Synthesis and characterization of poly(t‐butyl methacrylate‐b‐isoprene‐b‐t‐butyl methacrylate) block copolymers by anionic techniques

Poly(t‐butyl methacrylate‐b‐isoprene‐b‐t‐butyl methacrylate) block copolymers have been synthesized in a controlled manner by anionic techniques. The block copolymers demonstrated predictable chemical composition and stereochemistry, and narrow molecular weight distributions. The addition of a polar solvent was required after complete conversion of the diene block in order to preserve the high 1,4 microstructure of the diene phase and to facilitate the efficient crossover to the poly(t‐butyl methacrylate) lithium enolate. Thermomechanical analysis (TMA) of the triblock copolymers demonstrated a microphase separated morphology. The glass transition temperatures of the diene phase and acrylic phase were approximately −70 and 120°C, respectively. Cast films of the block copolymers from polar and nonpolar solvents were optically clear and elastic.