Preparation of Flexible, Highly Transparent, Cross-Linked Cellulose Thin Film with High Mechanical Strength and Low Coefficient of Thermal Expansion

The development of next generation of flexible electronic devices requires new materials to replace the glass as transparent windows. Here, flexible, transparent, and very strong cross-linked celluloses have been prepared by cross-linking free cellulose chains with epichlorohydrin (ECH) in its aqueous solution. Atomic force microscopy (AFM), light transmittance, differential thermogravimetric (DTG) thermal analyses, and tensile tests revealed that the as-prepared films are a thickness of about 10 mu m with highly optical transparency and mechanical strength. The film also showed a low coefficient of thermal expansion (CTE) of about 6.9 ppm/K, which is superior to that of glass. Then the as-prepared cellulose film was combined with a dried foam ultrathin film of reduced graphene oxide to prepare a new, flexible, transparent, very strong, and electrically conductive thin film.