Accessing broader vinyl ether scope for sequential cationic-anionic block copolymers

Abstract

The combination of multiple polymerization mechansisms in a single polymer chain allows for the synthesis of block copolymers with blocks of significantly different chemical structures. Previously, the combination of cationic polymerization of vinyl ethers and anionic polymerization of thiiranes was enabled through the use of a thiocarbonyl thio universal mediator, albiet limited in scope to just ethyl vinyl ether for the cationic block. Herein, we utilize a Brønsted acid-catalyzed reversible-deactivation cationic polymerization and/or modified thioacyl anionic group transfer polymerization conditions to successfully chain extend six additional poly(vinyl ether)s – dramatically increasing the scope of monomers supported. Thermal analyses reveal a large range of glass transition temperatures now available (−58 to 74 °C), including those significantly above room temperature which were not accessible using the previous method.