Discovering polyimides and their composites with targeted mechanical properties through explainable machine learning

Polyimides (PIs) are widely used in industries for their exceptional mechanical properties and thermal resilience. Despite their benefits, the traditional development process for PIs is time-consuming, often lagging behind the increasing demand for materials with tailored properties. In this study, we introduce a machine learning-based approach to predict and optimize the mechanical properties of PI materials and their composites. We developed six predictive models to assess PI structures under various conditions, aiming to enhance our understanding of PI mechanical behavior and facilitate the discovery of high-performance PI structures. By analyzing the substructures within top-performing PIs, we identified key structural motifs that contribute to improved tensile strength, modulus, and elongation at break. Furthermore, we examined the influence of fillers on PI composites, revealing that rigid fillers such as SiO2 and graphene oxide (GO) significantly improve mechanical properties, with GO showing versatile enhancement across multiple mechanical properties. We then screened 800,000 virtual PI structures by using our predictive models, identifying several candidates with targeted mechanical properties. These findings provide a basis for the future experimental validation of optimal PI structures and fillers, offering an efficient pathway to accelerate the design of PI materials with targeted mechanical properties. Our study can also be extended to other materials research, serving as a valuable paradigm for the design of polymers and their composites.