Theoretical and numerical modeling of the radical photo-crosslinking process in semi-crystalline polymer networks

Radical photo-crosslinking is a widely used strategy for the fabrication of polymer networks, as it enables efficient and spatially-controllable formation of chemically-crosslinked architectures. The performance of photo-crosslinked networks is strongly governed by the efficiency and uniformity of the crosslinking process. Despite its widespread use, only limited theoretical frameworks are available to describe the radical photo-crosslinking process in semi-crystalline polymer networks in a unified and predictive manner. In this work, we propose a framework to describe light-induced radical crosslinking in semi-crystalline polymer networks. The model combines a three-dimensional formulation of the Beer–Lambert law for radiative transfer with mass balance equations governing photo-initiator activation, radical generation, and crosslinking reactions. Reaction kinetics are described through the law of mass action, finally enabling a quantitative prediction of network evolution as a function of processing parameters. The framework is validated on poly(ɛ-caprolactone)-based networks, which are widely employed as shape memory polymers. An experimental campaign is conducted in which light intensity, exposure time, and processing temperature are systematically varied. Model predictions are compared against experimentally measured indicators of crosslinking efficiency, demonstrating the capability of the framework to capture the influence of photo-crosslinking conditions on network formation. The proposed approach provides a novel theoretical tool to rationalize and optimize radical photo-crosslinking in semi-crystalline polymer networks and establishes a foundation for future coupling with thermo-mechanical and shape memory constitutive models, with implications for the design of high-performance polymer systems.