The potential of polymers of intrinsic microporosity (PIMs) and PIM/graphene composites for pervaporation membranes

Abstract

Pervaporation (PV), a membrane process in which the feed is a liquid mixture and the permeate is removed as a vapour, offers an energy-efficient alternative to conventional separation processes such as distillation, and can be applied to mixtures that are difficult to separate, such as azeotropes. Here the principles of pervaporation and its industrial applications are outlined. Two classes of material that show promise for use in PV membranes are described: Polymers of intrinsic microporosity (PIMs) and 2D materials such as graphene. The literature regarding PV utilizing the prototypical PIM (PIM-1) and it hydrophilic hydrolysed form (cPIM-1) is reviewed. Self-standing PIM-1 membranes give competitive results compared to other membranes reported in the literature for the separation of alcohols and other volatile organic compounds from aqueous solution, and for organic/organic separations such as methanol/ethylene glycol and dimethyl carbonate/methanol mixtures. Blends of cPIM-1 with conventional polymers improve the flux for dehydration of alcohols. The incorporation of fillers, such as functionalised graphene-like fillers, into PIM-1 to form mixed matrix membranes can enhance the separation performance. Thin film composite (TFC) membranes enable very high fluxes to be achieved when a suitable support with high surface porosity is utilised. When functionalised graphene-like fillers are introduced into the selective layer of a TFC membrane, the lateral size of the flakes needs to be carefully controlled. There is a wide range of PIMs and 2D materials yet to be explored for PV applications, which offer potential to create bespoke membranes for a wide variety of organic/aqueous and organic/organic separations.

Semi-Interpenetrating Polymer Network Electrolytes Based on a Spiro-Twisted Benzoxazine for All-Solid-State Lithium-Ion Batteries

“…According to Polu et al , , an increasing fractional free volume in the entire polymer matrix would certainly enhance Li + transportation. To serve this purpose, the incorporation of twisted units such as spirobisindane, spirobifluorene, triptycene, or Tröger’s base onto the polymer backbones was commonly used to directly create the elements of intrinsic microporosity and high free volume with an appropriate size distribution. − This strategy was also reported in a high-performance membrane for separation technology, namely, polymer of intrinsic microporosity (PIM) membranes. − …”

Continuous Flow Upgrading of Selected C2–C6Platform Chemicals Derived from Biomass

“…The development of efficient, reliable and scalable tools for both upstream (biomass to platforms) and downstream (platforms to added value molecules) in-line purifications amenable for the specifications of bio-based chemicals can be foreseen as an important research field for the next decade (Perspective 4 , In-line purification, Figure ). Other technologies such as in-line distillation , and pervaporation − present great potential of development. However, they have not been applied yet to the separation in continuous flow of bio-based components.…”

Mixed matrix membranes derived from a spirobifluorene polymer of intrinsic microporosity and polyphenylene networks for the separation of toluene from dimethyl sulfoxide

“…4 In the pervaporation process, the feed is a liquid mixture and a vacuum is applied to remove permeate as a vapour. 5 Recently, we have been exploring the use of PIM-based membranes for the recovery of aromatic hydrocarbons from polar solvents. 6 Benzene, toluene and xylenes, which are important feedstocks for the chemical industry, are commonly removed from other products in a catalytic reformate by an extractive distillation with a polar solvent.…”