Synthesis of alkynyl-functionalized linear and star polyethers by aluminium-catalyzed copolymerization of glycidyl 3-butynyl ether with epichlorohydrin and ethylene oxide†
The sequential and simultaneous copolymerization of glycidyl 3-butynyl ether (GBE) with ethylene oxide (EO) and epichlorohydrin (ECH) by an aluminium-based catalyst i-Bu3Al/H3PO4/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) has afforded for the first time a new family of alkynyl-functionalized linear and star polyethers. The linear GBE–EO, GBE–ECH and GBE–EO–ECH block copolymers with different block structures were conveniently obtained by sequential copolymerization of GBE with EO and ECH. The linear GBE–EO, GBE–ECH, and GBE–EO–ECH statistical copolymers with a slight gradient structure and controllable compositions and molecular weights were conveniently obtained by simultaneous copolymerization of GBE with EO and ECH. The alkynyl groups could be incorporated into various linear polyethers quantitatively in block and slight gradient form. On the basis of the living/controlled characteristic of the ring-opening polymerization of epoxide monomers by i-Bu3Al/H3PO4/DBU, star alkynyl-functionalized polyethers with a well-defined arm length and arm number were successfully synthesized in 100% yield through the “arm-first” strategy with 3-bis(oxiran-2-ylmethoxy)benzene as cross-linkers.