Synthesis and transition temperatures of some novel, chiral nematic, laterally attached, side-chain, siloxane polymers

1992 ◽  
Vol 2 (1) ◽  
pp. 119 ◽  
Author(s):  
Russell A. Lewthwaite ◽  
George W. Gray ◽  
Kenneth J. Toyne
Keyword(s):  
Side Chain ◽  
Transition Temperatures ◽  
Chiral Nematic ◽  
Siloxane Polymers

Side-Chain LC Block Copolymers with Well Defined Structures Prepared by Living Anionic Polymerization. 2: Effect of the Glass Transition Temperature of Amorphous Segments on the Phase Behaviour and Structure of the LC Segment

1998 ◽  
Vol 10 (1) ◽  
pp. 131-138 ◽  
Author(s):  
Masayuki Yamada ◽  
Tomomichi Itoh ◽  
Akira Hirao ◽  
Sei-Ichi Nakahama ◽  
Junji Watanabe
Keyword(s):  
Glass Transition ◽  
Anionic Polymerization ◽  
Diblock Copolymers ◽  
Domain Size ◽  
Phase Behaviour ◽  
Side Chain ◽  
Isotropic Phase ◽  
Transition Temperatures ◽  
Living Anionic Polymerization ◽  
Methyl Styrene

We have prepared two classes of LC diblock copolymers, OcSt-b-LC and MeStb-LC, by living anionic polymerization. These are composed of the side-chain LC polymer as one segment and two different amorphous polymers, poly(octyl styrene) (OcSt) and poly(α-methyl styrene) (MeSt), as the other segment. OcSt and MeSt segments have glass transition temperatures of −60 °C and 160 °C respectively, which are relatively lower and higher than the transition temperatures of crystal–SA (∼90 °C) and SA–isotropic (∼130 °C) in the LC segment. In OcSt-b-LC the lamellar domain size decreases gradually from that of the crystal phase to that of the isotropic phase, indicating that the global conformation of the backbone changes throughout the SA temperature region. In MeSt-b-LC, in contrast, no change in the lamellar size is observed and the crystallinity of the LC segment is reduced in comparison with that in OcSt-b-LC while the liquid crystal is well formed. Such a distinction between two copolymer systems, arising from an interplay between the LC and amorphous segments, shows that the global conformation of the backbone is significant for understanding the phase behaviour and structure of side-chain LC polymers.

scholarly journals Thermotropic chiral nematic side-chain polymers and cyclic oligomers

1996 ◽  
Vol 21 (6) ◽  
pp. 1211-1233 ◽  
Author(s):  
Shaw H Chen ◽  
Hongqin Shi ◽  
John C Mastrangelo ◽  
Jane J Ou
Keyword(s):  
Side Chain ◽  
Chiral Nematic ◽  
Cyclic Oligomers

Properties and Structure of Elastomers

1966 ◽  
Vol 39 (4) ◽  
pp. 881-896 ◽  
Author(s):  
Joginder Lal ◽  
Kenneth W. Scott
Keyword(s):  
Tensile Strength ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Alkyl Group ◽  
Side Chain ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Dynamic Mechanical ◽  
Alkyl Ethers

Abstract The glass transition temperatures of high molecular weight poly (vinyl n-alkyl ethers) decrease with increasing length of the n-alkyl group. On lengthening the n-alkyl group, 14 per cent of the specific volume increase is free volume. Branching or substitution in the alkyl group of the polymer increases the Tg value. A comparison of poly (vinyl n-alkyl ethers) and polymers of normal α-olefins shows that an ether group and a methylene group in the side chain are equivalent in influencing the glass transition temperature. We have varied systematically the side chain alkyl group in poly (vinyl alkyl ethers) and evaluated at 3 different temperatures the influence of these variations on the dynamic properties of the vulcanizates of these polymers. The relative position of the curves, relating dynamic resilience to dynamic modulus of these polymers, is generally in the order of their glass transition temperatures. The dynamic mechanical property data on poly (vinyl n-pentyl ether) and poly (vinyl 2-ethylhexyl ether), which have the same glass transition temperature, fall on a common curve characteristic of the temperature of measurement. Apparently, the Tg is a major factor in correlating the dynamic mechanical behavior of these elastomers. The size and shape of the alkyl group appear to be reflected primarily in their effect on the Tg. Polysulfidic crosslinks are not essential for the attainment of high tensile strength in natural rubber vulcanizates cured with a sulfur-diphenylguanidine system. Data for the samples which had lost significant amounts of polysulfidic crosslinks by reaction with triphenylphosphine fitted a curve of tensile strength as a function of 300 per cent modulus for the control samples.

Elaborate fabrication of well-defined side-chain liquid crystalline polyurethane networks with triple-shape memory capacity

2015 ◽  
Vol 3 (25) ◽  
pp. 13435-13444 ◽  
Author(s):  
Zhibin Wen ◽  
Tianhao Zhang ◽  
Yan Hui ◽  
Wanli Wang ◽  
Keke Yang ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Liquid Crystalline ◽  
Memory Capacity ◽  
Side Chain ◽  
Thermal Transition ◽  
Transition Temperatures ◽  
Polyurethane Networks ◽  
Triple Shape Memory

A series of side-chain liquid crystalline polyurethane networks (SCLCPU-Ns) with well-defined architecture are prepared via an elaborate strategy. The SCLCPU-Ns display dual thermal transition temperatures (Tg and Tcl), which can be utilized as Ttrans to trigger the triple shape memory effect.

