Selective ring-opening polymerization of glycidyl esters: a versatile synthetic platform for glycerol-based (co)polyethers

Linear polyglycerols are highly valued for their excellent hydrophilicity and biocompatibility as well as their multihydroxy nature. We report here a convenient route for the controlled synthesis of polyglycerols through ring-opening polymerization (ROP) of commercialized glycidyl butyrates (GBs). Starting from enantiopure GBs, well-defined poly(glycidyl ester)s with controlled molar mass and stereoregularity are achieved thanks to the chemoselectivity of the bicomponent metal-free catalyst that prevents both transesterification and epimerization. The pendant butyrate groups are readily cleaved by organobase-catalyzed methanolysis, yielding linear polyglycerols that inherit isotacticity and regioregularity from the parent polymers. Copolymerization of SGB and propylene oxide occurs in a random manner resulting in a series of narrowly distributed copolyethers with a precisely regulated number of pendant hydroxyl groups to afford tunable aqueous thermosensitivity. The method is further extended to construct polyglycerol-based amphiphilic and double-hydrophilic copolyethers by block copolymerization of RGB with tert-butyl glycidyl ether and ethylene oxide, respectively.

Automated summary

In this study, linear polyglycerols were synthesized using commercial glycidyl butyrates, and the control over the molar mass and stereoregularity of the polymers was achieved. The copolymerization of glycidyl butyrates with other monomers resulted in copolyethers with different aqueous thermosensitivity.