Synthesis and characterization of the ABA-type poly(ester-ether-ester) block copolymers

Abstract

Polyethylene glycol with average molar mass of 1,450 Da (PEG-1450) was treated with equivalent amount of sodium hydride to convert hydroxy groups to sodium alkoxide. Assuming the PEG oligomer with alkoxy end-groups as a macroinitiator, anionic ring-opening polymerization of some lactones (beta-propiolactone, alpha-methyl-beta-propiolactone, delta-valerolactone and epsilon-caprolactone) with different ring sizes were performed to obtain the ABA-type poly(ester-ether-ester) block copolymers. Copolymers with various compositions were obtained with high yields. Spectroscopic and thermal characterization of the copolymers were performed by using DSC, TGA, FT-IR, and H-1-NMR spectroscopy. Formation of the block copolymers and their mass distributions were determined by MALDI mass spectrometry. Structural analyses of the copolymers revealed that chain extensions increased in order of alpha-methyl-beta-propiolactone, beta-propiolactone, delta-valerolactone and epsilon-caprolactone.