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Liquid Crystalline Copolymers (liquid + crystalline_copolymer)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Preparation and reflectance properties of new cholesteric liquid crystalline copolymers containing cholesteryl group

POLYMER ENGINEERING & SCIENCE, Issue 5 2009
Jinbao Guo
In this study, a new family of side-chain cholesteric liquid crystal copolymers derived from cholesterol substituents were synthesized. The chemical structures of the copolymers were validated by FTIR and 1H NMR. A wide-band reflective polarizer from the above copolymers with stable optical properties was developed. The pitch gradient was formed by molecular diffusion between adjacent liquid crystal layers based on these cholesteric copolymers with different pitch lengths, and the pitch gradient was further stabilized by UV crosslinking of the polymerizable monomers during the diffusion process. The stability of these systems as a function of time was investigated. The polymer network was validated by scanning electron microscopy and this network played an important role in stabilizing the pitch gradient of the system. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]

Synthesis and chiroptical properties of liquid crystalline copolymers containing azobenzene chromophores

POLYMER INTERNATIONAL, Issue 6 2007
Zhi Zheng
Abstract A series of new liquid crystalline copolymers, poly[((S)-2-methyl-1-butyl methacrylate)- co -(6-(4-(4-cyanophenylazo)phenoxy)hexyl methacrylate)], with different contents of chiral units of 17, 36, 54 and 78 mol% were synthesized. The structures and properties of the copolymers were characterized and evaluated using infrared, 1H NMR and UV spectroscopy, differential scanning calorimetry, gel permeation chromatography and circular dichroism (CD). The CD results suggested that absorptions of azobenzene chromophores were observed in films of copolymer containing 17, 36 or 54 mol% chiral units, but not in the film of copolymer containing 78 mol% chiral units. Also, CD values of the copolymeric films decreased with increasing chiral content. After irradiation with linear polarized light at 442 nm, CD values were changed in all the copolymeric films, and the CD values increased with decreasing chiral content in a nonlinear way, while the photoinduced change of chirality of the copolymers increased in a linear way with decreasing chiral content. The results are discussed in terms of interactions between structures and chiroptical properties. Copyright © 2007 Society of Chemical Industry [source]

Synthesis and characterization of thermotropic liquid crystalline poly(aryl ether ketone) copolymers with pendant 3-(trifluoromethyl) phenyl groups

POLYMER INTERNATIONAL, Issue 6 2006
Guibin Wang
Abstract Novel poly(aryl ether ketone) copolymers with pendant 3-(trifluoromethyl)phenyl groups were synthesized by the reaction of a crystal-disrupting monomer, 3-(trifluoromethyl)phenylhydroquinone (FH) and a mesogenic monomer, 4,4,-biphenol (BP) with 1,4-bis(p -fluorobenzoyl)benzene (BF). Thermotropic liquid crystalline behavior of the copolymers was investigated by means of differential scanning calorimetry, polarized optical microscope and wide-angle X-ray diffraction. As a result, the copolymers with the respective molar ratios of FH/BP/BF of 0/100/100,10/90/100 and 80/20/100,100/0/100 were semi-crystalline without liquid crystalline properties, and amorphous polymers, respectively. In contrast, copolymers with the molar ratio of FH/BP/BF of 20/80/100,70/30/100 had liquid crystalline characteristics. Interestingly, the formation of a highly ordered smectic phase was confirmed for copolymers with the molar ratio of FH/BP/BF of 20/80/100,50/50/100, respectively. All the liquid crystalline copolymers had a wide liquid crystalline temperature range (57,75 °C). Copyright © 2006 Society of Chemical Industry [source]