Synthesis of Silicone Resins Containing Polystyrene and Poly(t-butyl acrylate) Grafts using ATRP and “Click” Chemistry

摘要

Silicones are very versatile for various applications such as coatings, encapsulatants, elastomers and various other applications. Unique properties of polyorganosiloxanes include excellent low temperature flexibility, good thermal and oxidative stability, ozone and UV resistance, high gas permeability, excellent electrical and physiological inertness or biocompatibility. Tethering of the silicones using various functionalities such as hydrophilic and hydrophobic moieties, improves the properties of silicones. In our group, silicones and modified silicones have been used for marine coatings applications. Atom Transfer Radical Polymerization (ATRP) facilitates the synthesis of a broad variety of polymeric materials with predetermined molecular weights (Mn) and polydispersities (PDI) and a high degree of chain end functionalization. There has been recent interest in low molecular weight (Mn) block copolymers containing t-butyl acrylate (t- BA) or acrylic acid and styrene for their commercial applications such as amphiphilic block and marine coatings. Synthesis of homo blocks and block copolymers of t-BA and styrene have been reported in the literature by ATRP, and RAFT and nitroxide-mediated free radical polymerizations. Efficient and specific reactions are desirable for post-polymerization or polymer modification reactions to be highly successful and widely applicable. Recently, Sharpless et al. have coined the term “click” chemistry to describe a set of highly efficient and specific organic reactions that can be conducted in a range of environments under relatively non stringent reaction conditions. There are large numbers of possible functional groups and end functional polymer can be made via click chemistry. The combination of ATRP and post-polymerization modification by click chemistry is a promising strategy to synthesize various functionalized polymers. Herein, we report and demonstrate the modification of silicone polymers via ATRP and click chemistry.