| Abstract: | Four series of new poly(β-aminoester)s based on different mesogenic units and amino spacers were prepared and their properties examined. The polymers were obtained by a Michael-type polyaddition reaction of the diamines piperazine ( 5a ), 2-methylpiperazine ( 5b ), N,N′-dimethylhexamethylenediamine ( 5c ), and 4,4′-trimethylenedipiperidine ( 5d ) to diacrylates containing the anisotropic group, trans-4,4′-vinylenedi-p-phenylene diacrylate ( 1 ), 4-(4-acryloyloxybenzylideneamino)phenyl acrylate ( 2 ), 4,4′-diphenylylene diacrylate ( 3 ), and 4,4′-azoxydi-p-phenylene diacrylate ( 4 ). The mesophase behaviour of the resulting polymers 6–9 was strongly influenced by the nature of both the anisotropic and spacer groups. The 4,4′-azoxydi-p-phenylene unit appeared to be the most efficient in promoting liquid crystal properties, whereas no mesophases could be observed in polymers incorporating the 4,4′-biphenylylene unit. Doping of poly(β-aminoester)s, based on 4,4′-azoxydi-p-phenylene units, with a low-molar-mass cholesterogen allowed to obtain cholesteric structures extending over wide ranges of temperature. The molecular weight of the polymers was found to play a role in determining thermotropic mesomorphism by affecting the melting temperature of the polymer. In this context, some non-macromolecular model compounds were analyzed in respect of their thermal behaviour. |
