EBookClubs

Read Books & Download eBooks Full Online

EBookClubs

Read Books & Download eBooks Full Online

Book The Synthesis and Characterization of Di Tri and Radial block Copolymers Prepared of Polyisobutylene and Cyclic Ethers

Download or read book The Synthesis and Characterization of Di Tri and Radial block Copolymers Prepared of Polyisobutylene and Cyclic Ethers written by William Paul Francik and published by . This book was released on 1983 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Dissertation Abstracts International

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1983 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Synthesis and Characterization of Ionically Bonded Diblock Copolymers

Download or read book Synthesis and Characterization of Ionically Bonded Diblock Copolymers written by Lei Feng (Chemical engineer) and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Block copolymers consist of two or more incompatible polymer chains linked by covalent bonds. These block copolymer can separate into nanometer sized domains whose morphology depends upon the size of the block and interactions between them. The properties of block copolymers can be modified and potentially improved by introducing noncovalent interactions to replace covalent linkages between blocks to form supramolecular block copolymers. These kinds of materials combine the microphase separation inherent to block copolymers with the facile synthesis of supramolecular materials thereby affording new and unique materials. This dissertation focuses on synthesis and characterization of PS-b-PMA block copolymers with ion-pair junctions.Firstly, the chain-end sulfonated polystyrene ([omega]-sulfonated PS) was synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization and postpolymerization modification. In the postpolymerization modification two methods were investigated: in the first one, the polymer was converted to a thiol-terminated polymer by aminolysis. Then a sulfonic acid end-group was produced then by oxidation of the thiol end-group with m-chloroperoxybenzoicacid (m-CPBA); in the second method, the RAFT-polymerized polymer was directly sulfonated by oxidation with m-CPBA. After purification by column chromatography, [omega]-sulfonated PS was obtained by both methods with greater than 95% end-group functionality as measured by titration. The sulfonic acid end-group could be neutralized with various ammonium or imidazolium counter ions through acid-base or ionic metathesis reactions. These polymers with ionic end-group can be used as model supramolecular building blocks.Secondly, ammonium end functionalized polymethylacrylate (PMA) was synthesized directly by RAFT polymerization using functional RAFT agent. Then chain-end sulfonated polystyrene and ammonium end functionalized polymethylacrylate (PMA) were used to synthesize A-B block copolymers by two different methods: the first method was by mixing two oppositely charged end group functionalized polymers; the second method was to ionically bond a RAFT agent to the chain end of an end sulfonated polymer to generate a supramolecular macro RAFT agent then an A-B block copolymer was prepared by RAFT polymerization using supramolecular macro-RAFT agent. The polymerization kinetics were investigated and the molecular weight and the chemical structure of the block copolymers were characterized by 1H-NMR and SEC. The results show that the ion-bonded supramolecular block copolymer, PS-PMA, have been successfully prepared with controlled molecular weight and narrow distribution.Thirdly, the morphology of the ion-bonded supramolecular PS-PMA diblock copolymers were investigated by small-angle X-ray scattering (SAXS) and rheological techniques. Several covalently bonded PS-PMA block copolymers were synthesized by RAFT polymerization and their micro domain structures and rheology behaviors were also investigated. The results showed that the electrostatic interactions between the end ion groups are able to overcome the thermodynamic repulsion of two blocks result in the formation of diblock copolymers with similar behaviors and morphology of traditional covalent bonded diblock copolymers and their micro domain structures remain to high temperatures.

Book Silicon Containing Copolymers

Download or read book Silicon Containing Copolymers written by Sahar Amiri and published by Springer. This book was released on 2014-08-11 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicones have unique properties including thermal oxidative stability, low temperature flow, high compressibility, low surface tension, hydrophobicity and electric properties. These special properties have encouraged the exploration of alternative synthetic routes of well defined controlled microstructures of silicone copolymers, the subject of this Springer Brief. The authors explore the synthesis and characterization of notable block copolymers. Recent advances in controlled radical polymerization techniques leading to the facile synthesis of well-defined silicon based thermo reversible block copolymers are described along with atom transfer radical polymerization (ATRP), a technique utilized to develop well-defined functional thermo reversible block copolymers. The brief also focuses on Polyrotaxanes and their great potential as stimulus-responsive materials which produce poly (dimethyl siloxane) (PDMS) based thermo reversible block copolymers.