Helical Sense and Twisting Power in Thermotropic Side–Chain Copolymers

1990 ◽  
Vol 214 ◽  
Author(s):  
Sushil Krishnamurthy ◽  
Shaw H. Chen
Keyword(s):  
Molecular Interactions ◽  
Structural Similarity ◽  
Side Chain ◽  
Backbone Flexibility ◽  
Phenylethyl Alcohol ◽  
Chiral Nematic ◽  
Helical Twisting Power

ABSTRACTThermotropic chiral nematic copolymers containing (S)–(–)–1–phenylethyl alcohol and (R)–(–)–methyl mandelate with methacrylate backbone and those containing (S)–(–)–1–phenylethylamine and cholesterol with acrylate/methacrylate mixed backbone structures have been synthesized and characterized. It is found that the helical sense is dictated by chiral/nematic molecular interactions of a steric nature, and that the helical twisting power (HTP) is favored by the structural similarity between the chiral and nematic components. Furthermore, it is shown that HTP can be optimized with a suitable nematogenic comonomer by regulating the backbone flexibility within the acrylate/methacrylate series, which facilitates supramolecular arrangement without affecting the HTP.

Copolymerization of 2,3:4,5-Di-O-isopropylidene-1-vinylbenzyl-β-D-fructopyranose with styrene: Preparation of polymers containing carbohydrate side chain residues and effect of composition on glass transition temperatures

1978 ◽  
Vol 31 (11) ◽  
pp. 2559 ◽  
Author(s):  
WK Busfield ◽  
FP Franke ◽  
RD Guthrie
Keyword(s):  
Glass Transition ◽  
Specific Rotation ◽  
Solution Viscosity ◽  
Side Chain ◽  
Transition Temperatures ◽  
Radical Initiation ◽  
Glass Transition Temperatures ◽  
A Value ◽  
Free Radical Initiation ◽  
Styrene Content

A range of copolymers of styrene and 2,3:4,5-di-O-isopropylidene-1- vinylbenzyl-β-D-fructopyranose (A) were prepared by free-radical initiation and characterized by i.r., N.M.R., microanalysis and solution viscosity. Reactivity ratios were derived. The specific rotation of the copolymers was linearly related to the molar composition. The glass transition temperatures of the copolymers decreased almost linearly with decreasing styrene content to a value of 73°C for the homopolymer of monomer (A). A method of releasing the isopropylidene blocking groups was developed; the glass transition temperatures of the resultant fructopyranose copolymers increased with decreasing styrene content to a value of 132°C for a copolymer containing 45 mole % styrene.

THE RELAXATION OF TWISTED CHIRAL NEMATIC LIQUID CRYSTALS WITH SIDE-CHAIN POLYMERIC LAYER

2013 ◽  
Vol 27 (22) ◽  
pp. 1350118
Author(s):  
XUAN ZHOU ◽  
ZHIDONG ZHANG
Keyword(s):  
Relaxation Time ◽  
Relative Motion ◽  
Perturbation Analysis ◽  
Dissipation Function ◽  
Side Chain ◽  
Side Chains ◽  
Analysis Method ◽  
Chiral Nematic ◽  
Nematic Director ◽  
Polymeric Layer

A generalized form of surface dissipation function, for the description of the relative motion of the nematic director with respect to the polymer side chains in twisted chiral nematic samples is proposed, and the relaxation time of such samples are investigated, using the perturbation analysis method proposed by Alexe-Ionescu et al. Our results show that the presence of both the surface dissipation and the polymer side chains increase the relaxation time.

ANCHORING OF TWISTED CHIRAL NEMATIC LIQUID CRYSTALS ON A THIN POLYMERIC FILM

2012 ◽  
Vol 26 (10) ◽  
pp. 1250064 ◽  
Author(s):  
XUAN ZHOU ◽  
ZHIDONG ZHANG ◽  
YANJUN ZHANG ◽  
LI XUAN
Keyword(s):  
Liquid Crystals ◽  
Nematic Liquid Crystals ◽  
Side Chain ◽  
Threshold Field ◽  
Side Chains ◽  
Anisotropic Surface ◽  
Chiral Nematic ◽  
Anchoring Energy ◽  
New Variables ◽  
Anisotropic Surface Energy

A generalized form of anisotropic surface energy for the description of twisted chiral nematic samples with side-chain polymeric layers is proposed, and the anchoring properties of such samples are analyzed, using the equivalent anchoring energy method proposed by Alexe-Ionescu et al. Our results give a more general expression for the equivalent anchoring energy, the new variables included in the expression are determined by the anchoring of the side chains and by the sterical interaction of the side chains with the nematic liquid crystals (NLCs). In addition, the coupling of the polymer side chains with the surface, reduces the equivalent anchoring energy as well as the threshold field.

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