Lactide-caprolactone copolymers with tuneable barrier properties for packaging applications

Lactide-caprolactone copolymers have been synthetized employing two metallic catalysts, Ph3Bi and SnOct(2). The analysis of the microstructure by NMR reveals that gradient like copolymers are obtained with SnOct(2) catalyst, whereas for Ph3Bi based copolymers the gradient like character is less pronounced. The incorporation of caprolactone reduces the crystallinity degree and the glass transition temperature, leading to a slight increase of the free volume fraction. Thermal properties, free volume fraction and chemical nature of the penetrant are correlated with obtained oxygen and water vapour permeability. It is demonstrated that selecting adequate compositions of lactide-caprolactone copolymers it is possible to broaden the field of biodegradable polymers in packaging applications.