Fabrication of Poly(MMA-co-ST) Hybrid Membranes Containing AgCl Nanoparticles by in Situ Ionic Liquid Microemulsion Polymerization and Enhancement of Their Separation Performance

To obtain high-performance membranes for the separation of aromatic/aliphatic hydrocarbons, AgCl nanoparticles were synthesized in a water-in-oil microemulsion using the ionic liquid 1-dodecyl-3-methyl imidazoium chloride (C₁₂mimCl) as surfactant and methyl methacrylate-styrene (MMA-St) mixture as oil phase. Then, AgCl/poly­(MMA-co-St) hybrid membranes were prepared by microemulsion by in situ polymerization. UV–visible spectrophotometry and transmission electron microscopy (TEM) were used to explore the influence of the St-to-MMA ratio in the oil phase on the morphology of AgCl nanoparticles in the microemulsion. The change in morphology of AgCl in membranes after polymerization was characterized by scanning electron microscopy and TEM. The separation performance of different hybrid membranes was evaluated by swelling–sorption experiments and pervaporation experiments. Results showed that adding a low amount of St slightly influenced the size and distribution of AgCl particles. Given the improvement in benzene separation, the performance of hybrid membranes after adding St was higher than that of AgCl/PMMA membranes. The maximum separation factor of hybrid membranes using MMA and St as the oil phase reached about 27 and exceeded twice that of AgCl/PMMA membranes. When the ratio of MMA and St was less than 2, the strong π combination between St and AgCl caused a large aggregation of AgCl particles both in the microemulsion and in the membranes, which evidently reduced the separation performance of the membranes. Increased AgNO₃ concentration led to the formation of more AgCl particles in the microemulsion, which enhanced the separation performance of hybrid membranes. At high AgNO₃ concentration, more particles with short distances more easily aggregated, thereby obviously reducing the separation performance of the membranes.