Polyimides with cyclohexyl‐substituted indan groups in the main chain

Abstract

AbstractA diamine monomer containing the 1,3‐biscyclohexyl‐1‐methylindan group was prepared, starting from cyclohexyl phenyl ketone in four steps. This monomer was reacted with six different dianhydrides (pyromellitic dianhydride, 3,4:3′,4′‐biphenyltetracarboxylic dianhydride, 3,4:3′,4′‐benzophenonetetracarboxylic dianhydride, 4,4′‐oxydiphthalic anhydride, 4,4′‐sulfonyldiphthalic anhydride, 4,4′‐perfluoroisopropylidenediphthalic anhydride) to give the corresponding polyimides via the poly(amic acid) precursors and thermal imidization. All of these polyimides were soluble at least in N‐methyl‐2‐pyrrolidone (NMP) at elevated temperatures, some were soluble in NMP and chlorinated hydrocarbons even at room temperature. The polymers were characterized by nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and dynamic thermogravimetry. All polyimides proved to be amorphous with glass transition temperatures in the range between 261°C and 295°C depending on the nature of the dianhydride moiety. Their decomposition proceeds in two steps, starting at 400°C probably with loss of the cyclohexyl substituents.