High Surface Area Nanoporous-Crystalline Polymer Films

Based on a commercially available thermoplastic polymer (poly(2,6-dimethyl-1,4-phenylene) oxide, PPO), nano-porous-crystalline (NC) polymerfilms with a surface area (SA)higher than 600 m2g-1and with exceptionally fast organicpollutant uptakes are presented. Preparation procedures requirefast crystallizations of amorphousfilms, as induced by high uptakesof nonvolatile guest molecules (typically in the range 70-90 wt%), followed by guest exchange with a volatile guest. The high SAof these NC PPOfilmsisassociatedwithananofibrillarmorphology, analogous to those observed in physically cross-linked PPO aerogels. Organic pollutant diffusivities for high-SA NC PPOfilms are much higher than for other high-diffusivity PPOfilms, like for example those exhibiting NC phases with chain axes (and hence crystalline channels) being preferentially perpendicularto thefilm plane. Much higher diffusivities are observed both for guest sorption from vapor phase and from diluted PPO aqueoussolutions and for guest desorption. Surprisingly, kinetics of guest uptakes from high-SA NC PPOfilms are even faster than for NCPPO aerogels and then much faster when referred to volume of the sorbent material. Because of their extremely fast kinetics ofpollutant uptakes, associated with high thermal and mechanical stability, these new high-SA NC PPOfilms are expected tofind manyapplications, mainly in pollutant remediation and molecular sensors