Dynamic Branching for Circularity (DYNABRANCH)

Current practices in the plastics lifecycle are largely unsustainable, with too large fraction of plastics not being re-used or recycled. Generally, it is very difficult to directly re-use or recycle plastics because use, weathering and re-processing of these materials leads to a deterioration in their properties. This is often caused by a reduction in molar mass and changes in chemical structure of the polymers. Mechanical recycling therefore often leads to materials that can only be used in low-value (and less demanding) applications. We propose a conceptually novel approach that allows recycling of plastic materials over multiple cycles without significant loss in material properties, and commercial functionalities. We propose a slight, but crucial, modification of the molecular structure of the polymer by the introduction of small amounts of dynamic branching points into (normally linear) polycarbonates. This approach should lead to re-processed materials with properties comparable to virgin materials by mitigating the effects of imperfections (molar mass, changed end groups) through bond rearrangements in the re-processing step; the presence of dynamic covalent bonds is imperative to its success. Basing the new materials on existing plastics should benefit from the advantages of drop-in materials, minimising changes in production facilities and supply chains. Our consortium brings together polymer chemists, material engineers, a plastics manufacturer, a consumer behavioural scientist and a strategic business expert, to design and prepare these re-processable plastics, study and compare their properties and ascertain their compatibility with current industrial processes, and to assess their ultimate acceptance by converters, users and consumers.