LAUSR

Abstract Four types of diphenylacetylene monomers [Me3SiC6H4C CC6H4R; R = OCH2CH2Br (M1), CH2CH3 (M2), OCH CH2 (M3), and CH CH2 (M4)] were synthesized to facilitate the crosslinking of poly(diphenylacetylene)s via post-polymerization modification. Metathesis polymerizations of M1 and M2 using TaCl5/n-Bu4Sn afforded corresponding high-molecular-weight poly(diphenylacetylene)s (P1 and P2; Mw = 1,370,000 and 1,410,000, respectively). However, the polymerization of M3 and M4 afforded a low-molecular-weight polymer (Mw of 6290) and an insoluble product, respectively. The elimination reaction of the side groups in P1 using t-BuOK yielded poly(diphenylacetylene) with vinyl-ether side groups (P1–V). A crosslinked poly(diphenylacetylene) (C–P1–V) was subsequently synthesized via cationic polymerization of the vinyl-ether side groups of P1–V using BF3·OEt2. Another crosslinked poly(diphenylacetylene) (C–P2–Br) was synthesized via radical coupling of the side chains in P2 using N-Bromosuccinimide/benzoyl peroxide. The crosslinked poly(diphenylacetylene)s exhibited relatively low gas permeability among the poly(diphenylacetylene) derivatives, with oxygen permeability coefficients of 35 and 6.8 barrer for C–P1–V and C–P2–Br, respectively.