Book American Doctoral Dissertations

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1982 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Synthesis and Characterization of Well defined Amphiphilic Ionic Copolymers

Download or read book Synthesis and Characterization of Well defined Amphiphilic Ionic Copolymers written by Yuqing Liu (Polymer engineer) and published by . This book was released on 2011 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amphiphilic ionic block copolymers are promising materials for the fabrication of ion-exchange membranes in fuel cells, water purification and advanced molecular engineering applications, such as nanotemplating. For example, block copolymer architectures provide a route to fabricate membranes with tunable transport properties through polymer self assembly. A significant challenge in this field is the synthesis of amphiphilic copolymers, where the intrinsic immiscibility of the hydrophobic and hydrophilic monomers complicates polymerization. To address the immiscibility between sodium p-styrenesulfonate and styrene monomers, styrenesulfonate monomers were neutralized by hydrophobic trialkyl ammonium salts via ion-exchange reactions, and synthesized successfully by RAFT polymerization with low polydispersity (PDI). Diblock or triblock copolymers with well-defined architectures were obtained by sequential RAFT polymerization with styrene. These sulfonate groups were then converted to the sodium salt form via ion-exchange to obtain amphiphilic ionic block copolymers. It was observed that dimethyl n-alkyl ammonium salts of polystyrenesulfonate displayed thermo-reversible gelation behavior in low polarity organic solvents. The investigation of the gelation behavior as a function of temperature, concentration, and solvent was consistent with gelation driven by the ionic aggregation of the polymer as would be expected for polyelectrolyte surfactant complexes in non-polar solvents. Cationic amphiphilic block/graft copolymers containing quaternary ammonium salts were prepared by the RAFT polymerization of polystyrene-b-poly(vinylbenzyl chloride) (PS-b-PVBC) copolymers, and sequential post-polymerization quaternization of the PVBC blocks. PS-b-PVBEA-b-PS triblock copolymers with well-defined architectures were obtained and the ion conductivity of the corresponding membranes, as well as the morphology of the membranes, was investigated. To improve the mechanical properties of the membranes, different architectures, such as pentablock, heptablock and graft copolymers, were designed and synthesized by RAFT polymerization, and chemical crosslinking was employed to improve the mechanical properties and control the swelling in water. Lastly, a new method to prepare multiblock copolymers via a facile route was developed. Polytrithiocarbonates were prepared by condensation polymerization of a dicarboxylic acid functional trithiocarbonate and a diol, and the trithiocarbonate group was controlled by tuning the amount of acid catalyst and reaction time. The polytrithiocarbonate RAFT agents were used to polymerize PS, polystyrene-b-poly (tert-butylstyrene) (PS-b-PtBS), and PS-b-PVBC. The PDI of the polymers toward 2, but the PDI of the polymer blocks between two trithiocarbonate groups was narrow (1.1-1.3 for PS and PS-b-PtBS, and 1.46 for PS-b-PVBC). The PVBC segments were quaternized to achieve anionic amphiphilic multiblock copolymers.

Book Polyimides and other high temperature polymers

Download or read book Polyimides and other high temperature polymers written by K. L. Mittal and published by VSP. This book was released on 2003-03 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Containing 32 peer-reviewed papers, this volume documents the proceedings of the international symposium of the same name (held under the aegis of the Materials Science and Technology Conferences) in December of 2001. Devoted to research into high-temperature polymers, the papers are organized into sections dealing with synthesis, properties, and bulk characterization in the first half and surface modification, interfacial or adhesion aspects, and applications in the second. Annotation (c)2003 Book News, Inc., Portland, OR (booknews.com).

Book Synthesis and Characterization of Novel Polyisobutylene based Materials

Download or read book Synthesis and Characterization of Novel Polyisobutylene based Materials written by Lisa Kay Kemp and published by . This book was released on 2007 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Synthesis and Characterization of Block Copolymers

Download or read book Synthesis and Characterization of Block Copolymers written by and published by . This book was released on 1987 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polyether-Polyimide Block Copolymers; Three series of Polyether-Polyimide (PEPI) block copolymers were synthesized. Soft segments were poly(propylene glycol) (PPO) Mn = 2,000 and 4,000. Hard segments were pyromellitic dianhydride (PMDA) and di-(2-hydroxyethyl)-dimethylhydantoin (H). The hard segments were formed from 4,4'-diphenylmethane disocyanate (MDI) with PMDA or 95% PMDA and 5% H. The first series designated as PEPI-2K was synthesized with PPO-2,000, MDI and PMDA. The second series, PEPI-2KH, used PPO-2,000, MDI, 95% PMDA+ 5% H. The third series, PEPI-4K, used PPO-4,000, MDI and PMDA. PEPI copolymers in each series varied by weight percent of hard segment.

