Enhanced photodegradation of TiO2-containing poly(epsilon-caprolactone)/poly(lactic acid) blends

The calamitous accumulation of plastic waste in the environment, especially single-use disposables, calls for new approaches to materials design. One method to address the persistence of plastics beyond their intended use is to impart them with functionalities that will either allow for their recyclability or their degradation to basic natural components. This work focuses on the fabrication of photodegradable polyester blends and investigates the impact of compatibilization on photodegradation rates. Specifically, we blended poly(epsilon-caprolactone) (PCL) and poly(lactic acid) (PLA) polymers by (reactive) extrusion in the presence or absence of dicumyl peroxide (DCP), a radical generator, and titanium dioxide (TiO2), an inorganic photocatalyst. We examined the effects of DCP and TiO2 loadings as well as copolymer composition on the thermomechanical properties, photodegradability, and morphology. We found that the inclusion of TiO2 dramatically increased flexural moduli and photodegradation rates in both dry and wet conditions, while reactive compatibilization had little effect of the tested properties. This simple and scalable approach is promising to fabricate materials that can readily photodegrade.