Functionalization of polyurethanes by incorporation of alkyne side-groups to oligodiols and subsequent thiol–yne post-modification

A versatile and upscalable method for the synthesis of polyurethanes (PUs) bearing pendant functionalities at the hard–soft segment interface from easily accessible commercial oligodiols is described. Reactive alkyne groups were introduced to polytetrahydrofuran (PTHF), poly(ε-caprolactone) (PCL) and polydimethylsiloxane (PDMS) diols by cationic ring-opening polymerization of glycidyl propargyl ether using these oligodiols as macroinitiators. The resulting oligodiols, with alkyne side groups located at both chain ends, were subsequently reacted with 1,4-butanediol and hexamethylene diisocyanate for the synthesis of PUs, containing several pendant alkyne groups between the soft and hard segments. The functionalized PUs based on different soft segments (PTHF, PCL or PDMS) have been further modified via metal-free thiol–yne chemistry. Proper reaction conditions were found for quantitative radical thiol–yne coupling reactions with benzyl mercaptan and thioglycerol.