Book The Synthesis and Characterization of Block Copolymers

Download or read book The Synthesis and Characterization of Block Copolymers written by Jin-Long Hong and published by . This book was released on 1987 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polyether-Polyimide Block Copolymers; Three series of Polyether-Polyimide (PEPI) block copolymers were synthesized. Soft segments were poly(propylene glycol) (PPO) Mn = 2,000 and 4,000. Hard segments were pyromellitic dianhydride (PMDA) and di-(2-hydroxyethyl)-dimethylhydantoin (H). The hard segments were formed from 4,4'-diphenylmethane disocyanate (MDI) with PMDA or 95% PMDA and 5% H. The first series designated as PEPI-2K was synthesized with PPO-2,000, MDI and PMDA. The second series, PEPI-2KH, used PPO-2,000, MDI, 95% PMDA+ 5% H. The third series, PEPI-4K, used PPO-4,000, MDI and PMDA. PEPI copolymers in each series varied by weight percent of hard segment.

Book Comprehensive Dissertation Index

Download or read book Comprehensive Dissertation Index written by and published by . This book was released on 1989 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Synthesis and Characterization of Modified Block Copolymers

Download or read book Synthesis and Characterization of Modified Block Copolymers written by Chi-Fung Chu and published by . This book was released on 1988 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Synthesis and Characterization of Smart Block Copolymers for Biomineralization and Biomedical Applications

Download or read book Synthesis and Characterization of Smart Block Copolymers for Biomineralization and Biomedical Applications written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Self-assembly is a powerful tool in forming structures with nanoscale dimensions. Self-assembly of macromolecules provides an efficient and rapid pathway for the formation of structures from the nanometer to micrometer range that are difficult, if not impossible to obtain by conventional lithographic techniques [1]. Depending on the morphologies obtained (size, shape, periodicity, etc.) these self-assembled systems have already been applied or shown to be useful for a number of applications in nanotechnology [2], biomineralization [3, 4], drug delivery [5, 6] and gene therapy [7]. In this respect, amphiphilic block copolymers that self-organize in solution have been found to be very versatile [1]. In recent years, polymer-micellar systems have been designed that are adaptable to their environment and able to respond in a controlled manner to external stimuli. In short, synthesis of 'nanoscale objects' that exhibit 'stimulus-responsive' properties is a topic gathering momentum, because their behavior is reminiscent of that exhibited by proteins [8]. By integrating environmentally sensitive homopolymers into amphiphilic block copolymers, smart block copolymers with self assembled supramolecular structures that exhibit stimuli or environmentally responsive properties can be obtained [1]. Several synthetic polymers are known to have environmentally responsive properties. Changes in the physical, chemical or biochemical environment of these polymers results in modulation of the solubility or chain conformation of the polymer [9]. There are many common schemes of engineering stimuli responsive properties into materials [8, 9]. Polymers exhibiting lower critical solution temperature (LCST) are soluble in solvent below a specific temperature and phase separate from solvent above that temperature while polymers exhibiting upper critical solution temperatures (UCST) phase separate below a certain temperature. The solubility of polymers with ionizable moieties depends on the pH of the solution. Polymers with polyzwitterions, anions and cations have been shown to exhibit pH responsive self assembly. Other stimuli responsive polymers include glucose sensitive polymers, calcium ion-sensitive polymers and so on. Progress in living radical polymerization (LRP) methods [10] has made it possible for the facile synthesis of these block copolymer systems with controlled molecular weights and well defined architectures. The overall theme of this work is to develop novel smart block copolymers for biomineralization and biomedical applications. Synthesis and characterization of self-assembling thermoreversible ionic block copolymers as templates in biomimetic nanocomposite synthesis using a bottom-up approach is a novel contribution in this respect. Further, we have extended these families of copolymers to include block copolymer-peptide conjugates to enhance biological specificity. Future directions on this work will focus on enhancing the polymer templating properties for biomineralization by expanding the family of block copolymers with organic polypeptides and biological polypeptide scaffolds as well as a detailed understanding of the polymer-inorganic nanocomposites at the molecular level using small angle scattering analysis. Glucose responsive polymer hydrogels for drug delivery, polymer-ligand conjugates for non-viral therapy and thermoresponsive injectable photocrosslinkable hydrogels for posttraumatic arthritis cartilage healing are other applications of these novel copolymers synthesized in our work.