Download or read book Synthesis and Aqueous Solution Properties of New Hydrophilic hydrophilic Diblock Copolymers written by Lindsey Bailey and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Solution Behavior of Doubly Responsive Hydrophilic Block Copolymers written by Xueguang Jiang and published by . This book was released on 2010 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the synthesis of stimuli-sensitive hydrophilic polymers, particularly doubly responsive hydrophilic block copolymers, by controlled radical polymerizations and the study of their solution behavior in water. By incorporating a small amount of stimuli-responsive groups into the thermosensitive block of a hydrophilic block copolymer, the lower critical solution temperature (LCST) of the thermosensitive block can be tuned by a stimulus and multiple micellization/dissociation transitions can be achieved by combining two external triggers. Chapter 1 describes the synthesis and thermosensitive properties of two new watersoluble polystyrenics with a short oligo(ethyl glycol) pendant from each repeat unit and the study of hydrophobic end group effects on cloud points of thermosensitive polystyrenics. Well-defined polymers were prepared from monomer-based initiators via nitroxide-mediated polymerization and the alkoxyamine end groups were removed by tri(n-butyl)tin hydride, yielding thermoresponsive polystyrenics with essentially no end groups. The results showed that hydrophobic end groups could significantly change the cloud points and the molecular weight dependences of cloud points of polystyrenics. Chapter 2 presents the synthesis of thermo- and light-sensitive hydrophilic block copolymers, poly(ethylene oxide)-b-poly(ethoxytri(ethylene glycol) acrylate-co-o-nitrobenzyl acrylate), and their responsive behavior in dilute aqueous solutions. Dynamic light scattering and fluorescence spectroscopy studies showed that these copolymers were molecularly dissolved in water at lower temperatures and self-assembled into micelles at temperatures above the LCST of the thermosensitive block. Upon UV irradiation, the o-nitrobenzyl group was cleaved and the LCST of the thermosensitive block was increased, causing the dissociation of micelles into unimers. The resultant copolymers underwent thermo-induced reversible micellization at higher temperatures. Chapter 3 describes multiple micellization/dissociation transitions of thermo- and pH-sensitive hydrophilic block copolymers, poly(ethylene oxide)-b-poly(methoxydi(ethylene glycol) methacrylate-co-methacrylic acid), in response to temperature and pH changes. The LCST of the thermosensitive block can be reversibly tuned and precisely controlled by solution pH. Chapter 4 presents the study on multiple sol-gel-sol transitions of a 20.0 wt % aqueous solution of poly(ethylene oxide)-b-poly(ethoxytri(ethylene glycol) acrylate-co-o-nitrobenzyl acrylate) induced by temperature changes and UV irradiation. The solution underwent thermo-induced sol-gel-sol transitions. Upon UV irradiation to dissociate micelles, the gel was transformed into a free-flowing liquid, which upon heating underwent sol-gel-sol transitions again.

Download or read book Amphiphilic Polymer Co networks written by Costas S Patrickios and published by Royal Society of Chemistry. This book was released on 2020-04-23 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amphiphilic polymer co-networks (APCNs) are a type of polymeric hydrogel, their hydrophobic polymer segments and hydrophilic components produce less aqueous swelling, giving better mechanical properties than conventional hydrogels. This new class of polymers is attracting increasing attention, resulting in further basic research on the system, as well as new applications. This book focuses on new developments in the field of APCNs, and is organised in four sections: synthesis, properties, applications and modelling. Co-network architectures included in the book chapters are mainly those deriving from hydrophobic macro-cross-linkers, representing the classical approach; however, more modern designs are also presented. Properties of interest discussed include aqueous swelling, thermophysical and mechanical properties, self-assembly, electrical actuation, and protein adsorption. Applications described in the book chapters include the use of co-networks as soft contact lenses, scaffolds for drug delivery and tissue engineering, matrices for heterogeneous biocatalysis, and membranes of controllable permeability. Finally, an important theory chapter on the modelling of the self-assembly of APCNs is also included. The book is suitable for graduate students and researchers interested in hydrogels, polymer networks, polymer chemistry, block copolymers, self-assembly and nanomaterials, as well as their applications in contact lenses, drug delivery, tissue engineering, membranes and biocatalysis.

