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

Controlled radical polymerization (CRP) has been experiencing tremendous de velopments of late, with spectacular achievements in macromolecular enginee ring. Well-defined star polymers as well as block copolymers can be obtaine d using miscellaneous CRP methods. This paper is the second of a series dev oted to the synthesis of triblock copolymers by nitroxide-mediated polymeri zation, using a P-hydrogen containing phosphonylated nitroxide (SG1) as sta ble radical. It focuses on the problems associated with the sequential poly merization of styrene and n-butyl acrylate while synthesizing poly(styrene- b-n-butyl acrylate-b-styrene) copolymers from SG1-based macromolecular alko xyamines. In particular, it discloses how the blocking efficiency can be im proved when growing the second poly(n-butyl acrylate) (PBuA) block from the first polystyrene (PS) block. The proportion of dead chains that contamina te such triblock samples is also evaluated.