Stretchable electronics, which can retain their functions under stretching, have attracted great interest in recent decades. Elastic substrates, which bear the applied strain and regulate the strain distribution in circuits, are indispensable components in stretchable electronics. Moreover, the self‐healing property of the substrate is a premise to endow stretchable electronics with the same characteristics, so the device may recover from failure resulting from large and frequent deformations. Therefore, the properties of the elastic substrate are crucial to the overall performance of stretchable devices. Poly(dimethylsiloxane) (PDMS) is widely used as the substrate material for stretchable electronics, not only because of its advantages, which include stable chemical properties, good thermal stability, transparency, and biological compatibility, but also because of its capability of attaining designer functionalities via surface modification and bulk property tailoring. Herein, the strategies for fabricating stretchable electronics on PDMS substrates are summarized, and the influence of the physical and chemical properties of PDMS, including surface chemical status, physical modulus, geometric structures, and self‐healing properties, on the performance of stretchable electronics is discussed. Finally, the challenges and future opportunities of stretchable electronics based on PDMS substrates are considered.

Plastic waste has been increasingly transferred from land into the ocean and has accumulated within the food chain, causing a great threat to the environment and human health, indicating that fabricating an eco‐friendly and biodegradable replacement is urgent. Paper made of cellulose is attractive in terms of its favorable biodegradability, resource abundance, large manufacturing scale, and low material cost, but is usually hindered by its inferior stability against water and poor mechanical strength for plastic replacement. Here, inspired by the reinforcement principle of cellulose and lignin in natural wood, a strong and hydrostable cellulosic material is developed by integrating lignin into the cellulose. Lignin as a reinforced matrix is incorporated to the cellulose fiber scaffold by successive infiltration and mechanical hot‐pressing treatments. The resulting lignin‐cellulose composite exhibits an outstanding isotropic tensile strength of 200 MPa, which is significantly higher than that of conventional cellulose paper (40 MPa) and some commercial petroleum‐based plastics. Additionally, the composite demonstrates a superior wet strength of 50 MPa. Adding lignin also improves the thermostability and UV‐blocking performance of cellulose paper. The demonstrated lignin‐cellulose composite is biodegradable and eco‐friendly with both components from natural wood, which represents a promising alternative that can potentially replace the nonbiodegradable plastics.

materials (e.g., boron nitride (BN), graphene, and MoS 2 ) have great potential in emerging energy, environmental, and electronics applications. Assembly of 2D materials into vertically aligned structures is highly desirable (e.g., low tortuosity for rapid ion transport in fast charging−discharging batteries, guiding thermal transport for efficient thermal management), yet extremely challenging due to the energetically unfavorable in processing. Herein, we reported a general three-dimensional (3D) printing method to fabricate vertically aligned 2D materials in multiscale, using BN nanosheet as the proof-of-concept. The 3D-printed macroscale rods are composed of vertically aligned BN nanosheets at the nanoscale. The formation of the hierarchical aligned structure is enabled by the optimized ink that holds a significant shear-thinning behavior and an ultrahigh storage modulus, as identified at a narrow region in the printability diagram. The resulting vertically aligned multiscale structure with 2D nanosheets demonstrated an outstanding throughplane thermal conductivity, up to 5.65 W m −1 K −1 , significantly higher than the value of conventional BN based structures where the sheets are horizontally aligned. The vertical 3D printing of 2D BN nanosheets can be expanded to other 2D materials in constructing hierarchically aligned structures for a range of emerging technologies such as batteries, membranes, and structural materials.

Postassembly modification strategy has been successfully employed in the construction of discrete metallosupramolecular assemblies. However, the most known reports have been limited to the simple structural conversion through the easy covalent reactions, thus hindering the development of organometallic functional materials. In this study, we first combined coordination-driven self-assembly and postassembly reversible addition-fragmentation chain-transfer (RAFT) polymerization to produce a new family of star supramolecular polymers containing well-defined metallacycles as cores, which featured typical lower critical solution temperature (LCST) behavior in water because of the existence of poly(N-isopropylacrylamide) (PNIPAAM) moieties. Moreover, the obtained star polymers could further form supramolecular hydrogels cross-linked by discrete hexagonal metallacycles at room temperature without heating-cooling process. Interestingly, the resultant polymeric hydrogels exhibited stimuli-responsive behavior toward temperature and bromide anion as well as self-healing property. We demonstrated that the dynamic nature of Pt-N bonds in the hexagonal metallacycles played an important role in determining the stimuli-responsive and self-healing property of the final soft matters. Thus, merging coordination-driven self-assembly and postassembly polymerization provided a new avenue to the preparation of functional materials containing well-defined, discrete metal-organic assemblies as main scaffolds.

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