Facile synthesis of graft copolymers of controlled architecture. Copolymerization of fluorinated and non-fluorinated poly(dimethylsiloxane) macromonomers with trialkylsilyl methacrylates using RAFT polymerization

Abstract

The synthesis and spectroscopic characterization of a new family of statistical and diblock graft copolymers is described. A series of linear graft copolymers have been synthesized by RAFT polymerization of trialkylsilyl methacrylates (TASMA) with two types of commercially available methacryloxypropyl-substituted polydimethylsiloxanes (PDMSMA) as macromonomers. The resulting poly(PDMSMA)-g-poly(TASMA) graft copolymers exhibited various branching distributions depending on the reactivity of the monomers used. We were able to control graft densities of the copolymers by using two TASMA monomers with substantially different reactivities, e.g. tert-butyldimethylsilyl methacrylate (TBDMSMA) vs. tri-isopropylsilyl methacrylate (TIPSMA). While TBDMSMA-based statistical copolymers were heterogeneously branched their counterparts (i.e. TIPSMA-based statistical copolymers) had PDMS side chains more homogeneously distributed along their backbones. The monomer reactivity ratios (r) were determined by using the Jaacks method. In addition, diblock copolymers of PDMSMA and TASMA were synthesized by chain extension of a macro RAFT agent easily available in one synthetic step from PDMS-containing starting materials. Copolymers with well-controlled molar masses and low dispersities were obtained, indicating relatively fast initiation and minimal side reactions. The surface energy and erosion properties in these copolymers were investigated in artificial seawater in order to apply them as binders in self-polishing/fouling release hybrid antifouling coatings.