Interpenetrating polymer network-based composites reinforced by polysilsesquioxanes: Molecular dynamic simulations and experimental analysis

The paper presents a new material (named PMPP) with interpenetrating polymer network (IPN) formed by rigid polysilsesquioxane and flexible poly(hexamethylene diisocyanate)/poly(ethylene glycol) (PHMDI/PEG). Based on the network, polysilsesquioxanes with different structures, such as ladder-like polysilsesquioxane (PPSQ), cage-like polysilsesquioxane (T7POSS) and reactive ladder-like polysilsesquioxane (VPOSS), were selected to further modify PMPP. All samples were subjected to mechanical analysis, thermal analysis and combustion analysis and simulated by molecular dynamics (MD) and MesoDyn simulation. The introduction of polysilsesquioxanes obviously improved the flexural strength, tensile strength, heat resistance and fire resistance due to the strong interaction between polysilsesquioxanes and PMPP network structures. The results of solubility parameters (δ), radial distribution functions (RDF), Flory-Huggins parameters (χ) and mesoscopic morphologies showed that T7POSS and VPOSS had stronger interaction, better compatibility and dispersion in PMPP, thereby providing theoretical foundation for performance improvements.