Poly(phenyllactide): Synthesis, characterization, and hydrolytic degradation

Poly(phenyllactide) was synthesized via the ring-opening polymerization of phenyllactide, the dimer of phenyllactic acid. Phenyllactide was synthesized by two methods, the solution phase condensation of L-phenyllactic acid and by thermal cracking of low molecular weight phenyllactic acid oligomers. The poor solubility of the monomer limited solution polymerizations of phenyllactide to low yields and low molecular weights, but melt polymerization of phenyllactide with Sn(Oct)(2)/tert-butylbenzyl alcohol at 180 degreesC gave high molecular weight polymers in high yields. The resulting polymers were amorphous due to epimerization of approximate to10% of the stereocenters during polymerization. Poly(phenyllactide) has a glass transition temperature of 50 degreesC and degrades to monomer at 320 degreesC. Experiments run at 55 degreesC at pH 7.4 show that poly(phenyllactide) degrades at similar to(1)/(5) the rate of rac-polylactide.