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Thermochromic smart windows are considered to be promising energy-saving devices for reducing energy consumption in buildings. The ideal materials for thermochromic smart windows should have high transmittance, high solar modulation, low phase-transition temperature, and excellent high-temperature thermal stability, which are difficult to achieve simultaneously. This work reports a simple one-step low-temperature polymerization method to prepare a thermo-responsive poly(N-isopropylacrylamide)/hydroxypropylmethyl cellulose (PNIPAM/HPMC) hydrogel achieving the above performances simultaneously. The low-temperature polymerization environment endowed the hydrogel with a high luminous transmittance (Tlum) of 90.82%. HPMC as a functional material effectively enhanced the mechanical properties and thermal stability of the hydrogel. Meanwhile, the PNIPAM/HPMC hydrogel showed a low phase-transition temperature (∼32 °C) and high solar modulation (ΔTsol= 81.52%), which proved that it is an ideal material for thermochromic smart windows. Moreover, a PNIPAM/HPMC smart window exhibited high light transmittance (T380–760= 86.27%), excellent light modulation (ΔT365= 74.27%, ΔT380–760= 86.17%, and ΔT940= 63.93%), good indoor temperature regulation ability and stability, which indicated that it was an attractive candidate for application in reducing energy consumption in buildings. This work also provides an option and direction for modifying PNIPAM-based thermochromic smart windows.

The in-situ polymerization of 1,3-dioxolane (PDOL) in battery cells has attracted extensive attention, however, the differences of Lewis acid initiators on the DOL monomer conversion (C%) and electrochemical properties has been ignored. Here, it is demonstrated that compare with Sn(OTf)2Lewis acid initiator, the gelation of DOL is achieved at the lower addition of In(OTf)3. By optimizing their content in the gelation process, their C% are comparable which are 95.7 % and 93.5 % for In(OTf)3and Sn(OTf)2, respectively. However, the higher ionic conductivity (7.1 × 10−4 S cm−1at room temperature), electrochemical window (~4.5 V) and Li+transference number (0.42) are obtained for DOL initiated with In(OTf)3, due to its lower molecular weight which is helpful to the intermolecular Li+transport along PDOL main chain; In addition, the Li/Li symmetrical cell of In(OTf)3can be stably cycled for >500 h at 3 mA cm−2, with an over-potential of 178mv. The storage and cycling impedances of half cells further proves the stable interface of In(OTf)3initiated DOL toward to lithium metal in comparison with those of Sn(OTf)2. Scanning electron microscopy results show a denser and thinner interface in the DOL catalyzed by In(OTf)3. Finally, the assembled Li/LiFePO4battery delivers specific discharge capacity and capacity retention rates of 115.5mAh g−1and 85 %, respectively after 300 cycles at 1C. Through the initiator selection, the DOL synthesis and electrochemical properties can be tuned, which further broadens the design idea of PDOL based solid polymer electrolyte.

1,3-dioxolane (DOL) shows low interfacial impedance and high Coulombic efficiency, thus its polymer electrolytes have attracted extensive attention. In order to initiate DOL polymerization, catalyst amount of LiPF6is usually used rather than as the main lithium salt. Totally replacement of LiTFSI with low cost of LiPF6could bring the heat explosion and high viscosity when mixing DOL with 0.9 M LiPF6electrolyte (carbonate ester solvent). Here, based on the Lewis acid-base interaction, a new type of Lewis base, pyridine, is added to control the explosive polymerization of 1,3-dioxolane in LiPF6electrolyte. Through tuning the pyridine content, the gelling process and electrochemical properties could be controlled. It is demonstrated that the optimized monomer conversion and electrochemical window are up to 85.2 % and 4.6 V; meanwhile, the optimized conductivity and transfer number are 0.99 × 10−3 S/cm (25 °C) and 0.68, respectively. The stable interface between PDOL and lithium metal anode could be proved by the stable over-potential (50mv, 700 h) at current density of 0.5 mA cm−2. After 500 cycles at 2C, the assembled Li/PDOL@py0.125/LiFePO4battery delivers 115 mAh/g and 90 % capacity retention, with high average Coulombic efficiency of 99.83 %. The present results demonstrate the heat suppression role of pyridine toward mixing DOL with 0.9 M LiPF6electrolyte, which solves the heat and viscosity problems for PDOL based gelling polymer electrolytes.

Separator is one of the important elements of lithium-ion batteries, which affects both the capacity and safety performance of the batteries. In this paper, polypyrrole (PPy) was grown on bacterial cellulose (BC) nanofibers using in situ polymerization. A bilayered composite separator with PPy-coated BC conductive upper layer and BC insulating lower layer was prepared by paper-making method. The redox-active PPy could contribute to a specific discharge capacity of 119 mAh g−1at 2C current density for the battery with the bilayered separator, which is significantly superior to the device with the polyolefin separator (73 mAh g−1). Moreover, the redox layer provided a low overpotential in the Li//Li symmetric cell cycle, which played an important role for the cycle stability of the lithium-ion batteries.

Commercial or clinical tissue adhesives are currently limited due to their weak bonding strength on wet biological tissue surface, low biological compatibility, and slow adhesion formation. Although catechol-modified hyaluronic acid (HA) adhesives are developed, they suffer from limitations: insufficient adhesiveness and overfast degradation, attributed to low substitution of catechol groups. In this study, we demonstrate a simple and efficient strategy to prepare mussel-inspired HA hydrogel adhesives with improved degree of substitution of catechol groups. Because of the significantly increased grafting ratio of catechol groups, dopamine-conjugated dialdehyde–HA (DAHA) hydrogels exhibit excellent tissue adhesion performance (i.e., adhesive strength of 90.0 ± 6.7 kPa), which are significantly higher than those found in dopamine-conjugated HA hydrogels (∼10 kPa), photo-cross-linkable HA hydrogels (∼13 kPa), or commercially available fibrin glues (2–40 kPa). At the same time, their maximum adhesion energy is 384.6 ± 26.0 J m–2, which also is 40–400-fold, 2–40-fold, and ∼8-fold higher than those of the mussel-based adhesive, cyanoacrylate, and fibrin glues, respectively. Moreover, the hydrogels can gel rapidly within 60 s and have a tunable degradation suitable for tissue regeneration. Together with their cytocompatibility and good cell adhesion, they are promising materials as new biological adhesives.