Rapid Generation and Control of Microporosity, Bimodal Pore Size Distribution, and Surface Area in Davankov-Type Hyper-Cross-Linked Resins

Abstract

Synthesis of Davankov-type hyper-cross-linked resin beads has been carried out using gel-type and permanently porous poly(divinylbenzene-co-vinylbenzyl chloride) (DVB−VBC) precursor resins without any external electrophile. Of the Lewis acids examined (FeCl3, AlCl3, SnCl4), FeCl3 was by far the most effective catalyst. Rather remarkably in the case of a gel-type 2 mol % DVB−VBC precursor, extensive microporosity was generated within only 15 min of initiating the cross-linking reaction, yielding a surface area (N2 sorption/BET) of ∼1200 m2 g-1, which rose steadily to a maximum approaching 2000 m2 g-1 after 18 h. In the case of porous DVB−VBC precursor resins, the presence of discrete pores in the precursor, accompanied by a micropore fraction on hyper-cross-linking, yields resins with a clearly bimodal distribution of pores. Manipulation of the Friedel−Crafts reaction variables and the structure of the precursor resin allows final resin products to be prepared with surface areas in the range ∼300−2000 m2 g-1.