This seminar is part of the Distinguished Chemical Engineering Seminar Series aimed at exploring the views from distinguished academics from around the world in shaping the future of Chemical Engineering, the profession and its research agenda. See the full programme of seminars. Join the conversation on social media using #impChemEng.
Abstract
Intrinsic microporosity is defined as a continuous network of interconnected intermolecular microcavities, which is formed as a consequence of the contorted shape and chain rigidity of the polymer structure. The restricted chain rotation originating from sites of contortion or spiro centers leads to an inefficiently packed matrix with high free volume elements, typically above 20% FFV. ‘Polymers of Intrinsic Microporosity’ (PIMs) are high-free-volume microporous solvent-soluble polymers having rigid ladder-like structures incorporating contorted centers. With high surface areas, PIMs are considered as promising materials for membrane-based separations because of high product throughput or flux. In particular, they have been explored for non-aqueous nanofiltration (Imperial College) and more widely for gas separation, because of their very high gas permeability. In 2004, Budd and McKeown reported ‘PIM-1’ and other related structures, as a new class of high molecular weight microporous ladder polymer. PIM-1 is the most studied material of this polymer class for several reasons: (a) it can be readily prepared from commercial monomers, (b) it has relatively high molecular weight and low polydispersity, and (c) good mechanical properties compared with many other PIMs. PIMs exhibit very high gas permeabilities, though lower than poly(trimethylsilyl propyne) (PTMSP). While the latter is prone to rapid and significant reductions in permeability, resulting from a collapse in free volume, PIMs have no (or less) rotational freedom, making them less inclined to free volume collapse. Since the first published reports of PIM-1, the area of PIMs for gas separation has grown rapidly. Highlights of some of the speaker’s and several other researchers’ work on PIMs will be given, particularly on more recent work on a related class of microporous polyimides incorporating Tröger’s Base (TB), which is a rigid non-planar bridged bicyclic amine.
Michael D. Guiver
State Key Laboratory of Engines (SKLE), School of Mechanical Engineering
Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
Tianjin University, Tianjin 300072, China