Cholesteric polycarbonates

Cholesteric polycarbonates 72 derived from 1 and 2,5-bis(4 -hydroxybenzyli-dene)cyclopentanone were also described [58]. 

Cholesteric polycarbonates derived from DAS bis(phenyl carbonate), methyl hydroquinone, and 4,4 -dihydro-biphenyl were better obtained by polycondensation in pyridine-containing organic solvents, as reported by Kricheldorf et al. [39]. Trichloromethylchloroformate (TCF) was successfully used for all these polycondensations. The use of solid TCF is advantageous over phosgene because it is easy to apply in stoichiometric amounts, easy to store, and commercially available. 

Cholesteric polycarbonates derived from DAS and 2,5-bis(4 -hydroxybenzylidene)cyclopentanone have also been described [41]. 

Kricheldorf H.R., Sun S.J., Gerken A., Ch. Chang T., Polymers of carbonic add 22. Cholesteric polycarbonates derived from (S)-[(2-methylbutyl)thio]hydroquinone or isosorbide. Macromolecules, 29, 1996, 8077—8082. 

Kricheldorf H.R., Sun Sh.J., Chen Ch.R, Chang T.Ch., Polymers of carbonic acid. XXIV. Photoreactive, nematic or cholesteric polycarbonates derived from hydroquinone-4-hydroxybenzoate 4,4 -dihydroxychtilcone and isosorbide, J. Polym. Sci. Part A Polym. Chem., 35, 1997, 1611-1619. 

Sun S.J., Schwarz G., Kricheldorf H.R., Ch. Chang T., New polymers of cabonic acid. XXV. Photoreactive cholesteric polycarbonates derived from 2,5-bis(4 -hydroxybenzylidene)cyclopentanone and isosorbide, J. Polym. ScL Part A Polym. 

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