Synthesis and Properties of Fluorine-Containing Poly(arylenemethylene)s as New Heat Resistant Denatured Phenolic Resins

Abstract

We report the synthesis of fluorine-containing poly(arylenemethylene)s as a new heat-resistant denatured phenolic resin by addition-condensation or Friedel-Crafts polymerization. In the case of polymerization of 2,2-bis(4-methoxyphenyl)hexafluoropropane (1a) with an equimolar amount of formaldehyde, the polymerization proceeded homogeneously to give the polymer 2a (Mn 8,200, Mw/Mn 2.1) in 71% yield. The FT-IR, 1H NMR and 13C NMR spectra of 2a revealed that it had arylene-methylene units on the polymer backbone. The polymerizations of 3-(trifluoromethoxy)benzyl bromide (1b) or 4-(trifluoromethoxy)benzyl bromide (1c) via the Friedel-Crafts polymerization using aluminum chloride as a catalyst produced the polymer 2b and 2c in 38% and 16% yield, respectively. From the TGA, the temperatures at 10% loss in weight (T10) of 2a and 2c were found to be 425 and 298 °C, respectively. As compared to the non-fluorinated poly(arylenemethylene) derived from 2,2-bis(4-methoxyphenyl)propane-formaldehyde polymer (2d) (T10=397 °C), 2a showed high thermostability in terms of the temperature of T10. The results indicated that the thermal stability of poly(arylenemethylene)s was enhanced by the introduction of fluorine moieties in the polymer.