New Aromatic Diacids Containing the Trifluoromethyl Group and their Polyamides

Abstract

A series of new fluorinated, high-temperature polymers has been prepared from 1, 1, - bis(p-carboxyphenyl)-2, 2, 2-trifluoroethanol (3FOH). This diacid was synthesized by oxidation of 1, 1-di(p-tolyl)-2, 2, 2-trifluoroethanol, which was obtained from p-bromotoluene and ethyl trifluoroacetate. The 3FOH was also reacted with dimethyl sulphate to yield 1-methoxy-1, 1- bis(p-carboxyphenyl)-2, 2, 2-trifluoroethane (3FM), and with SOCl2 to produce 1-chloro-1, 1- bis(p-chloroformylphenyl)-2, 2, 2-trifluoroethane (3FCl). These two diacids, as the acid chlorides, were polymerized with six aromatic and four aliphatic diamines to produce polyamides which had viscosities ranging from 0.32 to 1.52 dl g⁻¹, thermal stabilities up to 518 °C in nitrogen and glass transition temperatures from 165 °C to 337 °C. The dielectric constants of these polyamides ranged from 2.64 to 2.99. The 3FM- and 3FCl-containing polyamides were compared with the 6F (hexafluoroisopropylidene) analogues and found to be somewhat less thermally stable and had equal or lower T _gs.