Poly(methyl methacrylate)/SiO₂ hybrid membranes: Effect of solvents on structural and thermal properties

In this paper, hybrid organic-inorganic membranes were prepared using three different solvents and characterized. The hybrid membranes were fabricated using sol-gel technique, which had polymethyl-methacrylate (PMMA) and tetraethyl orthosilicate (TEOS) as materials, with 80/20 ratio. The thin films were then characterized using FTIR, SEM, EDX, and mapping techniques. From the preliminary characterization, hybrid membranes were found to have nano and ultra scale tight-pores ranges, which was influenced by the solvent used. The SEM images clearly show that hybrid membranes have homogenous and smooth surface. FTIR spectroscopy uncovered all the signature peaks characteristic of silicate structures in the near-surface regions. Fingerprints of Si-O-Si groups in cyclic and linear molecular substructures were also present. From DSC analysis, the T_g value of the PMMA moieties in hybrids membranes was in the order H-15-Toluene < Pure PMMA < H-15-THF < H-15-DMF. Furthermore, from TGA analysis it was found that the hybrid membranes have higher thermal stability compared with that of pure PMMA. EDX and mapping analysis showed that the composition and distribution of particles in the membranes were different and dependent on the solvents used.