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.