Polylactic acid (PLA) resin has been attracting more and more attention because it is not only a biomass-based carbon-neutral material, which does not increase CO2 emission, but also an eco-friendly biodegradable plastic, although the mechanical strength and biodegradability of PLA is not very high. So, by using Chemicals Informatics (CI) based on public literature data, additives effective for improving the mechanical strength and biodegradability of the PLA resin were explored in order to make the PLA resin available for wider use. As a result, adipic acid and 3,3'-dithiodipropionic acid were discovered as effective additives. To clarify the mechanism that improves the mechanical strength and biodegradability with these additives, molecular simulations were conducted. As a result of the simulation, it was found that the lattice matching between PLA and the additives (adipic acid and 3,3'-dithiodipropionic acid) is very good and that this lattice matching increases adhesion between PLA and the additives and improves the mechanical strength. It was also found that the lattice matching constructs the diffusion path of water molecules and enhances the hydrolysis, which accelerates the biodegradability. The effects of the additives were confirmed by tensile testing and hydrolysis tests.
