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 60 for “"main-chain"”.
-
Observation of main chain chirality in isotactic polystyrene
The main objective of this thesis was to study main chain chirality in isotactic polystyrene. A stereoselective titanium based catalyst was developed and compared with other group IV metal catalysts in terms of activity and selectivity in olefin polymerization.
-
Morphology and crystal structure of random, main chain, semi-flexible, thermotropic liquid crystal polymers
"The crystal structure and morphology of random, main chain, thermotropic liquid crystal polymers (LCP's) of equimolar amounts of the following structural units (with n equal to 4, 5, 6 and 7 in ""A"") have been examined by electron microscopy and diffraction:(DIAGRAM, TABLE OR GRAPHIC …
-
Phase Transitions and the Effect of External Fields in Thermotropic Main Chain Liquid Crystal Systems
… investigate the unique behavior of thermotropic main chain liquid crystal polymers with regard to phase transitions and their response to surfaces and external fields. Three different aromatic polymers were utilized in this study, including two constitutional isomers with periodic and aperiodic …
-
Polymers containing calix[4]arenes and triptycenes : new syntheses, properties and applications
… 2, early investigations on the synthesis of main-chain calix[4]arene polymers are introduced. High molecular-weight main-chain calixarene homopolymers via linkages on lower rims are synthesized by the polymerization based on acetylenic coupling reaction. The conformation of calixarene …
-
Poly(ionic liquid) stabilizers and new synthetic approaches
The main focus of the present thesis was to investigate the stabilization ability of poly(ionic liquid)s (PILs) in several examples as well as develop novel chemical structures and synthetic routes of PILs. The performed research can be specifically divided into three parts that include synthesis …
-
Synthesis, Molecular Weight Characterization and Structure-Property Relationships of Ammonium Ionenes
… with quaternized nitrogen groups in the main chain. Ionenes are commonly referred to as x,y-ionene, where x and y represent the number of methylene groups between quaternized nitrogens. Synthesis of aliphatic ammonium ionenes has been studied since the early twentieth century; however, …
-
Analysis of hairy-rod polyimides for photoalignment
… at higher fluences, which was dependent on the main chain, side chain combination. Minimal changes in the UV/VIS and FTIR absorption spectra were found for fluences at which pretilted LC alignment occurred. For higher fluences photodegradation could be observed in the FTIR spectra. AFM …
-
The synthesis of new electro-optic polymers.
… These are the first known readily soluble main chain polymers that exhibit SHG behavior. The second type of monomers were acrylates containing substituted phenyl esters of benzoic acid as mesogenic (pendant) groups. Specifically, the mesogenic group contained an …
-
Some non-cellulosic b-D-Glycans from plant sources
… to be characterised by linked D-pyranosyl a main chain consisting of β -(1-44)- sugars. The polysaccharides were, however, different in structural features in a manner apparently related to their respective locations within the organs of the plants concerned. The polysaccharides were isolated …
-
Optically active photoresponsive multifunctional polymeric materials
… methacrylic polymers bearing in the side chain the chiral cyclic (S)-3-hydroxypyrrolidine moiety interposed between the main chain and the trans-azoaromatic chromophore, substituted or not in the 4’ position by an electron-withdrawing group. In these materials, the presence of a rigid …
-
Introduction of a Novel Family of Bitopic N-Heterocyclic Carbenes
… for the formation of bimetallic complexes, main-chain organometallic polymers, and supramolecular structures. These complexes allow for significant versatility in catalytic properties, solubility, and selectivity. The synthesis of the novel intermediate compounds, thiones, and bimetallic …
-
Design, Synthesis and Self-Assembly of Polymeric Building Blocks and Novel Ionic Liquids, Ionic Liquid-Based Polymers and Their Properties
… and guest polymeric building blocks provided chain-extended and tri-armed homopolymers, and diblock and tri-armed copolymers. A supramolecular graft copolymer was formed from a main-chain poly(ester crown ether) and a paraquat terminated polystyrene. This comb-like copolymer was characterized …
-
Infrared Frequency Shifting in Thermally- and Mechanically-Stressed Polymers (Anharmonicity, Nonequilibrium, Ftir, Fourier, Transform, Spectrometer)
… the spacing of the constituents of a polymer chain, usually resulting in the reduction of the molecular vibration frequency as revealed by the transmission infrared spectroscopy of stressed polymer films. The effect of stress and temperature on infrared frequency shifting and band asymmetry in …
-
Synthesis and characterization of conducting polymers with new architectural motifs
… 2,2'-biphenyl units into the polymer main chain were synthesized. The potential utility of the 2,2'-biphenyl unit as a scaffold to facilitate the t-n interactions between thiophene oligomers was explored. The linkage of the thiophene to the biphenyl was varied between the a- or …
-
Novel cellulose esters
… acetate (CATA), cellulose esters of long chain linear aliphatic acids, and cellulose acetate laurate (CAL). The derivatives were synthesized in a homogeneous reaction medium of DMAc/LiCl. Several esterification chemistries were used including one based on reactions with TsCl (para-tolulene …
-
Facile protein and amino acid substitution reactions and their characterization using thermal, mechanical and optical techniques
The work focused on addressing four main objectives. The first objective was to quantify protein and amino acid substitution reactions. Michael addition reactions were used to modify the amino acids and protein. Amino acids alanine, cysteine, and lysine, and protein ovalbumin (OA) were substituted …
-
Barracuda: The power of l-polling in proof of stake blockchains
Blockchain is a database of storing sequential events as a chain of blocks consistently across a distributed set of nodes. A fundamental problem in doing so is to decide where to put the next block and who should do it in a Sybil-resistant manner. To solve this problem, typically, a node is elected …
-
Characterization of polyphenoxy-ethylphenoxyphosphazene-bulk sealant applications
Polymer chemistry has primarily been a main chain carbon-based science, but recently the usage of inorganic polymeric materials has increased with polyphosphazene research leading the way. The credit for the increased interest in the field of phosphazene chemistry arises from the unique physical …
-
Radiation induced degradation of elastomers.
… degraded thermally by hydrolytic scission of the main chain and chain reformation by condensation of the silanol chain end groups. However,predominant chain reformation was observed during thermal degradation studies and it was believed that this was a consequence of the reformation of chains cut …
Page 1 of 3