Calorimetric study of activated polycondensation of tris(pentafluorophenyl)germane

The activated polycondensation of tris(pentafluorophenyl)germane in the presence of triethylamine used as an activating agent was studied by the reaction calorimetry technique. The existence of two heat-release maxima was detected, thereby suggesting the nonsimultaneous occurrence of the activation reaction, involving the formation of ion pairs from the monomer and the activator, and of the subsequent reaction of chain growth. Relationships between the enthalpy of polycondensation and the activator-to-monomer ratio were determined. Analysis of these relationships led the authors to infer that two mechanisms of polycondensation are operative. When the activating agent is in excess, the convergent mechanism holds true, according to which a hyper-branched perfluorinated poly(phenylenegermane) with M n = 5 x 10 4 forms; ΔH 0 polycon = -180 kJ/mol of the monomer. The yield of the target polymer was as high as 93-95%. The maximum polycondensation rate was achieved 20 min after mixing of the reagents.