generation and propagation of cracks, and will directly affect the service life, applicability, reliability and safety of materials. However, high strength and high toughness are mutually exclusive. [1,2] Elastomers as one of the most widely used materials typically have a compromise between strength and toughness, which limits their applications in impact-resistant environments, biomedical devices, soft robotics, wearable electronics, etc. [3][4][5][6][7][8][9] As an effective strategy, increasing the energy dissipation in the structure has been demonstrated to improve the strength and toughness of elastomers. [10][11][12][13][14][15] First, the incorporation of nano-fillers enables the formation of nano-holes in regions off-domain under high strain, while increasing energy dissipation through bridging and entanglement effects. However, this method is limited by the uneven dispersion of nanoparticles due to the commonly poor compatibility with the matrix. [10,11,16,17] Second, a stable and robust covalently crosslinked network can significantly improve the mechanical properties, but the high cross-linking density may limit the slip of the segments which may reduce the material ductility. [18] Most notably, inspired by the structure of a large number of natural materials such as spider silk, [19,20] mussels, [21][22][23] bones [24] and muscle fibers, [25,26] The elastomers with the combination of high strength and high toughness have always been intensively pursued due to their diverse applications. Biomedical applications frequently require elastomers with biodegradability and biocompatibility properties. It remains a great challenge to prepare the biodegradable elastomers with extremely robust mechanical properties for in vivo use. In this report, we present a polyurethane elastomer with unprecedented mechanical properties for the in vivo application as hernia patches, which was obtained by the solvent-free reaction of polycaprolactone (PCL) and isophorone diisocyanate (IPDI) with N,N-bis(2-hydroxyethyl)oxamide (BHO) as the chain extender. Abundant and hierarchical hydrogen-bonding interactions inside the elastomers hinder the crystallization of PCL segments and facilitate the formation of uniformly distributed hard phase microdomains, which miraculously realize the extremely high strength and toughness with the fracture strength of 92.2 MPa and true stress of 1.9 GPa, while maintaining the elongation-at-break of ≈1900% and ultrahigh toughness of 480.2 MJ m −3 with the unprecedented fracture energy of 322.2 kJ m −2 . Hernia patches made from the elastomer via 3D printing technology exhibit outstanding mechanical properties, biocompatibility, and biodegradability. The robust and biodegradable elastomers demonstrate considerable potentials for in vivo applications.

Development and understanding of antifreezing materials are fundamentally and practically important for materials design and delivery. However, almost all of antifreezing materials are either organic/icephobic materials containing no water or hydrophilic hydrogels containing antifreezing additives. Here, a general crosslinking strategy to fabricate a family of EGINA‐crosslinked double‐network hydrogels with intrinsic, built‐in antifreezing and mechanical properties, but without any antifreezing additives is proposed and demonstrated. The resultant hydrogels, despite large structural and compositional variations of hydrophilies, electrolytes, zwitterions, and macromolecules of polymer chains, achieved strong antifreezing and mechanical properties in different environments including solution state, gel state, and hydrogel/solid interfaces. Such general antifreezing property of EGINA‐crosslinked hydrogels, regardless network compositions, is likely stemmed from their highly hydrophilic and tightly crosslinked DN structures for inducing strong water–network bindings to prevent ice crystal formation from free waters in hydrogel networks. EGINA‐crosslinked hydrogels can also serve as a key component to be fabricated into smart windows with high optical transmittance and supercapacitors with excellent electrochemical stability at subzero temperatures. This work provides a simple, blueprint antifreezing design concept and a family of antifreezing hydrogels for the better understanding of the composite–structure–property relationship of antifreezing materials and the fundamentals of confined water in wet soft materials.

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Perovskite photovoltaics (PPVs) using three-dimensional (3D) perovskites incorporated with two-dimensional (2D) perovskites have drawn great concentration in both academic and industrial sectors. Here, we report high performance of PPVs based on the 2D/3D perovskite bilayer thin film post-annealed with solvent vapor. The 2D/3D perovskite bilayer thin film post-annealed with solvent vapor possesses enlarged crystal size and crystallinity and blue-shifted photoluminescence compared to a 3D MAPbI 3 thin film. Moreover, compared to the PPVs based on a 3D perovskite thin film, enlarged built-in potential, suppressed charge carrier recombination, boosted charge transport, and reduced charge carrier extraction time are observed from the PPVs based on the 2D/3D perovskite bilayer thin film post-annealed with solvent vapor. As a result, perovskite solar cells exhibit a power conversion efficiency of 22.13% and dramatically enhanced stability, and perovskite photodetectors show a photoresponsivity of 1.38 AW −1 , detectivity of 6.52 × 10 14 cm Hz 1/2 W −1 , and linear dynamic range of over 167 dB at room temperature. These results demonstrate that we develop a simple method to approach high-performance PPVs by the 2D/3D perovskite bilayer thin film.