Regulating Pore Hierarchy and Thermal Stability of Polymethylsilsesquioxane Aerogels through Multiscale Graphite Derivatives

Polymethylsilsesquioxane (PMSQ) aerogels are promising thermal-insulation materials due to their low density and thermal conductivity. However, simultaneously regulating their pore structure and thermal stability while preserving thermal insulation remains challenging. In this work, PMSQ aerogels doped with multiscale graphite derivatives (GD/PMSQ) were prepared under ambient pressure drying, and the roles of graphite derivatives in pore structure evolution and thermal stability were investigated in detail. It was found that the incorporation of graphite derivatives preserves the three-dimensional porous structure of PMSQ aerogels, while promoting a transition from a quasi-single-scale macroporous network to a hierarchical pore architecture. The extent of the pore structure evolution is closely related to the dimensionality and size of the graphite derivatives. Notably, all GD/PMSQ aerogels exhibit low thermal conductivity (29–32 mW/m/K), comparable to that of the pristine PMSQ aerogels. Fourier transform infrared spectroscopy analysis confirms that the primary chemical structure of the PMSQ matrix remains intact after the incorporation of graphite derivatives. Thermal analysis further demonstrates that graphene, reduced graphene oxide, and carbon nanotubes lead to an overall enhancement in the thermal stability of PMSQ aerogels, with carbon nanotube-containing samples exhibiting the most pronounced effect, as reflected by an increase in the onset decomposition temperature from 438.37 to 564.59 °C. These results demonstrate that the pore hierarchy and thermal stability of PMSQ aerogels can be effectively regulated by using graphite derivatives without compromising their inherent lightweight and thermal insulation properties, providing a useful reference for the rational structure–property design of PMSQ aerogels.