About Polymers of Intrinsic Microporosity (PIMs)

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An open access (i.e. free) review on PIMs is available from this link.

A polymer demonstrates intrinsic microporosity when its chains are sufficiently rigid and contorted so that they pack inefficiently in the solid state resulting in the formation of interconnected pores. In contrast to other porous materials Polymers of Intrinsic Microporosity (PIMs) do not require a network of covalent bonds to sustain porpim-1_webosity and, hence, are solution processable into robust films and coatings.  PIMs have had a far-reaching influence on academic research in many areas including gas separation membranes, sensors and adsorbents since their invention in 2003 (Patent: WO/2005/012397; Chem. Commun., 2004, 230 and C&EN News of the Week, 2004, 82(3), 13). Rapidly growing global activity is demonstrated by >300 research papers dealing directly with PIMs, mostly published in the last few years, with corresponding authors from over twenty countries. In addition, PIMs have had a strong impact on industrial research with pim-1_graycovering a range of potential applications  as demonstrated by the patent applications from Dow Chemical Company (US), Kimberly-Clark (US), Sepion (US), UOP (US) and Sabic (Saudi Arabia). Most notable are the suite of >20 patents held by the multinational company 3M related to sensors, an application for which they license the original PIM patent (WO/2005/012397). 3M use PIM-1 for the active layer in their elegant colorimetric sensor used as an end-of-service-life-indicator for organic vapour respirator cartridges (http://www.3m.com/ServiceLifeIndicator). Launched onto the global market in 2015, these sensors protect the health of workers exposed to high levels of organic vapours (e.g. car body spray painters). 3M won a British Safety Industry Federation (BSIF) award for this end-of-service-life-indicator at the Safety and Health Expo, London, August 2015.

pim-ea-tb_webIn addition to the dioxin-forming reaction, illustrate by the synthesis of PIM-1, imide and Trögers base (TB) forming reactions can be used to make PIMs.  TB polymerisation (US patent 20130267616) takes advantage of a reaction that was first discovered in 1887 and can be used to make highly rigid PIMs such as PIM-EA-TB that demonstrate excellent selectivity as gas separation membranes (Science, 2013, 339, 303; C&EN News of the Week, 2013, 9(3) 7).