BioCir® Flex Returns to Stella McCartney’s S.WAVE Collection
From its Fall 2025 debut to its return for Fall 2026 and planned inclusion in Winter 2026, BioCir® Flex shows how next-generation materials can move beyond a first launch into continued commercial adoption.
Developing better plastics means creating materials that brands can use repeatedly, with the performance and consistency their products demand. Balena’s ongoing collaboration with Stella McCartney brings that ambition into focus. Following its debut in the Fall 2025 S.WAVE collection, our proprietary BioCir® Flex material returns for Fall 2026, with further inclusion planned for Winter 2026. Its continued use marks another step in bringing material innovation into commercial footwear.
Now available to shop online here
Innovation Starts at the Sole
A footwear sole faces constant demands. It needs to absorb repeated impact, withstand flexing and abrasion, and deliver reliable grip while remaining comfortable. Meeting these requirements has traditionally involved fossil-based polymers and complex material combinations that can be difficult to manage at end of life.
BioCir® Flex brings a different approach to this demanding component. Balena’s flexible bio-based elastomer combines durability, flexibility and resilience with consideration for material safety and end-of-life pathways. The material is REACH and RoHS compliant and has been tested against AFIRM RSL and EN 71-3 requirements. These credentials help brands assess restricted substances alongside the technical demands of their applications.
Rethinking How Plastics Are Made
Balena is a material science company creating the next generation of plastics for the products we wear, live and play with. Our approach brings together feedstock selection, formulation expertise and technology to develop materials around three priorities: safety, performance and clear end-of-life pathways. No single ingredient defines a Balena material. Performance comes from how every element of the formulation works together.
For highly flexible applications such as footwear, the challenge is to increase the use of renewable feedstocks and reduce fossil dependency while maintaining the properties required for everyday use. BioCir® Flex reflects our work to meet those demands with materials engineered for industrial scale.
Considering What Comes After Wear
Footwear’s complexity extends beyond its construction. Combining polymers, foams, adhesives and textiles can make components difficult to separate and recycle once a shoe reaches the end of its useful life. Addressing that challenge begins with material design.
BioCir® Flex is designed with end-of-life pathways that include recycling and industrial composting under specified conditions. Realising those pathways depends on the finished component, collection systems and access to suitable processing facilities.
By considering these factors alongside performance from the outset, Balena helps brands make more informed material choices for both the use phase and what comes afterwards.
About BioCir® Flex
BioCir® Flex is Balena’s high-performance flexible elastomer, developed as an alternative to conventional TPU and rubber-based materials. Its formulations incorporate renewable bio-based feedstocks, including castor beans, plant oils and polysaccharides, to deliver the durability, flexibility and resilience required for demanding applications.
Its return to Stella McCartney’s S.WAVE collection demonstrates the potential for material science and creative vision to translate into continued commercial use, bringing the next generation of plastics into products people wear.
