78721Development of a sustainable, recyclable, and circular Waterproof Breathable TextileClosedCollaborative R&DInnovate UKWaterproof breathable garments typically consist of a laminated multi-layer construction, comprising a durable water-repellent-coated outer shell textile, a waterproof breathable membrane, and a lining material. These fabrics are bonded together to form the multi-layer structure, with pieces of fabric sewn together to produce garments. To prevent leaks along seams, they are sealed with tape. This approach delivers high-performance apparel, but is limited by three key drawbacks: 1\.**Use of environmentally concerning chemicals.** High-performance membranes are typically manufactured from expanded polytetrafluoroethylene (ePTFE; Gore-Tex), which is inherently waterproof, windproof, and chemically inert. However, brands are under increasing consumer pressure to remove PFCs (per- and poly-fluorinated chemicals), since these harmful chemicals persist and bioaccumulate when released in the environment (OECD\_2013). 2\. **No sustainable end-of-life solutions.** Multi-material textiles cannot be separated and face either landfill or incineration at end-of-life. In landfill, plastics break down slowly over time to produce microplastics, which are harmful and persist in the environment (OECD\_2013). During incineration, PTFE membranes used in Waterproof Breathable Textiles (WBTs) have been shown to produce highly toxic hydrofluoric acid, which is converted to fluorspar in a typical municipal incinerator (Aleksandrov\_et\_al\_2019). 3\.**Requirement for cheap labour.** High manual effort associated with garment production means manufacture requires large numbers of fabric cutters and sewing machine operators. China accounts for around 38% by value of the world's textile exports (WTO\_2019). The recent lockdown in Leicester has brought the condition of textile workers closer to home to the fore, with workers reportedly receiving far below UK minimum wage (as little as £3.50/hour) and working in unsafe conditions, with little or no social distancing during lockdown (The\_Sunday\_Times\_2020). Amphibio is a London-based micro-SME founded in November 2018 by Jun Kamei, a designer and material scientist exploring potential commercial applications of wearable superhydrophobic porous membranes. With Innovate UK support, we will develop an innovative WBT that delivers on the triple bottom line of three Ps: People, Planet, and Profit: 1\.**People.** We will develop an automated whole garment manufacturing process using digital 3D knitting, which removes the requirement for cheap labour. Uniqlo launched a 3D knitted collection in 2017 and is now using 3D knitting to produce seamless cotton jumpers. However, 3D knitting has not yet been applied to produce waterproof garments, since existing multi-layer WBTs require traditional cut-and-sew production. Since we produce our WBT from a single material, we can use digital 3D knitting to produce high-performance seamless garments. SHIMA SEIKI's WHOLEGARMENT Mach2XS knitting machine can knit a custom jacket in 90 minutes, delivering an annual production capacity of 5,000+ jackets from a single machine(Los\_Angeles\_Times\_2017). 2\.**Planet.** Our mono-material WBT will be 100% recyclable and PFC-free. In addition, 3D knitting is zero waste. Cut-and-sew production typically leaves about one fifth of fabric on the cutting room floor (EPRS\_2019). 3\.**Profit.** Working with leading British clothing brands, our innovative material will help organisations deliver on their sustainability targets, supporting the UK clothing industry to 'build back better' post-COVID-19\.