Near-Infrared Photothermal Polymerization of Thioctic Acid Triggered by Polyoxometalate Crosslinker

The monomer conversion rate of thioctic acid (TA) and the cross-linking degree of polymer chains significantly influence the performance of materials, making them important research topics. Herein, by selecting a reduced polyoxometalate complex modified with 1-allylpyridinium cations, which exhibits strong near-infrared (NIR) light absorption capability, as both photothermal agent and cross-linking agent, the polymerization of TA is successfully achieved under NIR light irradiation. The incorporation of photothermal agents results in their multiple dispersion throughout the polymerization matrix, facilitating uniform internal heat generation and inside-out thermal diffusion. This mechanism significantly shortens the heat conduction pathway and effectively mitigates the inhomogeneous polymerization typically caused by temperature gradients inherent in conventional heating methods. Moreover, the C─S bonds formed via the reaction between the C═C groups and the disulfide linkages of TA not only suppress depolymerization but also serve as robust anchoring sites within the polymer network. By tuning the monomer composition, TA-based adhesives and elastomers are successfully fabricated, exhibiting excellent re-processability through NIR-triggered remelting or repair. The NIR-light-regulated polymerization approach offers distinct advantages, including operational simplicity, rapid response, and spatiotemporal control, thereby presenting a promising strategy for the synthesis of high-performance TA-based polymers.