Effect of Polyvinyl Alcohol Modified Silica Particles on the Physical and Gas Separation Properties of the Polyurethane Mixed Matrix Membranes

Silicon based particles were prepared using tetraethoxysilane (TEOS) as a silica monomer, and low concentration of polyethylene oxide-polypropylene oxide block copolymer (pluronic) with polyvinyl alcohol (PVA) as templating agents. The synthesized particles showed higher polarity compare with conventional silica particles. PU/silica mixed matrix membranes (MMMs) were prepared by solution casting technique. The membranes were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and differential scanning calorimetry (DSC). FT-IR result confirmed the existence of PVA in the final structure of the synthesized silica network. The SEM micrographs indicated an appropriate distribution of silica particles in the polymer matrix. Gas transport properties of membranes were studied for pure CO₂, CH₄, O₂ and N₂ gases at 10 bar and 25 ^∘C. The results showed that the permeabilities of CH₄ and CO₂ enhanced whereas that of other gases decreased with increasing the modified silica contents. In the membrane with 10 wt.% silica content, an enhancement of CO₂/CH₄ (α ≈ 7.7) and CO₂/N₂ (α ≈ 91.4) selectivities was observed.