Ammonolysis of Polycarbonates with (Supercritical) Ammonia: An alternative for Chemical Recycling

Ammonolysis of aliphatic and aromatic polycarbonates in liquid or in supercritical ammonia has been studied. Reaction products are alcohols (phenols) and urea. Ammonolysis of bisphenol A polycarbonate (BPA-PC) proceeds at room temperature at a high rate depending on the size and surface of particles. BPA-PC in composites like compact discs or car windows, consisting of a sandwich of glass layers bounded with a polyurethane adhesive to a polycarbonate, can be selectively ammonolyzed. Aliphatic poly(1,6-hexanediyl carbonate) can be fractionated without ammonolytic degradation in liquid ammonia up to 100 °C while ammonolysis occurs under supercritical conditions. If residence time and temperature (rate of reaction) are properly adjusted controlled degradation to oligomers is possible.