Depolymerization of Poly(indene carbonate). A Unique Degradation Pathway

The depolymerization of poly(indene carbonate) to afford primarily the cyclic carbonate, cis-indene carbonate, has been investigated. Under some conditions, small quantities of the epoxide monomer used in the polycarbonate synthesis, indene oxide, were provided as well. The pathway for production of indene oxide was suppressed in the presence of added carbon dioxide. In all instances, light is required for polycarbonate degradation. The activation energy for depolymerization of poly(indene carbonate) was found to be 189 ± 5.8 kJ mol–1, which is considerably higher than that seen for a variety of other aliphatic polycarbonates. Degradation reactions for poly(indene carbonate) were shown to proceed via a radical pathway which was quenched in the presence of the radical trap, (2,2,6,6-tetramethylpiperidine-1-yl)oxyl (TEMPO).