Silk-Inspired Design and Manufacturing of Robust Plantymers

Plant-derived biopolymers may become sustainable alternatives to fossil-based polymers, yet their poor material performance has so far limited their adoption. Plant-derived biopolymers require careful control over the micro- and nanostructures to tune their mechanical behavior. Silk-spinning as done by spiders is one such mechanism, which combines liquid-liquid phase separation (LLPS) and mechanical force to drive β-sheet formation from α-helical precursor proteins to achieve high strength fibers. We develop a similar processing route combining coacervation resulting from LLPS and mechanical force to enhance maize-derived zein into what we call a “plantymer” material, yielding films and fibers with superior mechanical performance. LLPS of zein is triggered by water-ethanol solvent control, resulting in a protein-rich phase that retains fluidity to enable the shear-induced fabrication of films and fibers, mimicking the strengthening mechanism of silk. The resulting materials demonstrate a rigidity comparable to silk and even exhibit good oxygen and moisture barrier properties. We demonstrate the efficacy of plantymer films in preventing banana browning. Our work highlights how nature-inspired polymer processing routes can lead to simple-yet-effective ways of producing plant-derived biopolymer materials with enhanced performance. Protein-based bioplastics suffer from poor mechanical properties, limiting their use. Here, the authors report a coacervation based processing method for maize-derived zein protein which encourages β-sheet formation through shear-induced alignment, leading to high tensile strength films and fibres.