NIR photothermal activation in epoxy/thiol polymerization

Abstract

Epoxy resins are widely employed in coatings and adhesives due to their mechanical strength, thermal stability, and adhesion properties. In recent years, the thiol–epoxy “click” reaction has emerged as a prominent approach in the field of photocuring, offering mild reaction conditions, high efficiency, and oxygen insensitivity. However, conventional UV-curing strategies are limited by shallow penetration depths and potential safety concerns. To overcome these limitations, we explored a near-infrared (NIR)-induced photothermal strategy to trigger epoxy/thiol polyaddition reactions. In this work, various thiol-based crosslinkers and thermal initiators were evaluated to optimize the formulation. Polymerization kinetics were monitored via Real-Time Fourier Transform Infrared Spectroscopy (RT-FTIR), and the photothermal effect of the different systems was characterized to assess the heat generation and curing efficiency. This study highlights the potential of NIR-activated thiol–epoxy systems as a safe and effective alternative for deep and rapid curing in advanced material applications.