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Cellulose, as the most abundant natural polymer on Earth, has long captured researchers' attention due to its high strength and modulus. Nevertheless, transferring its exceptional mechanical properties to macroscopic 2D and 3D materials poses numerous challenges. This review provides an overview of the research progress in the development of strong cellulose-based materials using both the "bottom-up" and "top-down" approaches. In the "bottom-up" strategy, various forms of regenerated cellulose-based materials and nanocellulose-based high-strength materials assembled by different methods are discussed. Under the "top-down" approach, the focus is on the development of reinforced cellulose-based materials derived from wood, bamboo, rattan and straw. Furthermore, a brief overview of the potential applications fordifferent types of strong cellulose-based materials is given, followed by a concise discussion on future directions. [ABSTRACT FROM AUTHOR]

Conductive hydrogels have emerged as excellent candidate materials for designing and fabricating flexible wearable sensors. However, there are still critical challenges in preparing high-performance, strongly adhesive, and biocompatible hydrogels through robust and green strategies. A central issue is the lack of an efficient, environmentally friendly and adaptable catalytic system for hydrogel construction. Herein, a series of natural polyphenol/Fe3+ nanodots (PPL/Fe3+ NDs) has been developed as nanoreactors to catalyze the self-gelation of vinyl monomers. The NDs could provide confined spaces for electron transfer, achieving an exceptionally high catalytic efficiency. Remarkably, they were effective in promoting the polymerization of vinyl monomers to form hydrogels even at the Fe content as low as 0.13 μg mL−1. The resulting hydrogels exhibited outstanding mechanical properties, excellent adhesive capacity, stable ultraviolet (UV)-shielding ability, and feasible electrical conductivity. These advantages allow the hydrogel as a flexible wearable sensor to monitor various human motions. It is believed that these natural polyphenolic NDs could open up new possibilities for the advancement of conductive hydrogels and contribute to the design and implementation of human–machine interaction devices. [ABSTRACT FROM AUTHOR]

The heavy metal copper is a serious hazard to human health and the environment. It is challenging to develop a highly efficient adsorbent that is easy to prepare, low cost, having large adsorption capacity, and non-polluting to the environment. Herein, an aminated electrospun polyacrylonitrile (PAN) staple fiber was prepared by grafting diethylenetriamine (DETA) after a hydrothermal reaction. DETA possessed numerous amino functional groups, thus providing more adsorption sites and higher adsorption capacity for copper ions (Cu2+). The Cu2+ adsorption behavior of the aminated fiber conformed to the pseudo-second-order kinetic model. It not only possessed high adsorption activity in the pH range of 3.0–6.0 and could reach a high saturated adsorption capacity of 349.65 mg g−1 at high Cu2+ concentrations but also had the ability to reduce the concentration below 1 mg L−1 at low Cu2+ concentrations with a small amount of adsorbent (0.5 mg). After 5 adsorption–desorption experiments, the removal efficiency of Cu2+ was maintained at more than 90%. This aminated PAN fiber is expected to become a candidate material for dealing with Cu2+ pollution. [ABSTRACT FROM AUTHOR]

La–Mn bimetal oxide nanofibers, used as an adsorbent for the defluoridation of water, were synthesized by an electrospinning and heat treatment technology. The La–Mn bimetal oxide nanofiber adsorbent with a specific surface area of 35.064 m2 g−1 displayed a good defluoridation performance. Both the adsorption kinetics and equilibrium for fluoride (F−) uptake onto La–Mn bimetal oxide nanofibers were investigated. The kinetic studies established that the adsorption attained equilibrium at about 90 min, and the PSO kinetic model was ideal for the kinetic data under 20 and 50 mg L−1. The Langmuir maximum F− uptake was computed to be 189.39 mg g−1 at 308 K and pH 3. A thermodynamic study affirmed a feasible, endothermic, spontaneous and entropy driven process of F− adsorption towards La–Mn bimetal oxide nanofibers at the studied temperature range. Except for the competitive adsorption of PO43− and F−, the presence of NO3−, CO32−, Cl− and SO42− had little effect on fluoride removal. The La–Mn bimetal oxide adsorbent exhibited a good reusability. [ABSTRACT FROM AUTHOR]

Flax fibers, with abundant resources and a low cost, are an excellent precursor of carbon fibers for supercapacitors. At present, they are very attractive for designing electrodes with high electrochemical performance via a simple and green way. Hence, we systemically control the specific surface area and pore structure of flax-based carbon fibers by impregnating them with zinc chloride (ZnCl2) solution. The results show that the dehydration and expansion effects of ZnCl2 affect the microstructure, which is directly related to the specific capacitance. After activation, the optimized electrode exhibited the highest specific capacitance of 105 F g−1 at a current density of 1 A g−1, which has been improved by more than 10 times compared to that of pure-flax based carbon fibers. Moreover, they also show an excellent cycling stability of 98.7% after 10 000 cycles, even at a high current density of 10 A g−1. These results further demonstrate that flax-based electrodes have potential to be applied to some relevant energy storage applications in the future. [ABSTRACT FROM AUTHOR]

