Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 40 for “"controlled molecular weight"”.
-
Synthesis and characterization of m-aminophenoxide functionalized poly(tetramethylene oxide)
… to produce aromatic amine telechelic PTMO of controlled molecular weight and narrow molecular weight distribution. TrifHc anhydride was used to initiate a bifunctional cationic living polymerization of tetrahydrofuran (THP). An anhydrous solution of m-aminophenoxide was used to terminate the …
-
Synthesis and characterization of poly(arylene ether)s containing phosphorus, sulfur and heterocyclic pendant moieties
… to prepare poly(arylene ether)s of both high and controlled molecular weight. The novel poly(arylene ether)s based on phenolphthalein had glass transition temperatures ranging from 265 to 312 °C. Furthermore, the modulus of these macromolecules was significantly higher than that of typical …
-
The preparation of high performance polymers for composites and blends: A) thermally stable ion containing polymers B) epoxy and hydroxy functional polyolefin macromers
… ThE: second approach endeavored to form controlled molecular weight poly(ether-irTlides) via water soluble poly(amic acid) salt precursors. In this approach controlled molecular weight poly(amic acid)s were synthesized, and treated with stoichiometric quantities of tertiary or quaternary …
-
Synthesis and characterization of novel polyester/polysiloxane and polyester/arylphosphine oxide copolymers
Novel, high molecular weight poly(dimethylsiloxane) / cycloaliphatic polyester segmented copolymers were prepared and characterized. Specifically, polyesters based on dimethyl 1,4-cyclohexane dicarboxylate and 1,4-butanediol were employed. The copolymers were synthesized via a melt process using a …
-
Modification, curing and flame retardation of epoxy resin networks
… functionalized poly(arylene ether sulfone)s of controlled molecular weight were synthesized as soluble, but reactive thermoplastic modifiers for aromatic amine cured epoxy resins. These materials were characterized via spectroscopy, thermogravimetric analysis, differential scanning calorimetry …
-
Structure-property behavior of polyimide homopolymers, copolymers, and blends
Fully imidized, high molecular weight polyimide homopolymers and random segmented poly(siloxane imide) and poly(aryl ether imide) copolymers were prepared for use as environmentally stable, tough structural matrix resins, structural adhesives, and dielectric materials. Although polyimides are well …
-
Reversible stimulus-responsive polymers for the control of the surface interfacial and nanomechanical properties
… separation, and detection of biomolecules, controlled adhesion, friction, and lubrication in microfluidic systems, and force or displacement generation in micro- and nanoscale devices. Surface bound stimulusresponsive polymers are ideal candidates for above applications due to their …
-
Synthesis and characterization of poly(arylene ethers) and functionalized oligomers
Molecular weight control and endgroup functionalization in poly(arylene ether sulfones) has been achieved by two synthetic routes. The first utilizes DMSO/sodium hydroxide and aminophenol to introduce the amine functionality. This route, though synthetically useful, suffers from serious …
-
Siloxane modified polyurea and polyurethane urea segmented copolymers
High molecular weight polyether urea copolymers were synthesized using perfectly difunctional aromatic amine terminated polypropylene oxide (PPO) (2800 <Mn>) prepared via aluminum porphorin initiated coordination polymerization. The resulting segmented copolymer showed much higher tensile strength …
-
Copolymerization of a P-Vinylbenzyl-Ended Poly(Oxyethylene) With Vinyl Monomers and Some Reactions of Poly(Oxyethylene) Derivatives
Controlled free radical polymerization has gained in importance in recent years because it enables one to synthesize polymers with controlled molecular weight, narrow molecular weight distribution, and well defined architectures. In this work we have studied controlled copolymerizations of …
-
Synthesis and characterization of perfectly alternating segmented copolymers comprised of poly(dimethylsiloxane)s and engineering thermoplastics
… the solid state. The -(-A-B-)-n architecture and molecular design of these linear systems afforded thermodynamically microphase separated systems which gave rise to interesting copolymer properties. Each controlled molecular weight oligomeric segment, or homopolymer, was initally synthesized with …
-
Synthesis of novel methacrylate-containing polymers by anionic polymerization
… polymerization mechanisms. Parameters such as molecular weight, molecular weight distribution, stereochemistry, chain end functional groups, polymer architecture and sequence distribution may ideally be controlled with anionic polymerization. The vast majority of anionic syntheses have dealt …
-
Thermo-responsive Graft Copolymers based on Poly(Methyl Vinyl Ether): from Synthesis to Evaluation
… What has emerged from this work is that the controlled/living polymerization methods developed so far eliminate the limits in the design of novel types of graft copolymers with potential applications such as drug carriers, switchable amphiphiles, mineralization templates, etc... Several …
-
Studies of the cationic polymerisation of vinylic and energetic cyclic ether monomers
… In order to optimise the system, achieve controlled molecular weight polymers and understand the mechanism of polymerisation the effects of certain parameters on the molecular weight distribution, as determined by Size Exclusion Chromatography, have been examined. This shows the molecular …
-
Synthesis and Characterization of Polylactide-siloxane Block Copolymers as Magnetite Nanoparticle Dispersion Stabilizers
… is comprised of three reactions. Difunctional, controlled molecular weight polymethylvinylsiloxane oligomers with either aminopropyl or hydroxybutyl endgroups were prepared in ring-opening redistribution reactions. These oligomers were utilized as macroinitiators for ring-opening L-lactide to …
-
Synthesis and Non-Covalent Interactions of Novel Phosphonium-Containing Polymers
… a thermally stable ionic functionality that controlled molecular weight. Weak association was present with phosphonium ions at low ion concentrations below 7.7 mole %. The use of novel ionic bisacetoacetate monomers in the formation of networks from Michael addition reactions led to the …
-
Polymer Stabilized Magnetite Nanoparticles and Poly(propylene oxide) Modified Styrene-Dimethacrylate Networks
… materials. Hydrophilic triblock copolymers with controlled concentrations of pendent carboxylic acids were prepared. The triblock copolymers contain carboxylic acids in the central urethane segments and controlled molecular weight poly(ethylene oxide) tail blocks. They were utilized to prepare …
-
Synthesis and characterization of soluble, high temperature aromatic polyimides
High molecular weight, soluble polyimides were synthesized by a non-traditional synthetic route utilizing solution imidization techniques and diester-diacid derivatives of various commercially available dianhydrides. "One pot" syntheses were conducted using a solvent system of N-methylpyrrolidinone …
-
Synthesis, characterization and kinetic investigations of heterophase materials prepared using group transfer polymerization
… temperature range. The degree of control over molecular weight and molecular weight distribution rivals that afforded through living anionic techniques for the preparation of poly(alkyl methacrylate)s. The objectives of this research were many fold. The first was to establish GTP as a routine …
-
Synthesis and characterization of phosphorus containing poly(arylene ether) systems
… statistical copolymers, as well as polymers of controlled molecular weight and functionality, were also prepared via conventional techniques, yielding novel phosphorus containing compositions. Unique features of these poly (arylene ether phosphine oxide) s (PEPO) were discovered initially by …
Page 1 of 2