme system. N-Benzoyl-L-Tyrosin ethyl ether was used as a low molecular weight substrate whereas bovine serum albumin was used as a high molecular substrate. Residual activity increased with increasing the mPEG amount and pH. The cleavage rate of bovin serum albumin was accelerated obviously for the experiments carried out in the pH 7 buffer solution. However, the excess amounts of mPEG would induce steric effect, thereby leading to slow cleavage rate.
Lin, Ya-Yun, et 林亞昀. « The Effects of Temperature on α-chymotrypsin modified by the Poly(ethylene glycol)-Containing Amphiphilic Graft Copolymers ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/26506263963066214373.
Texte intégral國立臺灣科技大學
化學工程系
98
Amphiphilic copolymers comprising poly(acrylic acid)(PAAc) as the backbone and monomethyl poly(ethylene glycol)(mPEG) as the grafts were synthesized and characterized. The copolymers were used for conjugation with different amounts of α-chymotrypsin. The activities of α-chymotrypsin before and after incorporating into the graft copolymers toward high and low molecular weight substrates were studied. N- Benzoyl-L-Tyrosine ethyl ether (BTEE) was used as a low molecular weight substrate and Azocasein was used as a high molecular substrate. Residual activity increased with increasing the pH and the mPEG content when BTEE was used, but it decreased with increasing the temperature and the mPEG amount when Azocasein was used due to the steric effect associated with the excessive amounts of mPEG. In addition, enzyme’s residual activity was reduced with temperature increment.
Szafraniec, Joanna. « Nanokapsuły polielektrolitowe z ciekłym rdzeniem do kontrolowanego podawania leków lipofilowych ». Praca doktorska, 2015. https://ruj.uj.edu.pl/xmlui/handle/item/45446.
Texte intégralChanda, Sananda. « Itaconate-based Periodically Grafted Polyesters ». Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2854.
Texte intégral