Nanocellulose-mediated transparent high strength conductive hydrogel based on in-situ formed polypyrrole nanofibrils as a multimodal sensor.

A simple method was provided to prepare a transparent, highly conductive, mechanically reinforced, stretchable, and compressible hydrogel. In this system, pyrrole (Py) monomers were gently polymerized and uniformly deposited on the surface of cellulose nanofiber (CNF) via the improved in-situ polymerization. In the opaque PPy@CNF suspension, acrylamide monomers (AM) were dissolved and radical-polymerized to construct the PPy@CNF-PAM hydrogel with the in-situ formation of PPy nanofibrils in the presence of excess ammonium persulfate (APS). The in-situ formed PPy nanofibrils were well intertwined with the CNF and PAM chains, and a highly conductive path was established and permitted visible light to pass through. The amphipathic CNF took along and dispersed PPy aggregates well, and reinforced the hydrogel after formation of PPy nanofibrils. In view of the improved mechanical compressive, stretchable properties and excellent electrical conductivity (4.5 S/m), the resulting hydrogels could serve as a potential electrical device in a range of applications.