Spectroscopic study on water diffusion in poly(lactic acid) film

Abstract

The diffusion of water in biocompatible semicrystalline poly(lactic acid) (PLA) is investigated using time-resolved ATR-FTIR. There are three different states of water molecules diffusing into the film. Using a 2D correlation analysis, the diffusion process and the role of different functional groups on diffusion is obtained. First, the moderately strongly bound water forms a hydrogen bond with –CO. Then, the water diffuses into free volume (microvoids) and strong hydrogen bonds are formed between two –CO groups and water. The conformations of semicrystalline PLA change during the diffusion process and recover after re-drying. In addition, water first interacts with amorphous segments and then interacts with crystalline segments.