Novel hybrid membranes by incorporating SiO2 nanoparticles using in situ microemulsion polymerization: preparation, characterization and enhancement in the performance for CO2/N2

SiO2 nanoparticles were synthesized in a water-in-oil microemulsion using a triblock copolymer as the surfactant and methyl methacrylate as the oil phase. Then, SiO2/poly(methyl methacrylate) (PMMA) hybrid membranes were prepared by in situ microemulsion polymerization. The separation of CO2/N-2 gas mixtures was studied using these novel membranes. Both the gas permeability and separation performance of the hybrid membranes first increased and then decreased with SiO2 content. When the SiO2 content was 4.0 wt%, the CO2 permeability and permeability selectivity of the membranes for CO2/N-2 gas mixtures were both at a maximum. For comparison, two commercially available SiO2 nanoparticle materials were also used to synthesize SiO2/PMMA membranes by solution polymerization. The particle size of SiO2 in the microemulsion was close to the two commercially available SiO2 nanoparticle materials. The SiO2 nanoparticles formed in the microemulsion were distributed more homogeneously in the membranes than the commercially available nanoparticles because of the protection by the water droplets. Moreover, the SiO2 nanoparticles formed in the water droplets and reverse microemulsion had a strong polar surface. Therefore, the SiO2/PMMA hybrid membrane formed by the in situ microemulsion polymerization had better performance than the hybrid membranes made with commercially available SiO2 nanoparticles.