Molecular modeling study of the resistance of PLA to hydrolysis based on the blending of PLLA and PDLA

Molecular modeling has been used to explain how the blending of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) affects the resistance of poly(lactide) (PLA) to hydrolysis. Amorphous PLLA/PDLA blends were created using molecular modeling, and the minimum potential energy of the blends before and after hydrolysis were obtained. The 50/50 blend has the greatest resistance to hydrolysis, which agrees with past experiments and is due to its having stronger hydrogen-bonding and dipole-dipole interactions than pure PLLA or PDLA. This is based on the 50/50 blend having more of these interactions and shorter average lengths for the hydrogen-bonds and dipole-dipole interactions compared to pure PLLA and PDLA. Hydrogen-bonding possibly has a greater effect than the dipole-dipole interactions on the resistance to hydrolysis. The change in potential energy for hydrolysis decreases linearly with increasing % PLLA or % PDLA from 0 to 50%.