Polyglyceryl-4 caprate and polyglycerol-3 provide low mobility and enhance ductility in Schizophyllum commune mycelium materials

Mycelium materials are an emerging class of bio-based fabrics. While the raw material typically exhibits poor elongation at break of 1–2 %, the addition of glycerol as a plasticizer can improve elongation at break up to 29.6 %. However, glycerol is prone to migration due to its small molecular size. This can cause it to move both within and outside the material, which negatively affects the mechanical properties of the material. To address this issue, films of Schizophyllum commune mycelium were treated with various plasticizers, including polyols, non-ionic and anionic surfactants, fatty acid esters, and polyether polyols. Among these, the biodegradable plasticizers polyglyceryl-4 caprate (PGFE-4) and polyglycerol-3 (PG-3) demonstrated the best results, either matching or surpassing glycerol in terms of elongation at break, while exhibiting less migration. The most notable improvements in elongation at break were observed with 4 % PGFE-4, 16 % PG-3, and 16 % glycerol, yielding values of 25.3 %, 24.9 %, and 17.7 %, respectively. Compared to glycerol, plasticizer migration was reduced by up to 11.5-fold with PGFE-4 and 1.8-fold with PG-3. In conclusion, PGFE-4 and PG-3 offer superior alternatives to glycerol, as they reduce migration, contributing to better material stability, and can enhance mechanical properties of the mycelium.