Synthesis and properties of polydimethylsiloxane‐containing block copolymers via living radical polymerization

Polydimethylsiloxane (PDMS) block copolymers were synthesized by using PDMS macroinitiators with copper‐mediated living radical polymerization. Diamino PDMS led to initiators that gave ABA block copolymers, but there was low initiator efficiency and molecular weights are somewhat uncontrolled. The use of mono‐ and difunctional carbinol–hydroxyl functional initiators led to AB and ABA block copolymers with narrow polydispersity indices (PDIs) and controlled number‐average molecular weights (Mn's). Polymerization with methyl methacrylate (MMA) and 2‐dimethylaminoethyl methacrylate (DMAEMA) was discovered with a range of molecular weights produced. Polymerizations proceeded with excellent first‐order kinetics indicative of living polymerization. ABA block copolymers with MMA were prepared with between 28 and 84 wt % poly(methyl methacrylate) with Mn's between 7.6 and 35 K (PDI <1.30), which show thermal transitions characteristic of block copolymers. ABA block copolymers with DMAEMA led to amphiphilic block copolymers with Mn's between 9.5 and 45.7 K (PDIs of 1.25–1.70), which formed aggregates in solution with a critical micelle concentration of 0.1 g dm−3 as determined by pyrene fluorimetry experiments. Monocarbinol functional PDMS gave AB block copolymers with both MMA and DMAEMA.