Surface polarity of porous polymers at different coverages

摘要

At different surface coverages (theta s), the dispersion component (Delta F-disp) and specific components (induction and orientation interactions; Delta F-io and donor-acceptor interactions; Delta F-da) of the sorption free energy and the polarities were calculated for three porous polymers: the microporous styrene-divinylbenzene copolymer Dowex L-285, the microporous hypercrosslinked polystyrene MN-200, and the macroporous styrene-divinylbenzene copolymer Polysorb-1. Two methods were used to calculate DFdisp, DFio and Delta F-da: the linear free energy relationship method and the Dong polarization method. For styrene-divinylbenzene sorbents, DFdisp decreased with u, whereas Delta F-io and Delta F-da increased; this caused the polarity to rise. This phenomenon was caused by the sorbat-sorbat lateral interactions on the polymer's surface; these were stronger for polar molecules. In the case of hypercrosslinked polystyrene, Delta F-disp and Delta F-io varied equally, and the polarity was almost constant. This trend could be explained by the absorption of the molecules into the bulk of the polymer; this prevented lateral interactions. We concluded that the lateral interactions were a function of the porous polymer's surface properties. (C) 2016 Wiley Periodicals, Inc.