Characterization of end groups in polycarbonates by reactive pyrolysis-gas chromatography

Pyrolysis-gas chromatography using the sample decomposition in the presence of an organic alkali, tetramethylammonium hydroxide (TMAH), was applied for end group determination of industrially available polycarbonate (PC)'s. Various phenolic compounds were observed in the conventional pyrograms of the PC's, which were formed through the C-C bond cleavage as well as that of carbonate linkages. On the other hand, the PC main chain almost quantitatively degraded through reactive pyrolysis at carbonate linkages to yield the dimethyl derivatives of the constituents such as bisphenol-A through a hydrolytic pyrolysis reaction in the presence of TMAH. In a similar manner, characteristic methyl ethers such as anisole and p-tert-butylanisole were formed from end groups. By this method, highly accurate and rapid determination became possible for the contents of their end groups. This information, in turn, enabled accurate estimation of the number average molecular weight of PC's without using any reference polymers.