A process for the commercial production of diphenolic acid [4-(bis(hydroxyphenyl))pentanoic acid, DPA] in good yield from cellulose-rich sources such as wood, paper, sewage sludge, paper mill sludge and food processing waste via levulinic acid has been developed.

The preparation of the t-butyl ester of DPA enables the formation of homo- and co-polycarbonates in which the blocking group can be removed to give free carboxyl groups along the polymer backbone. Such materials exhibit classic polyelectrolyte behavior. The sodium salt of the homo polycarbonate carboxylate is surprisingly stable to hydrolysis in alkaline solutions. Neutralization of the carboxyl groups with polyvalent counter ions leads to crosslinked gels. The carboxyl groups can also serve as the locus for grafting reactions leading to materials with unusual properties.