Diphenolic acid ester polycarbonates

Polycarbonates of methyl, ethyl, n‐propyl, n‐butyl, and n‐hexyl 4,4‐bis(4‐hydroxyphenyl)pentanoate and copolycarbonates with bisphenol‐A of 0.5‐0.9 intrinsic viscosity in dioxane were prepared by a homogeneous CH2Cl2pyridine method and the physical properties determined. Increasing the number of carbon atoms in the DPA ester alcohol group from 1 to 6 decreased the initial softening temperature of the polycarbonates from 126 to 58°C. ; this change also increased the solubility of the polycarbonates in aromatic solvents and in three ketone solvents. O2 transmission rates were not affected by increasing the ester chain length. CO2 transmission rates increased as DPA ester alcohol chain length increased. Methyl DPA polycarbonate had the highest tensile strength and per cent elongation and the lowest O2 and CO2 transmission rates.