Synthesis of polymers from α-amino acids by polyaddition

Abstract

Novel network polymer films were prepared from glutamic acid diethylester hydrochloride (2Et-Glu·HCl) and hexamethylene diisocyanate (film A) or lysine triisocyanate (film B). Prepolymers prepared by melt polyaddition were cast from dimethylformamide solution and then post-polymerized at 240° for various times. The resulting films were slightly yellow, transparent, flexible and insoluble in organic solvents. Infrared spectra showed that the post-polymerization reached equilibrium after 24–36 hr. Two broad but distinct peaks were observed in the X-ray diffraction curves for film A, suggesting the formation of some ordered structure. Heat distortion temperature measured by TMA was in good agreement with glass transition temperature measured by DTA; both values increased with increasing post-polymerization time and leveled out after 24–36 hr. The tensile strength, elongation and Young's modulus also increased with increasing post-polymerization time. However, prolonged post-polymerization caused decrease of tensile strength. Film B showed higher thermal stability and water absorption and lower alkali resistance than film A.