Thermoplastic molecular sieves

An inexpensive and reusable thermoplastic material that is promising in the field of chemical separations, and in particular of water and air purifica tion from volatile organic compounds, is presented. This semicrystalline ma terial based on syndiotactic polystyrene comprises a nanoporous crystalline phase where guest molecules can be clathrated. Changes of conformational e quilibria of some chlorinated hydrocarbons upon clathration have been ratio nalized by a molecular mechanics approach. This sheds light on the nature o f the host-guest interactions: although the van der Waals interactions are most relevant, the observed conformations for chlorinated guest molecules a re essentially associated with electrostatic attractive interactions of qua drupolar conformers with a substantially quadrupolar electrostatic field of the crystalline cavity.