Vapor-induced Crystallization in Alcoholic Sorption using Poly(lactic acid) Films

In this study, the sorption amount of alcohols (ethanol, 1-propanol, and 2-propanol) vapors on poly(lactic acid) (PLA) membrane was measured resulting in high increase in sorption. Sorption amount increases as the molecular volume of vapor decreases in the low-pressure region. The sorption amount of branched 2-propanol is lower than that of linear 1-propanol. In the high-pressure region, the PLA film tends to swell or plasticize as the cluster size increases, thereby increasing sorption. In addition, the alcohol vapor sorbed in the PLA film causes vapor-induced crystallization, which is in contrast to solvent- and thermally-induced crystallization, and forms an unknown crystal structure.