Improved performance of PDMS/ceramic composite pervaporation membranes by ZSM-5 homogeneously dispersed in PDMS via a surface graft/coating approach

A homogeneous dispersion of inorganic fillers in polymer matrix is a primary challenge for the advancement of mixed matrix membranes (MMMs) in pervaporation and gas separation. In this work, a surface graft/coating approach was developed for homogeneously dispersing ZSM-5 zeolite in polydimethylsiloxane (PDMS) for preparing ZSM-5 filled PDMS mixed matrix/ceramic composite membranes. Molecular dynamics simulations were carried out to calculate the interaction energy between zeolite and PDMS. It was found that surface modification of zeolite particles could highly improve their interaction with PDMS matrix. The SEM images confirmed the uniform dispersions of surface-modified ZSM-5 particles in PDMS matrix even at highest zeolite loading of 40 wt.%. As revealed in the FT-IR analysis and contact angle measurements, the prepared ZSM-5 filled PDMS membranes exhibited less hydroxyl groups and became more hydrophobic with increasing zeolite loading. The pervaporation experiment in 5 wt.% ethanol-water solution indicated that the homogeneously incorporated ZSM-5 particles improved the selectivity of PDMS membrane, and the separation factor of surface-modified ZSM-5 filled PDMS membrane increased gradually with zeolite loading. This effective dispersion method could be instructive for the fabrication of organic-inorganic composite materials.