Synthesis and radical polymerization of 2-(p-vinylbenzyl) dibenzothiophene

A novel monomer having a dibenzothiophene moiety, i.e. 2-(p-vinylbenzyl)dib enzothiophene (1) was prepared by the Ni-catalyzed coupling reaction of 2-b romodibenzothiophene with the Grignard reagent of p-chloromethylstyrene. Th e radical homopolymerization of 1 and its copolymerization with styrene (St ) were carried out at 60 degrees C for 20 h in chlorobenzene (3 M) using AI BN (5 mol%) as an initiator to obtain the corresponding polymers in high yi elds. From TGA and DSC analyses, both 10% weight-loss and glass transition temperatures of the copolymers were found to become higher as the content o f 1 increased. A polymer having dibenzothiophenium salt moieties [poly(sulf onium salt), 3] was prepared by the reaction of 2 with CH3I-AgBF4 in CH2ClC H2Cl at r.t. for 24 h. The polymer (3) was found to contain 63 mol% of the methyldibenzothiophenium tetrafluoroborate unit. The thermal decompositions of 3 was observed in two steps, where the decomposition at lower temperatu re was speculated to take place via the elimination of methyl tetrafluorobo rate moieties. (C) 1999 Elsevier Science B.V. All rights reserved.