High-Performance Silicone Membranes for VOC/N2 Separation: A New Crosslinking Strategy via Octyl-Grafted Poly(hydromethylsiloxane)

Membranes made of polyoctylmethylsiloxane (POMS) have emerged as an attractive alternative for volatile organic compound (VOC) separation and recovery. We developed an octyl-modified silicone rubber (OMSR) membrane for VOC/N2 separation by a novel strategy. The OMSR membrane was made via the side-chain cross-linking of the poly(vinylmethylsiloxane) and a tailored octyl-grafted poly(hydromethylsiloxane). The octyl side chains were enriched around the cross-linking points composed of the supramolecular structure with octyl-rich parallel polysiloxane domain, which determined the selective transport of VOCs relative to N2. Compared to membranes without octyl, the OMSR membranes exhibited excellent thermal and mechanical stability and simultaneously high permeability and selectivity in VOC/N2 separation, e.g., with >70,000 Barrer of permeability (5.7 times higher) and >240 (3.5 times higher) of selectivity with toluene/N2. We demonstrated that this unique structure has the potential to overcome the permeability–selectivity trade-off relationship, producing a promising class of membranes for removal of VOCs.