Triblock copolymers based on styrene and n-butyl acrylate by nitroxide-mediated radical polymerization: Problems and solutions

摘要

Controlled radical polymerization (CRP) has been experiencing tremendous developments of late, with spectacular achievements in macromolecular engineering. Well-defined star polymers as well as block copolymers can be obtained using miscellaneous CRP methods. This paper is the second of a series devoted to the synthesis of triblock copolymers by nitroxide-mediated polymerization, using a P-hydrogen containing phosphonylated nitroxide (SG1) as stable radical. It focuses on the problems associated with the sequential polymerization of styrene and n-butyl acrylate while synthesizing poly(styrene-b-n-butyl acrylate-b-styrene) copolymers from SG1-based macromolecular alkoxyamines. In particular, it discloses how the blocking efficiency can be improved when growing the second poly(n-butyl acrylate) (PBuA) block from the first polystyrene (PS) block. The proportion of dead chains that contaminate such triblock samples is also evaluated. [References: 11]