Transition‐Metal‐Catalyzed Chain‐Growth Polymerization of 1,4‐Diethynylbenzene into Microporous Crosslinked Poly(phenylacetylene)s: the Effect of Reaction Conditions

Abstract

Chain‐growth polymerization of 1,4‐diethynylbenzene into conjugated crosslinked polyacetylene‐type poly(1,4‐diethynylbenzene)s (PDEBs) is reported. While metathesis catalysts (WCl6/Ph4Sn, MoCl5/Ph4Sn, Mo Schrock carbene) fail in this polymerization, insertion Rh catalysts ([Rh(nbd)acac], [Rh(nbd)Cl]2) provide microporous PDEBs in high yields. The Brunauer–Emmett–Teller (BET) surface, SBET, of PDEBs prepared with [Rh(nbd)acac] increases, in dependence on the polymerization solvent, in the order: THF << pentane < benzene < methanol < CH2Cl2. SBET further increases with both increasing monomer concentration and increasing polymerization temperature and reaction time, reaching a highest value of 1469 m2 g−1. In addition to micropores, PDEBs contain mesopores. The mesopore volume and average mesopore diameter increase with the time and the temperature of the polymerization up to 2.52 cm3 g−1 and 22 nm (72 h, 75 °C). The post‐polymerization thermal treatment of PDEB (280 °C) results in formation of new crosslinks and modification of PDEB texture and sorption behavior manifested mainly by enhancement of H2 adsorption capacity up to 4.55 mmol g−1 (77 K, 750 Torr). image