Download or read book Tuning Sol gel Phase Diagrams of Doubly Thermosensitive Hydrophilic Diblock Copolymers in Water written by Naixiong Jin and published by . This book was released on 2013 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the synthesis of stimuli-responsive hydrophilic diblock copolymers and the study of their behavior in water under various conditions. The polymers were made by "living"/controlled radical polymerization. Chapter 1 presents a background of this dissertation. Chapters 2-4 describe a family of doubly thermosensitive diblock copolymers with a small amount of carboxylic acid groups incorporated into either one or both blocks. The lower critical solution temperature (LCST) of the weak acid-containing block increases with increasing pH due to the ionization of carboxylic acid. Chapter 5 presents the preparation of pH-sensitive diblock copolymer micelle-embedded agarose hydrogels. Chapter 2 describes the synthesis and solution behavior of poly(methoxytri(ethylene glycol) acrylate-co-acrylic acid)-b-poly(ethoxydi(ethylene glycol) acrylate) (P(TEGMA-co-AA)-b-PDEGEA)). PTEGMA and PDEGEA are thermosensitive polymers with LCSTs of 58 and 9 °C [degree Celsius], respectively, in water. A 20 wt% aqueous solution of P(TEGMA-co-AA)-b-PDEGEA with pH of 3.11 underwent transitions from a free-flowing liquid, to a free-standing gel, to a hot liquid, and to a cloudy mixture upon heating. The Ts̳o̳l̳-̳g̳̳̳̳e̳̳l̳̳̳̳ [sol-to-gel transition temperature] and Tg̳̳̳̳e̳̳l̳̳̳̳-̳so̳l̳ [gel-to-sol transition temperature] are closely related to the LCSTs of the two blocks. Upon raising pH, the Tg̳̳̳̳e̳̳l̳̳̳̳-̳so̳l̳ increased, while the Ts̳o̳l̳-g̳̳̳̳e̳̳l̳̳̳̳ remained the same. Accordingly, only the upper boundary of the ̳so̳l̳-g̳̳̳̳e̳̳l̳̳̳̳ phase diagram shifted upward. Chapter 3 presents the tuning of Ts̳o̳l̳-g̳̳̳̳e̳̳l̳̳̳̳ of moderately concentrated aqueous solutions of doubly thermosensitive diblock copolymers by incorporating a small amount of AA groups into the lower LCST block and changing the solution pH. The AA content had a significant effect on the pH dependence of Ts̳o̳l̳-g̳̳̳̳e̳̳l̳̳̳̳-. Chapter 4 shows that by incorporating a small amount of carboxylic acid groups into both blocks of a doubly thermosensitive diblock copolymer, the C-shaped sol-gel phase diagram can be readily and reversibly shifted by changing the solution pH. Chapter 5 presents the fabrication of pH-sensitive diblock copolymer micelle-embedded agarose hydrogels. The gel properties were not significantly affected by the incorporation of the micelles even when the polymer concentration reached 5 mg/g. The pH-induced release of the payload from the core of micelles in a hybrid gel was studied. Chapter 6 presents conclusions and future work.

Download or read book Block Copolymers in Nanoscience written by Massimo Lazzari and published by John Wiley & Sons. This book was released on 2007-06-27 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first book to take a detailed look at one of the key focal points where nanotechnology and polymers meet provides both an introductory view for beginners as well as in-depth knowledge for specialists in the various research areas involved. It investigates all types of application for block copolymers: as tools for fabricating other nanomaterials, as structural components in hybrid materials and nanocomposites, and as functional materials. The multidisciplinary approach covers all stages from chemical synthesis and characterization, presenting applications from physics and chemistry to biology and medicine, such as micro- and nanolithography, membranes, optical labeling, drug delivery, as well as sensory and analytical uses.

