POLYCARBONATE SYNTHESIS BY THE MELT PHASE CARBONATE-ESTER INTERCHANGEREACTION OF BISPHENOL-A DIACETATE WITH DIMETHYL CARBONATE

The molecular weight of polycarbonate formed by the carbonate-ester in terchange reaction of bisphenol-A diacetate (BPAC(2)) and dimethyl car bonate (DMC) was found to depend on the composition of the oligomer fo rmed in its first stage. At a [DMC] : [BPAC(2)] ratio of 2, an oligome r with relatively higher acetate end group concentration was formed. T his upon further polycondensation yielded a polycarbonate of inherent viscosity, 0.2-0.25 dL/g. Upon addition of DMC at a later stage in the oligomer-forming reaction, an oligomer containing relatively higher c arbonate end groups could be obtained. These oligomers gave polycarbon ates higher inherent viscosity, 0.4-0.5 dL/g. It is therefore proposed that oligomers having carbonate end groups are more reactive in self- polycondensation than those containing acetate end groups. (C) 1995 Jo hn Wiley & Sons, Inc.