In recent years, ionic conductive hydrogels have shown great potential for application in flexible sensors, energy storage devices, and actuators. However, developing facile and effective methods for fabricating such hydrogels remains a great challenge, especially for hydrogels that retain their properties in extreme environmental conditions, such as at subzero temperatures or storage in open-air conditions. Herein, a water-miscible ionic liquid (IL), such as 1-ethyl-3-methylimidazolium acetate (EMI-mAc), was introduced to form an IL/water binary solvent system for poly(vinyl alcohol) (PVA) to create ionic conductive PVA hydrogels. The physically crosslinked PVA/EMImAc/H 2 O hydrogels showed better mechanical properties and transparency than the traditional PVA hydrogel prepared by the freeze−thaw method due to the formation of homogeneous and small PVA microcrystals in the EMImAc/H 2 O binary solvent system. More importantly, the PVA/EMImAc/H 2 O hydrogel exhibited significant anti-freezing and water-retaining properties because of the presence of the IL. The hydrogels remained flexible and conductive at temperatures as low as −50 °C and retained more than 90% of their weight after storage in open-air conditions for 2 weeks. In addition, the thermal stability of the hydrogel could be increased to 95 °C through the addition of Mg(II) ions. A multimodal sensor based on the PVA/EMImAc/H 2 O/Mg(II) hydrogel showed high sensitivity and a quick response to changes in pressure, strain, and temperature, with both long-term stability and a wide working temperature range. This study may open a new route for the fabrication of functional PVA-based hydrogel electrolytes and provide a practical pathway for their use in multifunctional electronic and sensory device applications.

A photocurable triple shape memory polymer (TSMP) resin based on acrylic monomers and an ion−pair comonomer (IPC) has been formulated and successfully 3D printed with a digital light processing (DLP) printer. The ion-rich and ion-poor domains produced by polymerizationinduced microphase separation (PIMS) generate two wellseparated glass transition temperatures and an excellent triple shape memory effect in the material, which is systematically studied by dynamic mechanical analysis (DMA) and atomic force microscopy (AFM). With the TSMP resin, an intermediate shape can be set to distinguish and program different shape evolution pathways (SEPs). To visualize the sequential shape shifting, several 3D models are printed and transform through distinct pathways. A potential application of shape memory microfluidics is also demonstrated as a proof-of-concept.

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Perovskite materials have drawn the greatest attention as alternatives for approaching cost-effective perovskite solar cells (PSCs) in the past decade. However, the desire for PSCs with photocurrent hysteresis-free characteristics has been unfulfilled due to the intrinsic foibles of perovskite materials. In this study, PSCs with boosted power conversion efficiency (PCEs), dramatically suppressed photocurrent hysteresis, and significantly boosted stability through one-step self-assembled methylammonium lead iodide (CH 3 NH 3 PbI 3 ) cocrystallized with poly(ethylene oxide) (PEO) are reported. It is found that one-step selfassembled CH 3 NH 3 PbI 3 cocrystallized with PEO could generate high-quality thin film with significantly enlarged crystal grains through weak hydrogen interactions between CH 3 NH 3 PbI 3 and PEO. Further studies demonstrate that one-step self-assembled PEO−CH 3 NH 3 PbI 3 thin films possess improved charge carrier transport, reduced charge carrier recombination, and promoted charge carrier extraction time as compared with those of one-step self-assembled processed CH 3 NH 3 PbI 3 thin film. As a result, PSCs by one-step self-assembled PEO− CH 3 NH 3 PbI 3 thin films exhibit a PCE of 20.78%, which is an over 20% enhancement compared to that (17.42%) from PSCs by onestep self-assembled CH 3 NH 3 PbI 3 thin films. Moreover, PSCs by one-step self-assembled PEO−CH 3 NH 3 PbI 3 thin films exhibit dramatically suppressed photocurrent hysteresis and significantly boosted stability. All these results demonstrate that the method of one-step self-assembled perovskites cocrystallized with polymers is a facile approach toward high-performance PSCs.