(654g) An Efficient Process for the Cu(0)-Catalyzed Controlled Radical Synthesis and Subsequent Chain Extension of Poly(Methyl Acrylate) Macroinitiator

Copper mediated polymerization is used to produce poly(methyl acrylate) with an average degree of polymerization of 10 (P(MA)₁₀) and narrow dispersity in both batch and continuous tubular reactors at ambient temperature. The resulting polymer solution could be stored for over a week while maintaining excellent activity as a macroinitiator for the further growth of poly(methyl acrylate) chains in both batch and semi-batch reactor systems. Low dispersities were maintained during the chain-extensions, conducted at ambient temperature without addition of further copper to the system. The polymerizations were conducted in propylene glycol methyl ether, a common industrial solvent, with low levels of ascorbic acid added as a reducing agent for chain extension; 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. Semi-batch chain extensions of P(MA)₁₀ with butyl acrylate, poly(ethylene glycol) methyl ether acrylate (PEGMEA), and butyl methacrylate as well as the ability to synthesis tri-block polymer were also demonstrated, as was the synthesis and subsequent chain extension of (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.