Hydrogels are materials consisting in a three-dimensional hydrophilic polymer network swollen by a large amount of water. An efficient strategy to elaborate hydrogels consists in establishing double polymer networks in order to achieve high strengthening effect associated with other properties such as transparency or tailored swelling capacities. In this work, we prepared cellulose nanocrystals (CNC)-based hydrogels with double network architecture. The first network, formed by CNC and xyloglucan (XG), takes advantage of entropic adsorption of XG on the CNC surface while the second network relies on electrostatic interactions between cationic Chitosan (Chi) and anionic CNC. Hydrogels with different compositions were successfully prepared. Their rheological properties, stability and swelling capacities in acidic and alkaline solutions were evaluated. Internal organizations of hydrogels were investigated by fluorescence microscopy after polymer labelling and polarized optical microscopy (POM). Finally, hydrogels demonstrated excellent mechanical properties and tuneable swelling capacities that can be leveraged for the implementation of bilayer actuators. Therefore, we further prepared films composed of two hydrogels layers, each one containing a different XG/CNC ratio. Bilayered films bended in water due to the asymmetric swelling of layers and the extent of bending can be modulated by the XG/CNC ratio.

水凝胶是由大量水溶胀的三维亲水聚合物网络组成的材料。制备水凝胶的有效策略在于建立双聚合物网络，以实现与其他特性相关的高强化效果，例如透明度或定制的溶胀能力。在这项工作中，我们制备了具有双网络结构的基于纤维素纳米晶体 (CNC) 的水凝胶。第一个网络由 CNC 和木葡聚糖 (XG) 形成，利用 XG 在 CNC 表面的熵吸附，而第二个网络依赖于阳离子壳聚糖 (Chi) 和阴离子 CNC 之间的静电相互作用。成功制备了不同组成的水凝胶。它们的流变特性，评估了在酸性和碱性溶液中的稳定性和溶胀能力。在聚合物标记和偏振光学显微镜（POM）之后，通过荧光显微镜研究了水凝胶的内部组织。最后，水凝胶表现出优异的机械性能和可调节的膨胀能力，可用于实施双层致动器。因此，我们进一步制备了由两层水凝胶层组成的薄膜，每一层都含有不同的 XG/CNC 比率。由于层的不对称膨胀，双层薄膜在水中弯曲，弯曲程度可以通过 XG/CNC 比率来调节。水凝胶表现出优异的机械性能和可调节的膨胀能力，可用于实施双层致动器。因此，我们进一步制备了由两层水凝胶层组成的薄膜，每一层都含有不同的 XG/CNC 比率。由于层的不对称膨胀，双层薄膜在水中弯曲，弯曲程度可以通过 XG/CNC 比率来调节。水凝胶表现出优异的机械性能和可调节的膨胀能力，可用于实施双层致动器。因此，我们进一步制备了由两层水凝胶层组成的薄膜，每一层都含有不同的 XG/CNC 比率。由于层的不对称膨胀，双层薄膜在水中弯曲，弯曲程度可以通过 XG/CNC 比率来调节。