Synthesis of Ultrahigh Molecular Weight Poly(Carboxylic Acids) via Aqueous Triplet-Enhanced Photoiniferter Polymerization.

Achieving precise control over the synthesis of high molecular weight poly(carboxylic acids) remains a formidable challenge. Herein, we report the use of triplet-enhanced photoiniferter polymerization (TEPP) to address this limitation. Aqueous TEPP of acrylic acid exhibits rapid kinetics, strict temporal control, high end-group fidelity, and excellent oxygen tolerance under mild blue light irradiation at room temperature, yielding poly(acrylic acid) with molecular weights up to 1370 kg mol-1 (Đ = 1.10). Rheological studies reveal a pronounced influence of molecular weight on the chain dynamics and viscoelastic properties of the polymer solutions. Furthermore, this TEPP strategy is extended to the precipitation polymerization of 2-carboxyethyl acrylate, demonstrating its synthetic versatility and broad applicability.