Anionic ring-opening polymerization following atom transfer radical polymerization: Poly(glycidyl methacrylate-g-dimethylsiloxane) obtained by "grafting from" strategy

The reactivity of pendant epoxide groups of poly(glycidyl methacrylate) (PGMA) in reaction pathways devised under the concepts of anionic ring-opening polymerization (AROP) to yield poly(glycidyl methacrylate-g-dimethylsiloxane) [poly(GMA-g-DMS)] copolymers is reported in this study. Three grafting approaches were undertaken starting with PGMA synthesized by atom transfer radical polymerization (ATRP). While living anionic poly(dimethylsiloxane) chains could not be coupled to PGMA backbone via grafting onto mechanism, the grafting from route, which involved first the reaction of epoxide moieties of PGMA backbone with sec-Bu-Li+ to yield poly(GMA-Li+) and then the anionic polymerization of hexamethylcyclotrisiloxane monomer, proved successful and consistent. SEC, NMR, FTIR, DSC, and TGA results indicated that up to six units of DMS could be incorporated per epoxide site, resulting in poly(GMA-g-DMS) amorphous copolymers. The reaction pathway reported in this work offers a new concept on the synthesis of glycidyl/siloxane based copolymers with a wide range of commercial applications already reported in literature.Highlights A novel synthesis approach to poly(GMA-g-DMS) hybrid graft copolymers. Reaction of epoxide rings in the PGMA backbone with sec-Bu-Li+ yields P(GMA-Li+). Anionic polymerization of hexamethylcyclotrisiloxane from P(GMA-Li+) is successful. Unsuccessful attack of living PDMS-Li+ chains to pendant oxirane groups of PGMA. Addition of a polarizing agent (LiCl) has no effect on the reactive ion-pairs.