Synthesis and characterization of novel barbwire-like graft polymers poly(ethylene oxide)-g-poly(ε-caprolactone)4 by the ‘grafting from’ strategy

Abstract

Novel barbwire-like graft polymers PEO-g-PCL₄ were synthesized by combination of ring opening polymerization (ROP) and Glaser coupling with thiol–yne addition reaction via the “grafting from” strategy. Typically, the precursor (PEO-diyne-PEO)_s of high molecular weight was obtained by Glaser coupling of alkyne-PEO-alkyne, which was prepared by modification of HO-PEO-OH with propargyl bromide. After the diyne groups on PEO were transferred into hydroxyl groups by efficient thiol–yne addition reaction with mercaptoethanol, the macroinitiator [PEO-(OH)₄-PEO]_s was obtained and the graft polymers PEO-g-PCL₄ were synthesized by ROP of ε-caprolactone monomers. The structure of graft polymers was confirmed by GPC, MALDI-TOF MS, ¹H NMR, and TGA measurements in detail, and the crystallization behavior of graft polymers was also comprehensively investigated using DSC, WAXD, and POM instruments.