Flip-flops are the most popular footwear in the world and account for an alarming percentage of plastic waste that ends up in landfills, seashores, and our oceans. Scientists at the University of California, San Diego have spent years solving this problem, and now they have taken another step towards fulfilling this mission. A team of researchers developed polyurethane foam made from algae oil to meet commercial specifications for the midsole and sole of the flip flop. Their research, published in Bioresource Technology Reports, describes the team’s successful development of these environmentally friendly, ready-to-use, biodegradable materials.
A team of researchers developed polyurethane foam made from algae oil to meet commercial specifications for the midsole and sole of the flip flop.
The research was carried out in collaboration between the University of California, San Diego, and Algenesis Materials, a fledgling materials science and technology company. The project was led by graduate student Natasha Gunawan of the laboratories of Professors Michael Burkart (Physics Division) and Stephen Mayfield (Biological Sciences Division) and Marissa Tessman from Algenesis. It is the latest in a series of recent research publications that collectively, Burkart says, offer a complete solution to the plastics problem – at least for polyurethanes (PU).
The document shows that we have commercial grade foam that is naturally biodegradable. After hundreds of formulations, we have finally reached a formulation that meets commercial specifications. These foams are 52% bio-based – in the end, we will achieve 100%.
Stephen Mayfield, Department of Biological Sciences, University of California, San Diego
In addition to formulating the correct commercial grade foam, the researchers worked with Algenesis to not only create the shoe but also decompose it. Scientists have clearly demonstrated that commercial products such as polyesters, bioplastics, and fossil fuel plastics can be biodegradable, but only in the context of laboratory testing or industrial composting.
In fact, scientists have re-developed biomonomer polyurethanes from the ground up to meet the high demands on footwear materials, while theoretically keeping a chemistry suitable for biodegradation. Algae turned out to be one of the monomers. It is on the basis of such materials that scientists have created special biodegradable foams as an alternative to polyurethane.
After testing the foams by immersing them in traditional compost and soil, the team found that the materials had decomposed after just 16 weeks. During the decomposition period, to account for any toxicity, the scientists measured every molecule released from the biodegradable materials. They also identified organisms that degraded the foam.
The full recyclability of commercial products is the next step in the scientists’ current mission to solve current problems in the production and management of plastic waste. If they are not resolved, then by 2050 this will lead to the release of 96 billion tons of plastic in landfills or into the environment.