Preparation of silica–poly(methyl methacrylate) composite with a nanoscale dual-network structure and hardness comparable to human enamel

Abstract Objective This study aims to prepare an organic–inorganic composite with a nanoscale dual-network structure composed of a ceramic skeleton and infiltrated resin to mimic the mechanical properties of human enamel. Methods A porous silica block was obtained by sintering a green body composed of SiO 2 nanoparticles and poly(vinyl alcohol) organic binder. Methyl methacrylate monomers were infiltrated into the porous silica block and thermally polymerized to form poly(methyl methacrylate) (PMMA). A monolithic SiO 2 –PMMA composite was obtained, and its nanoscale structure was investigated. Its mechanical properties were characterized by Vickers hardness, elastic modulus, and flexural strength tests. Results The SiO 2 –PMMA composite had a nanoscale dual-network structure composed of a silica–ceramic skeleton with PMMA-filled continuous 10–20 nm sized pores. The mechanical properties of the composite depended on the SiO 2 content, which could be adjusted by modifying sintering time of the porous silica block. The mechanical properties of the composite exhibited wide variations with Vickers hardness values of 54–756, elastic moduli of 7–54 GPa, and flexural strengths of 75–120 MPa. Significance The preparation of a SiO 2 –PMMA composite with a dual-network structure at the nanoscale was demonstrated, and the composite was characterized with respect to its hardness compatibility with human enamel.