Chemically modified bacterial cellulose-mediated fiber salting-out method for preparing tough hydrogels

Bacterial cellulose (BC) is employed as a toughening agent in the preparation of composite hydrogels. However, achieving both high strength and toughness after incorporating BC into hydrogels remains challenging. Insufficient amounts of BC limit the enhancement of strength, whereas excessive BC results in reduced elongation of hydrogels. Herein, a fiber salting-out method was developed to fabricate BC/polyvinyl alcohol (PVA) hydrogels by modifying BC with Hofmeister series ions (-COO^-, -PO₃^2-, -SO₃^-). Through the fiber salting-out effect of BC, PVA was induced to aggregate on the BC surface, forming more crystalline domains and thereby improving the mechanical properties of the hydrogels. Among them, the tensile strength and toughness of the SBCP hydrogel (BC modified with -SO₃^-) reached the highest values, measuring 2.98 MPa and 27.48 MJ m^-3, respectively-representing 9-fold and 36-fold increases over those of pure PVA hydrogels. Furthermore, this hydrogel exhibits high electrical conductivity and favorable biocompatibility. This study presents a new strategy for fabricating tough BC-based hydrogels and provides insight into new applications for BC fibers.