Despite extensive progress to engineer hydrogels for a broad range of technologies, practical applications have remained elusive due to their, until recently, poor mechanical properties and lack of fabrication approaches, which constrain active structures to simple geometries. We herein demonstrate a family of ionic composite hydrogels with excellent mechanical properties that can be rapidly 3D-printed at high resolution using commercial stereolithography technology. The new materials design leverages the dynamic and reversible nature of ionic interactions present in the system with the reinforcement ability of nanoparticles. The composite hydrogels combine within a single platform tunable stiffness, toughness, extensibility, and resiliency behavior not reported previously in other engineered hydrogels. In addition to their excellent mechanical performance, the ionic composites exhibit fast gelling under near-UV exposure, remarkable conductivity, and fast osmotically-driven actuation. The design of such ionic composites, which combine a range of tunable properties and can be readily 3D-printed into complex architectures provides opportunities for a variety of practical applications such as artificial tissue, soft actuators, compliant conductors and sensors for soft robotics.

Due to its origin from renewable resources, its biodegradability, and recently, its industrial implementation at low costs, poly(lactide) (PLA) is considered as one of the most promising ecological, bio-sourced and biodegradable plastic materials to potentially and increasingly replace traditional petroleum derived polymers in many commodity and engineering applications. Beside its relatively high rigidity [high tensile strength and modulus compared with many common thermoplastics such as poly(ethylene terephthalate) (PET), high impact poly(styrene) (HIPS) and poly(propylene) (PP)], PLA suffers from an inherent brittleness, which can limit its applications especially where mechanical toughness such as plastic deformation at high impact rates or elongation is required. Therefore, the curve plotting stiffness vs. impact resistance and ductility must be shifted to higher values for PLA-based materials, while being preferably fully bio-based and biodegradable upon the application. This review aims to establish a state of the art focused on the recent progresses and preferably economically viable strategies developed in the literature for significantly improve the mechanical performances of PLA. A particular attention is given to plasticization as well as to impact resistance modification of PLA in the case of (reactive) blending PLA-based systems.

A family of multi-responsive hydrogel-based actuators capable of rapid and controllable motion in response to any immediate environmental change is herein demonstrated towards the 3D-printing of functionally graded structures that are encoded with anisotropic swelling behavior.

We demonstrate a novel family of multi-responsive materials, i.e. nanocomposites built on ionic interactions, that combine enhanced mechanical performances and reversibility endowed to dynamic systems.