Cellulose‐Based Dual‐Network Conductive Hydrogel with Exceptional Adhesion

Abstract

Cellulose consists of a natural, rigid polymer that is widely used to improve the mechanical and water‐holding properties of hydrogels. However, its abundant hydroxyl groups make it highly absorbent to free water, leading to swelling behavior. This increased free water content will also decrease mechanical and adhesive performance. In this study, cellulose is successfully hydrophobically modified to reduce its absorption of free water. Gelatin is then cross‐linked with cellulose through a Schiff‐base reaction, resulting in increased bound water content. This significantly enhances resistance to swelling and permeability, and improves the freeze–thaw stability of the hydrogel. Due to its internal hydrophobicity, water molecules can quickly penetrate into the interior, reducing their residence time on the hydrogel surface. This allows the hydrogel to maintain high adhesion in natural environments, achieving an adhesion strength of up to 3.0 MPa on wood and bamboo‐based materials. The hydrogel can retain its adhesive properties even after prolonged exposure to a humid environment. Additionally, Na+ ions enhance the electrical conductivity and sensitivity of the hydrogel (gauge factor (GF) = 1.51), demonstrating its potential applications in flexible sensing.