Preparation of Porous Epoxy Resin Materials by Reaction-Induced Phase Separation Regulated Using Fumed Silica

Significant attention has been paid to improving the microstructure of polymer blends by stabilizing their phase interface with inorganic nanoparticles. During the preparation of porous epoxy resin materials by reaction-induced phase separation, the microstructure of the porous epoxy resin materials is controlled by fumed silica. The phase separation and chemical kinetics have been monitored by optical microscopy, differential scanning calorimetry, and rheometry, and the microstructure has been characterized by scanning electron microscopy and mercury porosimetry. Upon comparison of the phase separation process of the epoxy blend before and after the addition of fumed silica, it is evident that the fumed silica are preferentially dispersed in the pore-forming agent phase; at the phase interface, the coarsening rate of the phase structure is decreased, the reaction rate is decreased, and the gelation is delayed. With an increase in the mass fraction of the fumed silica, the pore size of the porous epoxy resin materials decreases gradually, and the structure is fined. This result provides an approach for the fine control of the microstructure of porous epoxy resin materials. In addition, the fumed silica in the porous epoxy resin material can be removed by acid etching without affecting the structure of the porous material. Furthermore, the effect of the fumed silica on the structure of the closed-hole epoxy resin system has been investigated.