An Efficient Process for the Cu(0)-Catalyzed Controlled Radical Synthesis and Subsequent Chain Extension of Poly(Methyl Acrylate) Macroinitiator
Shirali zadeh, Niloofar
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Copper mediated polymerization is used to produce poly(methyl acrylate) with an average degree of polymerization of 10 (P(MA)10) and narrow distribution 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.