Thermodynamics of 2,6-dimethylphenol, of the reaction of its oxidative dehydropolycondensation, and of the resultant poly(2,6-dimethyl-p-phenylene oxide) at 0-600 K

The temperature dependences of the heat capacities C-p(0) of 2,6-dimethylphenol at 5 - 400 K and poly(2,6-dimethyl-p-phenylene oxide) at 6 - 600 K were studied with vacuum adiabatic and scanning calorimeters. The heat of combustion of the polymer was measured with an isothermal jacketed bomb calorimeter. The results and the corresponding literature data were used to calculate (1) thermochemical parameters (Delta H-f(0), Delta S-f(0), and Delta G(f)(0)) of formation of 2,6-dimethylphenol and poly(2,6-dimethyl-p-phenylene oxide) at T = 298.15 K and p = 101.325 kPa; (2) thermodynamic functions C-p(0), H-0(T) - H-0(O), S-0(T), and G(0)(T) - H-0(O) of the monomer and the polymer at 0 - 600 K, and (3) thermodynamic parameters (at 0 - 600 K and standard pressure) for the reaction of oxidative dehydropolycondensation in bulk 2,6-dimethylphenol with the formation of poly(2,6-dimethyl-p-phenylene oxide). In the entiro temperature range of physical existence of the monomer and the polymer, the reaction of oxidative dehydropolycondensation of 2,6-dimethylphenol thermodynamically is allowed, and the produced poly(2,6-dimethyl-p-phenylene oxide) is thermodynamically stable with respect to depolymerization yielding the starting reactants.