(348b) On-Demand Degradation of Bioplastics into Soil-Enriching Compost

Plastics have raised environmental concerns because less than 10% of the generated plastic waste is recycled every year. Plastics that are not recycled accumulate in landfills because they degrade very slowly. Despite these concerns, consumers continue to rely on plastics because they are convenient and versatile: plastics can be easily processed (shaped and molded into a variety of objects); their mechanical properties can be tuned from flexible films to rigid solids; and they offer high strength for a low weight. Alternatives to synthetic plastics have been explored, including bioplastics based on either natural polymers like cellulose or semi-synthetic polymers like polylactic acid (PLA). Products made from these latter materials are technically ‘degradable’ or even ‘compostable’, but they mostly still end up in landfills, where they degrade slowly, if at all. Even if these ‘compostable’ plastics were taken to a commercial composting facility, their biodegradation into compost will occur only if incubated under specific conditions (high temperatures, moist environment) for long times (days or weeks).

In this presentation, we explore a new concept: bioplastics that can be degraded ‘on-demand’ in minutes. We make bioplastics (based on natural polymers) that can be shaped into robust products just like those made from conventional plastics ⎯ including disposable plates and cups, as well as grocery or trash bags. Thus, our bioplastic products will be alternatives to current products for a variety of end-uses. But after their use, we ‘switch on’ the degradation of these bioplastics into small fragments ⎯ for this, we spray the used bioplastic with a solution of hydrogen peroxide (H₂O₂). H₂O₂ is a benign liquid that is used as a disinfecting agent in hospitals. Our central idea is to embed catalysts in the bioplastic film. When the catalyst comes into contact with H₂O₂, a reaction will occur, decomposing H₂O₂ into oxygen (O₂) gas in the form of bubbles. We show that the formation of these gaseous bubbles induces the film to break down into small fragments ⎯ the entire process takes place within minutes at room temperature. The fragments thus formed are benign and non-toxic and can be added to a compost heap, where they can be converted into valuable compost. Our approach represents a sustainable solution to reducing and managing plastic waste.