@article { ISI:000236150300039, title = {Thermotropic behavior of lithocholic acid derivative linked hydroxyethyl cellulose}, journal = {Journal of Applied Polymer Science}, volume = {100}, number = {3}, year = {2006}, month = {MAY}, pages = {1995-2001}, publisher = {JOHN WILEY \& SONS INC}, type = {Article}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

Various mesogenic lithocholic acid (LA) derivatives [3-acetyl LA (LAAC); 3-propionyl LA (LAP), 3-cinnamoyl LA (LACin); 3-benzoyl LA (LAB), 3-(4-nitrobenzoyl) LA (LANB); and methyl-3-(3-carboxypropionyl) LA, i.e., LA methyl ester monosuccinate (LAMeMS)] were reacted with hydroxyethyl cellulose (HEC) to obtain a series of LA derivatives of HEC. These polymers were characterized by the mesogen content, 1.1, differential scanning calorimetry, and hot-stage coupled polarizing optical microscopy. The degree Of Substitution (DS) ranged from 0.27 to 1.11. Polymers HEC-LAB (DS = 1.11), HEC-LANB (DS = 0.80), HEC-LACin (DS = 0.76), and HEC-LAP (DS = 0.27) exhibited a mesophase on heating whereas HEC-LAB also showed a mesophase on cooling. The other polymers HEC-LAAC (DS = 0.89) and HEC-LAMeMS (DS = 0.36) did not reveal mesophase formation with either heating or cooling. It is observed that the formation of a mesophase is affected by the type of mesogen that is used rather than the mesogen content of the polymer. (c) 2006 Wiley Periodicals, Inc.

}, keywords = {hydroxyethyl cellulose, lithocholic acid, thermotropic}, issn = {0021-8995}, doi = {10.1002/app.22285}, author = {Shaikh, V. A. E. and Maldar, Noormahamad N. and Lonikar, Shrikant Vitthal and Rajan, C. R. and Ponrathnam, S.} } @article {42786, title = {Synthesis and characterization of cholesteric thermotropic liquid crystalline polyesters based on isosorbide}, journal = {Materials Sciences and Applications}, volume = {2}, year = {2011}, month = {OCT}, pages = {1520-1527}, abstract = {

Generally main chain cholesteric thermotropic liquid crystalline polymers are prepared form chiral dia-cid or diol monomer. But these monomers are costly. Isosorbide is chiral cycloaliphatic diol accessible from renewable resources in the form of pure enantiomers. Thus it is used to synthesize main chain cholesteric thermotropic liquid crystalline polymers. Incorporation of phenyl hydroquinone into the backbone of the main chain frustrates chain pack-ing, thus lowering the crystallinity and depressing the melting point below the degradation temperature, also improves the solubility due to disruption of packing and maintains the mechanical and thermal performance. Results: Optical microscopy study reveals that more than 50\% of isosorbide content with phenyl hydroquinone and terephthalic acid showed {\textquotedblleft}yellow iridescent oily streaks{\textquotedblright} with a background of mosaic/marble texture. These are the typical textures of cholesteric liquid crystalline phase. Copolyesters based on phenyl hydroquinone, isosorbide and terephthalic acid are soluble in aprotic solvents like N,N-dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N-methyl-2-pyrrolidone (NMP). Solubility increases with the content of isosorbide percent. Thermal stabil-ity of all copolyesters was more than 300oC on the basis of 10 wt\% loss. Conclusions: It was found that main chain cholesteric thermotropic liquid crystalline polymers can be prepared form chiral cycloaliphatic diol such as isosorbide. Main chain cholesteric thermotropic liquid crystalline polyesters are prepared from phenyl hydroquinone, isosorbide and terephthalic acid showed thermal stability more than 300oC. Main chain cholesteric thermotropic liquid crystalline polymers are soluble in aprotic solvents like DMAC, DMSO, DMF and NMP

}, keywords = {Cholesteric, Crystallinity, differential scanning calorimetry, Inherent Viscosity, Liquid Crystalline Polymers, Optical Microscopy, Solubility and Solution Polycondensation, Thermo Gravimetric Analysis, thermotropic, Wide Angle X-Ray Diffraction}, doi = {10.4236/msa.2011.210205}, author = {Chavan, Nayaku} } @article { ISI:000363005100025, title = {Thermotropic liquid crystalline polyesters derived from bis-(4-hydroxybenzoyloxy)-2-methyl-1,4-benzene and aliphatic dicarboxylic acid chlorides}, journal = {Bulletin of Materials Science}, volume = {38}, number = {5}, year = {2015}, month = {SEP}, pages = {1301-1308}, publisher = {INDIAN ACAD SCIENCES}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

A series of thermotropic liquid crystalline polyesters derived from bis-(4-hydroxybenzoyloxy)-2-methyl-1,4-benzene(BHBOMB) and aliphatic dicarboxylic acid chlorides were investigated. All these polyesters were synthesized by interfacial polycondensation method and characterized by differential scanning calorimetry and wide-angle X-ray diffractometer. These polyesters consist of BHBOMB as a mesogenic diol and aliphatic diacid chlorides were used as flexible spacers. The length of oligomethylene units in polymer was varied from the trimethylene to the dodecamethylene groups. The transition temperatures and thermodynamic properties were studied for all these polymers. All these polyesters were soluble in chlorinated solvents such as chloroform, dichloromethane, dichloroethane, etc. More importantly, all these polyesters exhibited very large mesophase stability.

}, keywords = {dicarboxylic acid chloride, interfacial polycondensation, Liquid crystalline polyesters, rigid diol, thermotropic}, issn = {0250-4707}, author = {Mulani, Khudbudin Baban and Momin, Mohasin Shamshuddin and Ganjave, Nitin V. and Chavan, Nayaku} }