Download or read book Thermo and PH sensitive Hydrophilic Block Copolymers written by Thomas G. O'Lenick and published by . This book was released on 2011 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the synthesis of a series of thermo- and pH-sensitive hydrophilic block copolymers and the study of their solution behavior in water. By incorporating a small amount of weak acid or base groups into the thermosensitive block(s) of a hydrophilic block copolymer, the LCST of the thermosensitive block(s) can be modified by changing the solution pH. Accordingly, the critical micellization temperature (CMT) and the sol-gel transition temperature (T[subscript sol-gel]) of the block copolymer in water can be tuned. Chapter 1 describes the synthesis of thermo- and pH-sensitive poly(methoxydi(ethylene glycol) methacrylate-co-methacrylic acid)-b-PEO-b-poly(methoxydi(ethylene glycol) methacrylate-co-methacrylic acid) and the study of sol-gel transitions of its aqueous solutions at various pH values. The CMT of the 0.2 wt% solution and the T[subscript sol-gel] of the 12.0 wt% solution of this copolymer can be varied over a large temperature range. By judiciously controlling temperature and pH, multiple sol-gel-sol transitions were realized. Chapter 2 presents a systematic study of pH effect on rheological properties of micellar gels formed from 10.0 wt% aqueous solutions of thermo- and pH-sensitive poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid)-b-PEO-b-poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid). With the increase of pH, the sol-gel transition became broader. The plateau moduli (G[subscript N]) evaluated from frequency sweeps at T/T[subscript sol-gel] of 1.025, 1.032, and 1.039 decreased with the increase of pH from 3.00 to 5.40 with the largest drop observed at pH = ~ 4.7. The decrease in G[subscript N] reflects the reduction of the number of bridging chains. The ionization of carboxylic acid introduced charges onto the thermosensitive blocks and made the polymer more hydrophilic, facilitating the formation of loops and dangling chains. Chapter 3 presents the synthesis of PEO-b-poly(methoxydi(ethylene glycol) methacrylate-co-2-(N-methyl-N-(4-pyridyl)amino)ethyl methacrylate) with the thermosensitive block containing a catalytic 4-N, N-dialkylaminopyridine and the study of the effect of thermo-induced micellization on its activity in the hydrolysis of p-nitrophenyl acetate. The CMTs of this copolymer at pH of 7.06 and 7.56 were 40 and 37 °C, respectively. Below CMT, the logarithm of initial hydrolysis rate changed linearly with 1/T. Above CMT, the reaction rate leveled off, which is presumably because it was controlled by mass transport to the core of micelles above CMT.

Download or read book Design and Precise Synthesis of Thermoresponsive Polyacrylamides written by Keita Fuchise and published by Springer. This book was released on 2014-05-22 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the author describes versatile and easy-to-use methods to control the properties of thermoresponsive polyacrylamides by developing novel synthetic methods for end-functionalized poly(N-isopropylacrylamide) (PNIPAM) and block copolymers of poly(N,N-diethylacrylamide) (PDEAA). The synthesis of various urea end-functionalized PNIPAMs was achieved by the atom transfer radical polymerization (ATRP) and the click reaction. The phase transition temperature of PNIPAM in water was controlled depending on the strength of the hydrogen bonding of the urea groups introduced at the chain end of the polymer. Novel living polymerization methods for N,N-dimethylacrylamide and N,N-diethylacrylamide were developed by group transfer polymerization (GTP) using a strong Brønsted acid as a precatalyst and an amino silyl enolate as an initiator. This process enabled the precise synthesis of PDEAA and its block copolymers—namely, thermoresponsive amphiphilic block copolymers and double-hydrophilic block copolymers.

Download or read book Temperature Responsive Polymers written by Vitaliy V. Khutoryanskiy and published by John Wiley & Sons. This book was released on 2018-05-31 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: An authoritative resource that offers an understanding of the chemistry, properties and applications of temperature-responsive polymers With contributions from a distinguished panel of experts, Temperature-Responsive Polymers puts the focus on hydrophilic polymers capable of changing their physicochemical properties in response to changes in environmental temperature. The contributors review the chemistry of these systems, and discuss a variety of synthetic approaches for preparation of temperature-responsive polymers, physicochemical methods of their characterisation and potential applications in biomedical areas. The text reviews a wide-variety of topics including: The characterisation of temperature-responsive polymers; Infrared and Raman spectroscopy; Applications of temperature-responsive polymers grafted onto solid core nanoparticles; and much more. The contributors also explore how temperature-responsive polymers can be used in the biomedical field for applications such as tissue engineering. This important resource: Offers an important synthesis of the current research on temperature-responsive polymers Covers the chemistry, the synthetic approaches for presentation and the physiochemical method of temperature-responsive polymers Includes a review of the fundamental characteristics of temperature-responsive polymers Explores many of the potential applications in biomedical science, including drug delivery and gene therapy Written for polymer scientists in both academia and industry as well as postgraduate students working in the area of stimuli-responsive materials, this vital text offers an exploration of the chemistry, properties and current applications of temperature-responsive polymers.

