Flip-flops are one of the most popular sandals, with an estimated market size of $20 billion.


Polyurethane foams made from algae oil were developed to meet commercial specifications for midsole shoes and the foot-bed of flip-flops. The sustainable, consumer-ready, biodegradable materials are 52 percent bio-content. The foams were tested by immersing them in traditional compost and soil — the materials degraded after just 16 weeks. During the decomposition period, to account for any toxicity, scientists measured every molecule shed from the biodegradable materials and identified the organisms that degraded the foams. The enzymes from the organisms degrading the foams were shown to depolymerize the polyurethane products. The team then identified the intermediate steps that take place in the process. The depolymerized products were isolated and used to synthesize new polyurethane monomers, completing a “bioloop.”


University of California, San Diego

Foot-bed of flip-flops being pulled from a mold. (Photo: Stephen Mayfield, UC San Diego)


The full recyclability of commercial products is the next step in the scientist's mission to address the current production and waste management problems created by plastics — which could result in 13 billion metric tons of plastic in landfills or the natural environment (such as oceans) by 2050.


The foams currently are 52 percent biocontent but the scientists are working towards 100 percent. While commercially on track for production, doing so economically is a matter of scale that the team is working out with their manufacturing partners.

Contact Cynthia Dillon of UC San Diego at This email address is being protected from spambots. You need JavaScript enabled to view it.; 858-822-0142.