Low-surface-energy monomer for ultrathin silicone membrane fabrication: Towards enhanced ethanol/water pervaporation performance

Silicone-based polymers are the most popular materials to prepare pervaporation (PV) membranes for bioethanol recovery from fermentation process. However, the existing silicone composite membranes mostly exhibited limited permeance for ethanol/water separation, which can be attributed to the thick active silicone layers resulting from insufficient spreading of the polymer casting solution on the porous substrate. In the present study, we propose the use of low-surface-energy monomer into casting solution to enhance its spreading ability for ultrathin silicone membrane fabrication. In specific, a poly(dimethyldiethoxylsilane) (PDMDES) casting solution was prepared by limited polymerization of its low-surface-energy monomer dimethyldiethoxylsilane (DMDES), and was then carted on a porous substrate. We show that the surface energy of the partially polymerized casting solution maintained low, and an ultrathin PDMDES active layer with thickness of sub micrometer size was obtained. The physicochemical properties of the PDMDES membrane were further characterized by ATR-FTIR, XRD and TGA, respectively. Upon optimized preparation and operation conditions, the PDMDES composite membrane exhibited a superior flux of 7565.6 g.m(-2).h(-1), while maintained a comparable separation factor when compared to traditional PDMS membranes. Our strategy provides new insights into the development of ultrathin silicone membranes for enhanced bioethanol recovery.