Download or read book Synthesis and Characterisation of Methacrylate based Water soluble Diblock and Triblock Copolymers for Drug Dispersion in Aqueous Media written by Giovanni Francesco Unali and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterisation of Novel Ionic Block Copolymers written by Andrew Brian Lowe and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Hydrogel Forming Thermo responsive Block Copolymers of Increasing Structural Complexity written by Anna Miasnikova and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work describes the synthesis and characterization of stimuli-responsive polymers made by reversible addition-fragmentation chain transfer (RAFT) polymerization and the investigation of their self-assembly into "smart" hydrogels. In particular the hydrogels were designed to swell at low temperature and could be reversibly switched to a collapsed hydrophobic state by rising the temperature. Starting from two constituents, a short permanently hydrophobic polystyrene (PS) block and a thermo-responsive poly(methoxy diethylene glycol acrylate) (PMDEGA) block, various gelation behaviors and switching temperatures were achieved. New RAFT agents bearing tert-butyl benzoate or benzoic acid groups, were developed for the synthesis of diblock, symmetrical triblock and 3-arm star block copolymers. Thus, specific end groups were attached to the polymers that facilitate efficient macromolecular characterization, e.g by routine 1H-NMR spectroscopy. Further, the carboxyl end-groups allowed functionalizing the various polymers by a fluorophore. Because reports on PMDEGA have been extremely rare, at first, the thermo-responsive behavior of the polymer was investigated and the influence of factors such as molar mass, nature of the end-groups, and architecture, was studied. The use of special RAFT agents enabled the design of polymer with specific hydrophobic and hydrophilic end-groups. Cloud points (CP) of the polymers proved to be sensitive to all molecular variables studied, namely molar mass, nature and number of the end-groups, up to relatively high molar masses. Thus, by changing molecular parameters, CPs of the PMDEGA could be easily adjusted within the physiological interesting range of 20 to 40°C. A second responsivity, namely to light, was added to the PMDEGA system via random copolymerization of MDEGA with a specifically designed photo-switchable azobenzene acrylate. The composition of the copolymers was varied in order to determine the optimal conditions for an isothermal cloud point variation triggered by light. Though reversible light-induced solubility changes were achieved, the differences between the cloud points before and after the irradiation were small. Remarkably, the response to light differed from common observations for azobenzene-based systems, as CPs decreased after UV-irradiation, i.e with increasing content of cis-azobenzene units. The viscosifying and gelling abilities of the various block copolymers made from PS and PMDEGA blocks were studied by rheology. Important differences were observed between diblock copolymers, containing one hydrophobic PS block only, the telechelic symmetrical triblock copolymers made of two associating PS termini, and the star block copolymers having three associating end blocks. Regardless of their hydrophilic block length, diblock copolymers PS11 PMDEGAn were freely flowing even at concentrations as high as 40 wt. %. In contrast, all studied symmetrical triblock copolymers PS8-PMDEGAn-PS8 formed gels at low temperatures and at concentrations as low as 3.5 wt. % at best. When heated, these gels underwent a gel-sol transition at intermediate temperatures, well below the cloud point where phase separation occurs. The gel-sol transition shifted to markedly higher transition temperatures with increasing length of the hydrophilic inner block. This effect increased also with the number of arms, and with the length of the hydrophobic end blocks. The mechanical properties of the gels were significantly altered at the cloud point and liquid-like dispersions were formed. These could be reversibly transformed into hydrogels by cooling. This thesis demonstrates that high molar mass PMDEGA is an easily accessible, presumably also biocompatible and at ambient temperature well water-soluble, non-ionic thermo-responsive polymer. PMDEGA can be easily molecularly engineered via the RAFT method, implementing defined end-groups, and producing different, also complex, architectures, such as amphiphilic triblock and star block copolymers, having an analogous structure to associative telechelics. With appropriate design, such amphiphilic copolymers give way to efficient, "smart" viscosifiers and gelators displaying tunable gelling and mechanical properties.

