Three-Dimensional Programmable, Reconfigurable, and Recyclable Biomass Soft Actuators Enabled by Designing an Inverse Opal-Mimetic Structure with Exchangeable Interfacial Crosslinks

Despite the unceasing flourishing of intelligent actuators, it still remains a huge challenge to design mechanically robust soft actuators with the characteristics of three-dimensional (3D) programmability, reconfigurability, and recyclability. Here, we utilize fully bioderived natural polymers to fabricate biomass soft actuators (BioSA) integrating all above features through an ingenious microstructure design. BioSA consists of an interconnected inverse opal-mimetic skeleton of sodium alginate (NaAlg) and a continuous matrix of epoxidized natural rubber (ENR), with exchangeable β-hydroxyl ester linkages at their interfaces. The hydrophilic nature and interconnected structure of the NaAlg skeleton endow BioSA with exceedingly acute humidity response and robust mechanical properties. Meanwhile, the dynamic nature of β-hydroxyl ester linkages enables the design of complex 3D structured soft actuators with reconfigurability and recyclability. Since both ENR and NaAlg are derived from natural resources, and the water-based manufacturing process is extremely facile and environmentally friendly, this work provides a novel strategy to fabricate 3D programmable intelligent actuators with both robust mechanical properties and sustainability.