Synthesis of Block Copolymers by Group Transfer Polymerization, GTP

Synthesis of Block Copolymers by Group Transfer Polymerization, GTP 

The controlled polymerization of (meth)acrylates was achieved by anionic polymerization. However, special bulky initiators and very low temperatures (- 78 °C) must be employed in order to avoid side reactions. An alternative procedure for achieving the same results by conducting the polymerization at room temperature was proposed by Webster and Sogah [84]. The technique, called group transfer polymerization, involves a catalyzed silicon-mediated sequential Michael addition of a, fl-unsaluraled esters using silyl ketene acetals as initiators. Nucleophihc (anionic) or Lewis acid catalysts are necessary for the polymerization. Nucleophihc catalysts activate the initiator and are usually employed for the polymerization of methacrylates, whereas Lewis acids activate the monomer and are more suitable for the polymerization of acrylates [85,86]. 

and BAG triblock terpolymers, where A is PMMA, B is PDMAEMA, and C is poly[hexa(ethylene glycol)methacrylate], PHEGMA, were synthesized via GTP and sequential monomer addition [89]. The polymerizations were conducted in THF using MTS and TBABB as the initiator 

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