Download or read book Synthesis of dye labelled Thermoresponsive Block Copolymers by Raft Polymerization written by Mariana Beija and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Double hydrophilic diblock copolymers comprising a thermoresponsive block have gained increasing attention due to their capability of self-assembling in micelles by a temperature change. However, very few fluorescence studies were devoted to investigate their conformation and dynamics both at the air-water interface and in aqueous solutions. In this work, block copolymers composed of a thermoresponsive block of N,N- iethylacrylamide (DEA) and a hydrophilic block of N,N-dimethylacrylamide (DMA) or a reactive block [statistical copolymer of DMA and N-acryloxysuccinimide (NAS)] were prepared by RAFT polymerization. These block copolymers were functionalized at the hydrophilic chain-end by a Rhodamine B or Malachite Green dye using either a pre- or a post-polymerization strategy. In the first case, Rhodamine B and Malachite Green amino derivatives were synthesized for the preparation of dyelabelled chain transfer agent (CTA), which led directly the alpha-dye-labelled block copolymers. Alternatively, the block copolymers were prepared using a precursor CTA and further functionalized with the dye amino derivative. The thermoresponsive behaviour of these polymers and of amphiphilic block copolymers of DEA and N-decylacrylamide was studied at the air-water interface and in Langmuir-Blodgett films using AFM and confocal fluorescence microscopy. Fluorescence emission and anisotropy, light scattering and 1H NMR studies were performed to investigate their behaviour in aqueous solutions.

Download or read book Glycopolymer Code written by C. Remzi Becer and published by Royal Society of Chemistry. This book was released on 2015-03-23 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: Glycopolymers are important for cell signalling, recognition pathways, and their role in the immune system. They are gaining attention for new applications in tissue engineering and drug delivery. Glycopolymer Code discusses the preparation, characterization and applications of glycopolymers providing a complete overview of the topic with examples from the latest research. Specific chapters cover both basic and advanced synthesis techniques to prepare glycopolymers, the analytical techniques used to investigate lectin receptor glycopolymer interactions, the properties and types of lectins that are widely used to understand the multivalent interactions and various applications of synthetic glycopolymers. With contributions from leading researchers in the field, the book is a unique source for graduates and academics new to the subject and already working in the area of glycopolymers.

Download or read book Design Synthesis and Characterization of New Phosphazene Related Materials and Study the Structure Property Correlations written by Zhicheng Tian and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The work described in this thesis is divided into three major parts, and all of which involve the exploration of the chemistry of polyphosphazenes. The first part (chapters 2 and 3) of my research is synthesis and study polyphoshazenes for biomedical applications, including polymer drug conjugates and injectable hydrogels for drug or biomolecule delivery. The second part (chapters 4 and 5) focuses on the synthesis of several organic/inorganic hybrid polymeric structures, such as diblock, star, brush and palm tree copolymers using living cationic polymerization and atom transfer radical polymerization techniques. The last part (chapters 6 and 7) is about exploratory synthesis of new polymeric structures with fluorinated side groups or cycloaliphatic side groups, and the study of new structure property relationships.Chapter 1 is an outline of the fundamental concepts for polymeric materials, as such the history, important definitions, and some introductory material for to polymer chemistry and physics. The chemistry and applications of phopshazenes is also briefly described.Chapter 2 is a description of the design, synthesis, and characterization of development of a new class of polymer drug conjugate materials based on biodegradable polyphosphazenes and antibiotics. Poly(dichlorophosphazene), synthesized by a thermal ring opening polymerization, was reacted with up to 25 mol% of ciprofloxacin or norfloxacin and three different amino acid esters (glycine, alanine, or phenylalanine) as cosubstituents via macromolecular substitutions. Nano/microfibers of several selected polymers were prepared by an electrospinning technique. The hydrolysis rate and the antibiotic release profile can be well tuned by either the polymer compositions, or the surface area monitored by a six week in vitro hydrolysis experiment. All the polymers gave a near-neutral hydrolysis environment with the pH ranging from 5.9--6.8. In an in vitro antibacterial test against E.coli, the antibacterial activity of the hydrolysis media was maintained as long as the polymer hydrolysis continued.Chapter 3 is concerned with the development of a class of injectable and biodegradable hydrogels based on water-soluble poly(organophosphazenes) containing oligo(ethylene glycol) methyl ethers and glycine ethyl esters. The hydrogels can be obtained by mixing [alpha]-cyclodextrin aqueous solution and poly(organophosphazenes) aqueous