Consequences of Chemical Modification on Optical and Solution Properties of Rodlike Polyamides

Rodlike polyamides were substituted to 50–55% on the nitrogen atom of the amide group with benzyl, 1-naphthylmethyl, and 4-(1,3,6,8-tetrabromo-9-carbazolyl)-1-butyl groups using a standard literature procedure. The resulting polymers exhibit significantly lower isotropic refractive indices and enhanced solubility. Polymers composed of the isophthaloyl moiety, with or without N-substitution, also exhibit lower refractive indices and enhanced solubility when compared to their rodlike analogs. These differences in properties are due to a great extent to the large difference in conformational rigidity between the two polymer types.