In recent years, as an energy storage device with a fast charge and discharge speed, long cycle life, and good stability, flexible supercapacitors (SCs) have been extensively used in flexible electronic devices such as smart textiles, flexible display screens, and micro-robots. Combining the advantages of conductive materials and hydrogels, conductive polymer hydrogels have good flexibility, biocompatibility, and adjustable mechanical and electrochemical properties, which enable them to be used as electrolyte or electrode materials for flexible SCs, endowing flexible SCs with various excellent properties and meeting their various working requirements. This paper comprehensively reviews the flexible SCs based on conductive polymer hydrogels, from the design, synthesis and application aspects of conductive polymer hydrogels, the various superior functions (e.g., self-healing, high stretchability and compressibility, high toughness, electrochromic and shape memory) of flexible SCs based on conductive polymer hydrogels to different structures of flexible SCs, including fiber-shaped structures, all-in-one sandwich structures, and in-plane interdigital microstructures. Finally, we summarize the challenges faced by flexible SCs based on conductive polymer hydrogels, which provides new research directions and prospects for future development in this field. [ABSTRACT FROM AUTHOR]

Mechanically strong electrospun nanofibers at high temperature are highly desired in the aerospace industry, high temperature filtration and fire protection clothing. In the present work, highly tough poly(imide-co-benzoxazole) (PI-co-PBO) nanofiber belts with excellent thermal stability, mechanical properties and thermomechanical properties were produced from the highly viscous methoxy-containing polyamic acid (MeO-PAA) solution by electrospinning followed by thermal rearrangement. The chemical structures of the polymer nanofibers and the corresponding thermal rearrangement were confirmed by 1H-NMR, FT-IR and TGA. The mechanical properties and thermomechanical properties were characterized by a tensile test and thermomechanical analysis (TMA). The aligned nanofiber belts heat-treated at 450 °C (ANF-450) had the highest tensile strength of 559 MPa, a modulus of 11.2 GPa and a toughness of 12.0 J g−1, respectively, which were much higher than those of the pure PBO films made by thermal rearrangement. The TMA test showed that the ANF-450 exhibited a high tensile strength retention of 90% and a modulus retention of 94% at a high temperature of 200 °C. These excellent thermomechanical properties make electrospun PI-co-PBO nanofibers promising candidates in high temperature areas. [ABSTRACT FROM AUTHOR]

As a unique structural form, helical structures have a wide range of application prospects. In the field of biology, helical structures are essential for the function of biological macromolecules such as proteins, so the study of helical structures can help to deeply understand life phenomena and develop new biotechnology. In materials science, helical structures can give rise to special physical and chemical properties, such as in the case of spiral nanotubes, helical fibers, etc. , which are expected to be used in energy, environment, medical and other fields. The helical structure also has unique charm and application value in the fields of aesthetics and architecture. In addition, helical fibers have attracted a lot of attention because of their tendrils' vascular geometry and indispensable structural properties. In this paper, the development of helical fibers is briefly reviewed from the aspects of mechanism, synthesis process and application. Due to their good chemical and physical properties, helical fibers have a good application prospect in many fields. Potential problems and future opportunities for helical fibers are also presented for future studies.

Solar-driven vapor generation has emerged as a promising wastewater remediation technology for clean water production. However, the complicated and diversified contaminants in wastewater still restrict its practical applications. Herein, inspired by the melanin in nature, a robust aerogel was facilely fabricated for multifunctional water remediation via a one-pot condensation copolymerization of 5,6-dihydroxyindole and formaldehyde. Benefiting from the superhydrophilicity, underwater superoleophobicity, and synergistic coordination effects, the resulting aerogel not only showed excellent performances in underwater oil resistance and oil-water separation ability, but also removed organic dyes and heavy metal ions contaminants in wastewater simultaneously. Moreover, owing to its admirable light harvesting capacity and porous microstructure for fast water transportation, the aerogel-based evaporator exhibited an excellent evaporation rate of 1.42 kg m -2 h -1 with a 91% evaporation efficiency under 1 sun illumination, which can be reused for long-term water evaporation. Note that such a stable evaporation rate could be maintained even in wastewater containing complex multicomponent contaminants. Outdoor evaporation experiments for lotus pond wastewater under natural sunlight also proved its great potential in practical applications. All those promising features of this all-in-one melanin-inspired aerogel may provide new strategies for the development of robust photothermal devices for multifunctional solar-driven water remediation.