Synthesis and properties of water-soluble light-sensitive copolyamides☆

A series of light-sensitive water-soluble copolyamides with terminal carboxyl, amine, and photoinitiating (benzoin) fragments in the macro-chain are synthesized by polycondensational telomerization in a melt of a mixture of a salt of ethylene diglycol and piperazine + adipic acid and hexamethylenediamine at various benzoin concentrations. It is shown by means of model reactions of the interaction of benzoin with stearic acid and hexamethylenediamine that in the system under study benzoin, as a typical ketoalcohol, reacts competitively with the carboxyl and amine groups of the copolyamide. The change in [η] during synthesis is extremal in character. Moreover, with all the benzoin concentrations studied, i.e. 1–25 mol.%, the maximum [η]max for the copolyamide is attained after ∼ 3 h, after which a sharp decrease in the MM of the polymer is observed because of degradation.