Modulation of flexibility and shape recovery of living Schizophyllum commune pure mycelium material by hydration

Abstract

Pure mycelium materials (PMMs) are novel sustainable materials that could for instance be used as a foam, cellular scaffold, or as an alternative for textile, leather, or meat. Here, mechanical properties of the PMM of the fungus Schizophyllum commune were studied when exposed to different levels of relative humidity (RH) and after submersion in water. Exposure to increasing RH resulted in a more flexible PMM. For instance, exposure to 95 % RH decreased the Young's modulus from 467 to 3.7 MPa and increased elongation at break from 1 % to 18.5 %. Similar properties were found after submersion in water, enabling reshaping the PMM in a mould. Notably, the PMM showed shape memory when it was exposed to cycles of drying in a 90° angled shape, wetting, drying at 180°, and submersion in water. The material reached a mean percentage of shape recovery completeness of 49 %, 55 %, and 66 % in the first, second and third cycle, respectively. The capacity to store and release potential energy was not affected during these cycles. Together, a living PMM with hygromorphic shape memory is described for the first time, which may be used for instance in smart switches or valves.