Cycle Formation in the Polycondensation of Potassium 3-Bromomethyl-5-methylbenzoate

Abstract

Potassium 3-bromomethyl-5-methylbenzoate 2K, preformed or obtained from 3-bromomethyl-5-methylbenzoic acid 2 by exchange reaction with potassium undecanoate 5K, was polymerized in bulk or in 1-methyl-2-pyrrolidone (NMP), in the presence or not of a trifunctional core molecule. GPC analyses of the reaction products have shown that small cyclic oligomers (usually from C2 to C6) are formed in all the cases. MALDI-TOF MS of polymers have shown that, in the range of masses examined, those prepared by polymerization of 2K in bulk or in NMP are almost exclusively formed of cycles. In the polymer obtained by polymerization, in NMP, of 2 in the presence of 5K linear and cyclic species coexist. In the polymer resulting from the polymerization of 2K in the presence of 2,4,6-tris(bromomethyl)mesitylene (TBMM) the expected three-arm stars are predominant and the content in cycles is relatively low and obviously the lowest of all the other prepared polymers. The formation of cycles (large and/or small) is an inherent component of the polycondensation of 2K. Cyclization strongly contributes to the limitation of molar masses of the reaction products. MALDI-TOF mass spectrum (reflector mode) of PB2 (run 3, Table 1). Symbols: •, Cn; ×, (Cp[D])LqOCH3 and +, (Cp[D])LqBr.