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Showing 1 to 20 of 152 for “"Chemistry, Polymer"”.
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Investigation of nitroxide-mediated thermal and photochemical reactions of living free radical polymerization.
… thesis deals primarily with living free radical polymerization (LFRP). Two main specific areas of this process have been studied; thermal and photochemical reaction sequences. Stoichiometric unimolecular initiators were found to be ideal probes for studying the reactions involved in the LFRP …
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Use of Rheology to Assess Structures in Polymer Nanocomposites
… to improve physico-mechanical properties of polymeric matrices have been the major research interest in composite science area in recent years. In many cases the so-called improved properties are considered to be linked to the irreversible particle aggregation, leading to formation of fractal …
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Fracture and Fatigue of a Self -Healing Polymer Composite Material
… to assess the fatigue behavior of a self-healing polymer. The inherent fatigue characteristics of the material are measured. A fatigue-life-extension-based protocol is established for characterizing self-healing under a cyclic loading. Retardation and arrest of the fatigue crack result from …
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Phenomenological Study of Enthalpy Relaxation and Physical Aging of Glucose, Fructose and Their Mixture
"Enthalpy relaxation of glucose, fructose and their mixtures was investigated using the Tool-Narayanaswamy-Monihan (TNM) and the Adam-Gibbs model parameters. The apparent activation energy was found to decrease as the fructose content increased. The value of parameter x increased with the fructose …
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Mechanophore-Linked Polymers for Studying Mechanochemical Response
… demonstrated that a mechanophore-linked polymer could be activated site-specifically via ultrasound-induced mechanical forces. Building on this idea, a method was established to synthesize mechanophore-linked poly(methyl acrylate) in an efficient manner using single electron transfer …
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The Synthesis, Characterization, and Properties of Stiff, Hydrophilic, Dendritic, Phenylacetylene Macromolecules
A series of phenylacetylene dendrimers bearing t-butyl ester groups on their periphery were prepared by a modified convergent growth scheme. The structures of these organic soluble compounds were confirmed by a variety characterization techniques including NMR, mass spectrometry, elemental …
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Solvophobically-Driven Folding of Non-Biological Oligomers and the Solid Phase Synthesis of Phenylacetylene Oligomers
The ordered sequence of monomers in phenylacetylene oligomers can serve as a repeating motif to produce helical structures in solution which posses a tubular cavity. Calculations with modest size oligomers show stable helical conformations with as few as 8 monomer units. Oligomers with triglyme …
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Synthesis, Characterization, and Ring -Opening Metathesis Polymerization Activity of Pentamethylcyclopentadienyl Osmium Complexes
Several acetonitrile complexes have been prepared; among these are [Cp*Os(CH 3CN)3][PF6], [CP*Os(PPh3)2(CH 3CN)][PF6], and [Cp*Os(COD)(CH3CN)]-[PF6 ]. Addition of 1,3-cyclooctadiene to Cp*2Os2Br 4 in refluxing ethanol affords the allyl complex Cp*Os(eta 3-C8H13)Br2. Treatment of the dimethyl …
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Surface Modification and Controlled Assembly of Molecular Materials
Single crystal molecular organization was investigated using coordination network crystals. Crystals that had molecules arranged as chains, such as catena-poly[dicyanobenzene-silver(I)]-triflate, were exposed to inhibitors specifically designed to bind at the growing surface. It was found that …
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Chromophore Arrays Based on Rigid Dendritic, Hyperbranched and Tetrahedrally Branched Architectures
Two tetrapodal structures containing four rigid arms incorporating anthracene chromophores were synthesized. Amorphous and luminescent properties of these compounds were characterized by thermal analysis and fluorescence spectroscopy.
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Improved Fiber Orientation Predictions for Injection Molded Composites
Our new orientation model is aphenomenological theory, and the value of the scalar factor to reduce the orientation change rate is determined by matching experimental data. Since the rheology of a fiber suspension is affected by the fiber orientation, a rheological experiment measuring the shear …
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Hexagonally-Packed Helical Oligo(m-Phenylene Ethynylene) Nanotubules via Structural Modification and Guest Templation
… on foldamer conformation when suspended in a polymer matrix, a thorough examination and comparison of foldamer solid-state morphology, and an extension of known solution-phase foldamer binding of terpenes to a multiple site domain.
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End-Group Modified Hyperbranched Polyetherimides and Their Blends With Linear Polymers
When used as a modifier for melt-processed blends, the HBP domain size was based upon end-group composition and Tg. Increasing the length of alkyl chain increased compatibility with a polyolefin matrix (PE). While no processing advantage was observed by the incorporation of HBPs, polyethylene tapes …
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Controlling Self -Assembly of Anisotropic, Rod-Like Polypeptides on Solid Surfaces
Advances in engineering of interfaces using self-assembled monolayers (SAMs) have focused on molecules with increased function and design. With an aim to establish principles that guide the assembly of new materials on surfaces and develop relationships between the molecular organization of the …
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Development of Functional Polymeric Materials for Microfluidic Systems
… In conclusion, the introduction of functional polymeric materials into microfluidics via direct photopolymerization has the potential to greatly simplify microfluidic fabrication processes, and to expand the application of traditional microfluidic systems.
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Morphology Effects on the Optical Properties of Phenylene Vinylenes From Nano-Scale to Bulk
… A series of phenylene vinylene oligomers and polymers were synthesized (1,4-distyrylbenzene (DSB), 4,4' -bis-hexyloxy-1,4-distyrylbenzene, 1,4-bis-hexyloxy-2,5-distyrylbenzene, 4,4'-distyrylstilbene, 1,4-bis[4-(3,5-di-tert -butylstyryl)styryl]benzene, poly-p-(phenylene vinylene) (PPV), and …
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Using Branching and Endgroups to Control the Physical Properties of Macromolecules: Systematic Studies of Etherimide Polymers
… modified polyetherimide hyperbranched polymers. Mono-functional groups were used to terminate an AB2-type polycondensation reaction, generating capped hyperbranched polymers (HBPs). The composition and constitution of the end groups controlled the solubility and thermal properties of …
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Folding-Driven, Nucleation -Elongation Polymerization of Phenylene Ethynylene Imines
As a result of the helical structure of the polymeric product, the polymerization of oligo(m-phenylene ethynylene) imines in solution should inherently show nucleation-elongation in chain growth. The evidence for this behavior was obtained from polymerizations conducted under conditions of …
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