The synthesis of bisphenol A poly(carbonate–ester) copolymers was studied by phase‐transfer catalysis and modified interfacial polymerization. Only low molecular weight copolymers were prepared directly from dicarboxylic acids, phosgene, and bisphenol A by an interfacial process that involves the use of pyridine as catalyst, HCl acceptor, and weak base. To avoid the use of tertiary amines, which can be difficult to remove from the polymer products, and to produce higher molecular weight copolymers from the same dicarboxylic acid precursors another synthetic method was developed. This more effective method required careful pH control that was achieved by the selective use of the weak‐base potassium carbonate in the first stage of the process. Moreover, elevated reaction temperatures (∼65–70°C) and phase‐transfer catalysis were used. The carbonate–ester copolymers prepared by this technique had consistently high intrinisic viscosities, little or no anyhydride microstructure, and higher degrees of ester unit incorporation than those produced by the pyridine‐catalyzed method. These copolymers also had glass transition temperatures (Tg) 20–30°C higher than bisphenol A polycarbonate homopolymer. An analytical method for determining quantitatively the amount of ester units in the bisphenol A poly(carbonate‐esters) was developed by using Fourier transform infrared spectroscopy (FT‐IR). Agreement between this FT‐IR method and a quantitative nuclear magnetic resonance (NMR) method was found to be reasonable, especially for copolymers with ester unit percentages lower than 40%.

An exhaustive end‐capping method for the analysis of silicone copolymers and networks using hexamethyldisiloxane in the presence of trifluoromethanesulfonic acid was demonstrated. The hard block of a polymide‐co‐polysiloxane was isolated by the equilibration of the copolymer with a large excess of hexamethyldisiloxane and subsequently examined by size exclusion chromatography. Addition cured polyimidesiloxane networks were also equilibrated with an excess of the disiloxane and the resulting oligmoers characterized by gas chromatography of the end‐capped fragments.

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