Synthesis and characterization of the ABA-type poly(ester-ether-ester) block copolymers
Efkan Çatıker, Temel Öztürk, Mehmet Atakay, Bekir Salih
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 (β-propiolactone, α-methyl-β-propiolactone, δ-valerolactone and ε-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 1H-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 α-methyl-β-propiolactone, β-propiolactone, δ-valerolactone and ε-caprolactone.