Photoinduced sequence-control via one pot living radical polymerization of acrylates

Abstract

The ability to regulate the activation and deactivation steps via an external stimulus has always been a challenge in polymer chemistry. In an ideal photo-mediated system, whereby high monomer conversion and excellent end group fidelity can be maintained, precise control over the polymer composition and microstructure would be a significant breakthrough. Herein, we report, a versatile, simple and inexpensive method that allows for the synthesis of sequence-controlled multiblock copolymers in a one pot polymerization reaction at ambient temperature. In the absence of a conventional photoredox catalyst and dye-sensitisers, low concentrations of CuBr₂ in synergy with Me₆-Tren mediate acrylic block copolymerization under UV irradiation (λ_max ≈ 360 nm). Four different acrylate monomers were alternated in various combinations within the polymer composition illustrating the potential of the technique. Narrow disperse undecablock copolymers were obtained (Đ < 1.2) with quantitative conversion achieved between the iterative monomer additions. The effect of the chain length was investigated allowing for higher molecular weight multiblock copolymers to be obtained. This approach offers a versatile and inexpensive platform for the preparation of high-order multiblock functional materials with additional applications arising from the precise spatiotemporal “on/off” control and resolution when desired.