The fabrication of ultrathin films and their gas separation performance from polymers of intrinsic microporosity with two-dimensional (2D) and three-dimensional (3D) chain conformations

The expansion of the use of polymeric membranes in gas separation requires the development of membranes based on new polymers with improved properties and their assessment under real operating conditions. In particular, the fabrication of ultrathin films of high performance polymers that can be used as the selective layer in composite membranes will allow large reductions in the amount of the expensive polymer used and, hence, the cost of membrane fabrication. In this contribution, two polymers of intrinsic microporosity (PIMs) with very different chain configurations (two-dimensional, 2D, chains or conventional contorted three-dimensional, 3D, conformation) have been compared in their ability to form ultrathin films, showing the relevance of polymer design to obtain compact and defect-free films. Monolayers of the 2D polymer PIM-TMN-Trip can be efficiently deposited onto poly[1-(trimethylsilyl)-1-propyne] (PTMSP) to obtain composite membranes with a CO2/N2 selectivity similar to that of the corresponding thick membranes of the same PIM using only a small fraction of the selective polymer (less than 0.1%).The research leading to these results has received funding from the European Community Seventh Framework Program (EU PF7) (FP7/2007-2013), under grant agreement number 608490, project M4CO2. Financial support from the Spanish MINECO (Ministry of Economy and Business) and FEDER (European Regional Development Fund) (MAT2016-77290-R), the Aragón Government (E31_17R and T43_17R) and the ESF is gratefully acknowledged. J. S.-L. thanks the Spanish Education Ministry Program FPU2014 for his PhD grantPeer reviewe