solution in various gelation rates depending on the polymer structures and the concentrations. The rheological measurements of the supramolecular hydrogels indicate a fast gelation process and flowable character under a large stain. The hydrogel system also exhibits structure-related reversible gel-sol transition properties at a certain temperature. The formation of a channel-type inclusion complex induced gelation mechanism was studied by DSC, TGA, 13C CP/MAS NMR and X-ray diffraction techniques. In vitro bovine serum albumin release of the hydrogel system was explored and the biodegradability of poly(organophosphazenes) was studied.Chapter 4 outlines the preparation of a number of amphiphilic diblock copolymers based on poly[bis(trifluoroethoxy)phosphazene] (TFE) as the hydrophobic block and poly(dimethylaminoethylmethacrylate) (PDMAEMA) as the hydrophilic block. The TFE block was synthesized first by the controlled living cationic polymerization of a phosphoranimine, followed by replacement of all the chlorine atoms using sodium trifluoroethoxide. To allow for the growth of the PDMAEMA block, 3-azidopropyl-2-bromo-2-methylpropanoate, an atom transfer radical polymerization (ATRP) initiator, was grafted onto the endcap of the TFE block via the 'click' reaction followed by the ATRP of 2-(dimethylamino)ethyl methacrylate (DMAEMA). Once synthesized, micelles were formed by a standard method and their characteristics were examined using fluorescence techniques, dynamic light scattering, and transmission electron microscopy. The critical micelle concentrations of the diblock copolymers as determined by fluorescence techniques using pyrene as a hydrophobic probe were between 3.47 and 9.55mg/L, with the partition equilibrium constant of pyrene in these micelles ranging from 0.12x105-1.52x105. The diameters measured by dynamic light scattering were 100-142nm at 25oC with a narrow distribution, which were also confirmed by transmission electron microscopy. Chapter 5 is a report on the design and assembly of polyphosphazene materials based on the non-covalent "host--guest" interactions either at the terminus of the polymeric main-chains or the pendant side-chains. The supramolecular interaction at the main chain terminus was used to produce amphiphilic palm-tree like pseudo-block copolymers via host-guest interactions between an adamantane end-functionalized polyphosphazene and a 4-armed [beta]-cyclodextrin ([beta]-CD) initiated poly[poly(ethylene glycol) methyl ether methacylate] branched-star type polymer. The formation of micelles of the obtained amphiphiles was analyzed by fluorescence technique, dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The supramolecular interactions involving polymer side-chains were achieved between polyphosphazenes with [beta]-CD pendant units and other polyphosphazene molecules with adamantyl moieties on the side-chains. These interactions worked as physical crosslinks which were responsible for the formation of a supramolecular hydrogel. The results of this work demonstrated the synthetic possibilities for these novel polymeric structures. These materials show potential for applications as smart drug delivery micro-vehicles, responsive hydrogels, and self-healing materials.Chapter 6 is an investigation of the influence of bulky fluoroalkoxy side groups on the properties of polyphosphazenes. A new series of mixed-substituent high polymeric poly(fluoroalkoxyphosphazenes) containing trifluoroethoxy and branched fluoroalkoxy side groups was synthesized and characterized by NMR and GPC methods. These polymers contained 19--29 mol% of di-branched hexafluoropropoxy groups or 4mol% of tri-branched tert-perfluorobutoxy groups, which serve as regio-irregularities to reduce the macromolecular microcrystallinity. The structure--property correlations of the polymers were then analyzed and interpreted by several techniques: specifically by the thermal behavior by DSC and TGA methods, the crystallinity by wide-angle X-ray diffraction, and the surface hydrophobicity/oleophobicity by contact angle measurements. Ultraviolet crosslinkable elastomers were prepared from the new polymers through the incorporation of 3mol% of 2-allylphenoxy and photo-irradiation. The mechanical properties and the elastomeric deformation--recovery behavior were then monitored by varying the time of ultraviolet irradiation. Side reactions detected during the synthesis of the high polymers, such as side group exchange reactions and alpha-carbon attack, were analyzed via use of a cyclic trimer model system.Chapter 7 is an outline of the exploratory synthesis of a new series of phosphazene model cyclic trimers and single- and mixed- substituent high polymers containing cyclic aliphatic rings, --CnH2n-1 (where n = 4--8). The cylco-aliphatic side group containing phosphazenes expand the structural and property boundaries of phosphazene chemistry, and suggest additional approaches for studying slow macromolecular substitution reactions and substituent exchange reactions. Polymer structure--property relationships are interpreted and correlated to glass transition temperatures, thermal decomposition temperatures, hydrophobicity, and membrane mechanical properties. Films prepared from these polymers are low cost, tough and non-adhesive. They can be used in variety of applications especially where transparency is important.

