Polymerizability and chiroptical properties of the N-substituted maleimide bearing L-phenylalanine alkyl ester

Four types of N-maleoyl-L-phenylalanine alkyl ester (RPAM) polymers were synthesized from maleic anhydride, L-phenylalanine and the corresponding alcohols, i.e., ethyl, butyl, dodecyl, or benzyl alcohol. Radical and anionic polymerizations were performed. Bulkiness of the ester group decreased polymerizability. However, bulkiness was Favorable to asymmetric induction into the homopolymer main chain. In addition, polymers obtained by radical polymerizations had regular main chain structures smaller than those obtained by anionic polymerizations. The difference of the regularity caused different chiroptical properties of the polymers. Radical copolymerizations with styrene (ST) or methyl methacrylate (MMA) were performed and monomer reactivity ratios and Alfrey-Price Q-e were determined. Chiroptical properties of the copolymers were significantly influenced by the ST or MMA co-unit. Bulkiness of the ester group hardly influenced chiroptical properties of the copolymers.