Synthesis of polymandelide: A degradable polylactide derivative with polystyrene-like properties

Polymandelide, an aryl analogue of polylactide, was synthesized by the ring-opening polymerization of mandelide, the cyclic dimer of mandelic acid. The poor solubility of rac-mandelide limited the synthesis of polymandelide via solution polymerization, but polymerization of mandelide at 70 degrees C as a heterogeneous slurry in acetonitrile yielded first-order kinetic plots and polydispersities < 1.2. High molecular weight polymer prepared by melt polymerizations at T > 150 degrees C exhibit properties that mimic those of polystyrene. Polymandelide is a glassy amorphous polymer with a T-g of 100 degrees C, with rheological properties comparable to polystyrene, and thermal gravimetric analyses under nitrogen show that the polymer is stable to similar to 300 degrees C. Racemization during polymerization precluded formation of a crystalline polymer. Degradation of polymandelide in pH 7.4 buffer at 55 degrees C is consistent with a bulk erosion model and, due to its high T-g, proceeds at similar to 1/100 the rate of polylactide under similar conditions.