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POLYMERS OF INTRINSIC MICROPOROSITY Polymers of intrinsic microporosity (PIMs) are glassy polymers that possess high free volume because their rigid, contorted macromolecular backbones cannot easily pack together to fill space.	A PIM cannot undergo large-scale changes in conformation because it does not have any single bonds in the backbone about which rotation can easily occur (the backbone typically has a fused-ring or ladder-like structure). However, the backbone twists and turns because it incorporates sites of contortion (e.g., spiro-centres).
MICROPOROSITY According to an IUPAC definition, a micropore has dimensions <2 nm. Within a micropore, small molecules exhibit enhanced adsorption, due to multiple interactions with pore walls.	INTRINSIC MICROPOROSITY Intrinsic microporosity refers to a continuous network of interconnected intermolecular voids, which forms as a direct consequence of the shape and rigidity of the component macromolecules.
PIM-1 The prototypical PIM is referred to as PIM-1. PIM-1 is synthesized by a step-growth polymerization involving nucleophilic aromatic substitution reactions.	P.M. Budd et al., Chem. Comm., 2004, 230. P.M. Budd et al., Adv. Mater., 2004, 16, 456.
	PIM-1 is a yellow, fluorescent polymer that exhibits high internal surface area in the solid state. Brunauer-Emmet-Teller (BET) analysis of gas adsorption data typically gives an apparent surface area in the range 600-800 m^2 g^-1.
PIM-1 is soluble in solvents such as chloroform and tetrahydrofuran, and can be processed from solution into powders, coatings, films and fibres.