Thermal treatment of poly[ethylene-alt-2,2-bis(1,4-phenylene)propane carbonate]: A reinvestigation

The final product of the thermal treatment of poly[ethylene-alt-2,2-bis(1,4-phenylene)-propane carbonate] (polymer 1 ) at 280°C under vacuum was characterized as a random copolymer containing both ether and carbonate groups and not as pure bisphenol A polycarbonate as reported previously by other authors. Infrared and NMR spectroscopy were used to detect the changes of the polymer structure during the thermal treatment; the resulting polymers were also characterized by measuring their intrinsic viscosity. During the thermal treatment different reactions occur: exchange reactions (which would lead to a random copolycarbonate), and intramolecular elimination of ethylene carbonate and carbon dioxide. This last elimination is responsible for the formation of ether groups which, being stable under the reactions conditions, prevent the complete elimination of the aliphatic moieties. The final random copolymer was also prepared by reacting pure bisphenol A polycarbonate (PC) and ethylene carbonate; this confirms the occurrence of exchange reactions, which lead to a random copolycarbonate having a structure similar to the polymer deriving from polymer 1 . Surprisingly, in the presence of a typical exchange reaction catalyst such as dibutyltin dimethoxide or titanium tetrabutoxide, the final product of the thermal treatment of polymer 1 is pure PC.