Download or read book Phosphorus Based Polymers written by Sophie Monge and published by Royal Society of Chemistry. This book was released on 2014-05-30 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive overview of the synthesis of different phosphorus-containing polymers and their uses in biomedical, environmental and energy applications.

Download or read book Synthesis and Properties of Hydrophilic Copolymers written by T. P. Davis and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Self assembling Polymers Using Hydrogen Bonding Or Hydrophobic Effect written by Xinjun Yu and published by . This book was released on 2015 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation is mainly based on the works of synthesis and characterization of self-assembling polymers using hydrogen bonding or hydrophobic interactions. Firstly, N-alkyl urea peptoid oligomer was synthesized as backbone of supramolecular polymers through three step repetition cycles with high yield. One N-alkyl urea peptoid precursor was explored to simplify the synthetic process. 4 different functional groups were converted from one precursor. Then 2-ureido-4[1H]-pyrimidinone (UPy) group which is a quadruple hydrogen bonding system was incorporated to N-alkyl urea peptoid oligomers to generate supramolecules. With the experience of UPy unit, we further explored UPy containing monomer to make organogelators. Three different monomers with different Tg values were copolymerized using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Organogels were afforded in both chloroform and dichlorobenzene. Critical gelation concentration and mechanic properties of organogels were examined. Cooperating another novel monomer containing pyrene unit to the above copolymers, fluorescent organogels were achieved which were suitable for potential up-conversion applications. In addition to pyrene, anthracene is another molecule which shows great up-conversion property. A series of Poly[(9-anthrylmethyl methacrylate)-co-(methyl methacrylate)] (Poly(AnMMA-co-MMA)) with different AnMMA ratios were synthesized via RAFT polymerization, resulting in tunable inter-chromophore distances. These polymers can serve as emitters, with PtOEP as sensitizer, in triplet-triplet annihilation up-conversion (TTA-UC) systems. TTA-UC intensity of the Poly(AnMMA-co-MMA)/PtOEP mixtures displays interesting dependence on the AnMMA ratio in the polymer. Interactions between chromophores on the same polymer chain play the key role in affecting the TTA-UC intensity in these systems. It is critical to minimize intra-chain chromophore quenching in order to achieve high UC intensity. Hydrophobic effect was used to obtain a hybrid photosensitizer. By integrating amphiphilic block copolymer poly(N-isopropylacrylamide-b-styrene) (PNIPAAm-b-styrene) stabilized silver nanoparticles (Ag NPs) with hematoporphyrin (HP), HP was trapped by polystyrene block through hydrophobic effects. Hydrophilic block can increase the solubility of this photosensitizer in aqueous solution. This hybrid photosensitizer was demonstrated to enhance singlet oxygen production. Finally, a self-immolative polymer was made with a kinetically stable polymer backbone, whose chain end can respond to external stimulus by triggering a head-to-tail depolymerizaiton. Electrospining was used to fabricate nano-scale fibers which can be utilized in potential drug delivery system.