Polymer networks, which include everyday materials such as tires and contact lenses, play an essential role in modern life due to their ability to deform and recover. However, these materials are prone to cracking and fatigue over time, ultimately leading to failure and the release of microplastic and microrubber particles into the environment. This collaborative research project aims to advance the fundamental understanding of how polymer networks break, with the goal of designing stronger and longer-lasting materials. By gaining insight into how energy is stored, transferred, and dissipated during fracture, this work can support national efforts to reduce plastic pollution and improve the durability of consumer and industrial products. The project also includes integrated efforts in graduate and undergraduate education, outreach to K-12 students, and cross-institutional collaboration between researchers at two universities. These efforts will help train the next generation of scientists and engineers in a critical area of mechanics and materials. This project will formulate and validate a new molecular-level model to explain the intrinsic fracture energy of polymer networks. Unlike traditional models that focus solely on the energy needed to break individual polymer chains, this research will incorporate the role of surrounding material structure, including how energy is dissipated throughout the network and how features such as topology and chain entanglements affect fr