Preparation of Poly(thioarylene)s from Cyclic Disulfide Oligomers

A series of poly(thioarylene)s, including fluorinated poly(thioarylene)s, was prepared from cyclic disulfide oligomers and diiodo or dibromo aromatic compounds in diphenyl ether solution at 270 °C. The cyclic disulfide oligomers were derived from 4,4'-thiobis(benzenethiol) and 4,4'-biphenyldithiol, respectively. Diiodo monomers had to be used in excess (∼4%) to obtain the highest molecular weight polymers, while equivalent amounts of dibromo monomers could be used. 1,4-Diiodobenzene gave poly(thio-1,4-phenylene) (PPS) with a Tg of 88 °C and a Tm of 286 °C, and 1,4-dibromobenzene gave PPS with a Tg of 92 °C and a Tm of 275 °C by reacting with the cyclic disulfide oligomers derived from 4,4'-thiobis(benzene thiol). Poly(thiobiphenylene) obtained from cyclic disulfide oligomers derived from 4,4'-biphenyldithiol had a melting point of 454 °C. Fluorinated diiodo or dibromo monomers have much lower reactivities toward the thiyl radical substitution reaction, and only low molecular weight polymers were obtained. All of the poly(thioarylene)s prepared have very high thermal stabilities as indicated by TGA.