Pavel O. Tokarev

Membrane separation is an efficient approach for volatile organic compound (VOC) recovery from industrial off-gases due to its low energy consumption, compact design, and operational simplicity. Membrane-based VOC recovery critically depends on the membrane material, which must exhibit high VOC permeability and selectivity under mixed-gas conditions. In this study, novel highly selective membranes for VOC removal based on polydecylmethylsiloxane (PAMS-10) were synthesized using both polydimethylsiloxane and various α,ω-dienes as cross-linkers: 1,7-octadiene (OD), 1,9-decadiene (DD), and 1,11-dodecadiene (DdD). The influence of cross-linker concentration and length on mechanical, structural, sorption, and transport properties was examined extensively. The combination of three independent experimental methods (time-lag, vapor permeation, and in situ spectroscopic ellipsometry) revealed that increasing α,ω-diene concentration and decreasing its length led to a reduction in the diffusivity and permeability of permanent gases, gaseous hydrocarbons, and VOC vapors. For VOC/N₂ separation, the slightly cross-linked OD-1 membrane and the DdD-5 membrane, cross-linked with long 1,11-dodecadiene, demonstrated outstanding mixed-gas selectivities of 950/921/314/840 and 940/1084/233/1106 for toluene/n-octane/i-octane/n-butyl acetate, respectively. Notably, the DD-5 membrane, cross-linked with 1,9-decadiene, matching the length of the PAMS-10 side chain substituent, exhibited the best mechanical properties and mixed-gas selectivity comparable to the ideal selectivity, a unique behavior attributed to optimal supramolecular organization.

Membrane separation is an efficient approach for volatile organic compounds (VOC) recovery from industrial off-gases due to its low energy consumption, compact design, and operational simplicity. The membrane-based VOC recovery critically depends on the membrane material, which must exhibit high VOC permeability and selectivity. In this study, novel sorption-selective membranes based on polydecylmethylsiloxane (PAMS-10/PDMS) were synthesized using α,ω-dienes of varying lengths as cross-linkers: 1,7-octadiene (OD), 1,9-decadiene (DD), and 1,11-dodecadiene (DdD). The cross-linker lengths were chosen to be shorter than, equal to, or longer than the PAMS-10/PDMS n-decyl side-chain substituent, enabling a systematic investigation of polymer supramolecular structure effects on transport properties.The influence of cross-linker concentration and length on mechanical, structural, sorption, and transport properties was examined in detail. The combination of three independent experimental methods (time-lag, vapor permeation, and in situ spectroscopic ellipsometry) revealed that increasing α,ω-diene concentration and decreasing its length led to a reduction in the diffusivity and permeability of permanent gases, gaseous hydrocarbons and VOC vapors. WAXD-analysis confirmed that n-alkyl side chains formed an interdigitated packing, with the interplanar distance decreasing by up to 0.5 Å which increasing cross-linking density.For VOC/N2 separation, the slightly cross-linked OD-1 membrane and the DdD-5 membrane, cross-linked with long 1,11-dodecadiene, demonstrated mixed-gas selectivities of 950/921/314/840 and 940/1086/233/1106 for toluene/n-octane/i-octane/n-butyl acetate, respectively, significantly exceeding the values reported for conventional PDMS-membranes. Notably, the DD-5 membrane, cross-linked with 1,9-decadiene, matching the length of PAMS-10/PDMS side chain substituent, exhibited mixed-gas selectivity comparable to the ideal selectivity, a unique behavior attributed to optimal supramolecular organization. These findings establish PAMS-10/PDMS membranes as highly efficient materials for VOC recovery applications, highlighting the versatility of cross-linker modification for adjusting transport characteristics.