Development of Nanostructured Films Based on PLA and Chitosan Nanoparticles Generated by Supercritical CO2 Assisted Processes

In this study, supercritical processes were set-up to generate chitosan nanoparticles that were incorporated in biobased PLA films produced by cast extrusion. Firstly, chitosan nanoparticles were generated using two CO2 based processes: (1) Supercritical AntiSolvent process where CO2 acts as an antisolvent towards an acetic acid aqueous solution. Nanoparticles with an average size of 378 nm were obtained. (2) Sc-CO2 assisted solubilisation and atomization process where chitosan was dissolved in CO2 acidified water followed by spray-drying. Dried nanoparticles with a median diameter of 400 nm were generated. These generated nanoparticles and other chitosan particles were dispersed in PLA (2.4% w/w) by cast extrusion using a micro-compounder. The morphology and properties of the resultant nanostructured composite films were studied. Particles dispersion and size distribution within the films were analysed by optical and scanning electron microscopy and showed a good dispersion of the particles with no agglomeration. Differential scanning calorimetry revealed a nucleating effect of the chitosan nanoparticles.