(322e) Biodegradation of Polymer Films and Fibers: Exploring the Role of Surface Coatings

The environmental devastation caused by single-use plastics necessitates the advancement of sustainable materials. Thus, materials that meet both in-use requirements and provide a viable alternative for sustainable disposal must be developed. Biodegradable plastics are a promising solution, as they can undergo biological recycling, where valuable products such as compost and biogas are produced upon disposal. Many biodegradable plastics are available on the market today, including (poly)-lactic acid, or PLA, a polyester derived from renewable biomass. Although PLA is certified as compostable at thermophilic temperatures, current research is predominantly focused on unmodified PLA. However, before integration into consumer products, PLA requires modification to overcome its hydrophobicity and brittleness. Yet, the impact of surface coatings, additives, and blending on PLA biodegradation remains elusive. In this study, we aim to unravel the impact of surface coatings on PLA biodegradation in relation to temperature, oxygen presence, and structure. PLA films and fibers were fabricated and coated with sorbitan monolaurate or polysorbate 20, chosen for their common use as wetting agents in consumer products. The materials were characterized through contact-angle measurements to assess the coating’s impact on wettability and quartz-crystal microbalance to examine adsorption kinetics. Both aerobic and anaerobic biodegradability were studied as a function of temperature, as the material could be treated by composting (aerobic) or disposed of in a landfill or anaerobic digester (anaerobic) at the end-of-life. Carbon dioxide and methane generation were used to quantify aerobic and anaerobic biodegradation, respectively. Additional indicators of biodegradation were also measured throughout the duration of the experiments, including molecular weight, crystallinity, and biofilm thickness. The insights gained from this work will inform the development of sustainable materials with functional moieties for various applications including hygiene products, single-use packaging, and disposable medical devices.