Diisocyanate route as a convenient method for the preparation of novel optically active poly(amide–imide)s based on N-trimellitylimido- S-valine

Abstract

A new class of optically active poly(amide–imide)s based on an α-amino acid was synthesized via direct polycondensation reaction of different diisocyanates with a chiral diacid monomer. The step-growth polymerization reactions of N-trimellitylimido- S-valine (TISV) ( 1) with 4,4′-methylene-bis(4-phenylisocyanate) (MDI) ( 2) was performed under microwave irradiation, as well as solution polymerization under graduate heating and reflux conditions. The optimized polymerization conditions for each method were performed with tolylene-2,4-diisocyanate (TDI) ( 3), hexamethylene diisocyanate (HDI) ( 4), and isophorone diisocyanate (IPDI) ( 5) to produce optically active poly(amide–imide)s via diisocyanate route. The resulting polymers have inherent viscosities in the range of 0.02–1.10 dL/g. Decomposition temperatures for 5% weight loss ( T 5) occurred above 300 °C (by TGA) in nitrogen atmospheres. These polymers are optically active, thermally stable and soluble in amide-type solvents. Some structural characterization and physical properties of this new optically active poly(amide–imide)s are reported.