The University of California San Diego is developing a new type of biodegradable thermoplastic polyurethane (TPU) commonly utilized in consumer products like footwear and memory foam. The team at Jacobs School of Engineering has introduced a method to integrate bacterial spores into the plastic to enable it to break down at the end of its lifecycle. These spores, derived from a strain of Bacillus subtilis known for its plastic-degrading capabilities, germinate when exposed to certain environmental conditions, such as those found in compost.
This cutting-edge plastic is crafted by feeding Bacillus subtilis spores and TPU pellets into a plastic extruder, where they are mixed and melted at high temperatures to form thin plastic strips. When placed in compost settings, these strips have shown remarkable degradation rates, achieving 90% breakdown within five months, even without the presence of additional microbes. This characteristic is particularly advantageous as it allows the material to degrade in less hospitable environments, not just in ideal composting facilities.
Bacillus subtilis, commonly used in probiotics, is considered quite safe, underscoring its environmental friendliness. The spores, evolutionarily engineered to withstand the extrusion process’s high temperatures, do not threaten human or animal health post-degradation and could even benefit plant health.
Beyond its biodegradability, the innovative TPU exhibits enhanced mechanical properties. The addition of bacterial spores has effectively increased the material’s tensile strength and stretchability, akin to the way rebar reinforces concrete. These improvements open new doors for applications where durability and flexibility are critical.
Looking ahead, the researchers at UC San Diego are aiming to increase production scales, accelerate degradation rates, and expand the range of plastics that can be made biodegradable. Such efforts could revolutionize the production of commercial plastics, offering a sustainable alternative that might significantly reduce the overall environmental footprint.
