An efficient process for the Cu(0)-mediated synthesis and subsequent chain extension of poly(methyl acrylate) macroinitiator

Abstract

Low dispersity poly(methyl acrylate) with a target degree of polymerization of 10 (poly(MA)₁₀) was produced in both batch and a continuous tubular reactor at room temperature using Cu(0) catalysis. The resulting polymer solution could be stored for over a week while maintaining excellent activity as a macroinitiator for the further growth of poly(acrylate) chains in both batch and semi-batch reactor systems. The chain-extensions were done without addition of further copper to the system using ascorbic acid as a reducing agent; the best performance (>90% conversion with excellent control) was achieved when a fraction of the ascorbic acid was added to the reactor at the start of reaction, with the rest fed in a semi-batch fashion along with monomer over three hours. Semi-batch chain extensions of poly(MA)₁₀ with butyl acrylate and poly(ethylene glycol) methyl ether acrylate (PEGMEA) were conducted, and a tri-block polymer was also synthesized. The feasibility of applying this procedure to other monomers was demonstrated through the synthesis and chain extension of poly(PEGMEA)₁₀. The combination of the tubular reactor to produce macroinitiator and subsequent semi-batch chain extension is proposed as a versatile process to efficiently produce block copolymers at an industrial scale.