In Situ Growth of Highly Compatible Cu2O-GO Hybrids Via Amino-Modification for Melt-Spun Efficient Antibacterial Polyamide 6 Fibers.

Polyamide 6 (PA6) fiber has the advantages of high strength and good wear resistance. However, it is still challenging to effectively load inorganic antibacterial agents into polymer substrates without antimicrobial activity. In this work, graphene oxide is used as a carrier, which is modified with an aminosilane coupling agent (AEAPTMS) to enhance the compatibility and antimicrobial properties of the inorganic material, as well as to improve its thermal stability in a high-temperature melting environment. Cuprous oxide-loaded aminated grapheme (Cu2O-GO-NH2) is constructed by in situ growth method, and further PA6/Cu2O-GO-NH2 fibers are prepared by in situ polymerization. The composite fiber has excellent washing resistance. After 50 times of washing, its bactericidal rates against Bacillus subtilis and Escherichia coli are 98.85% and 99.99%, respectively. In addition, the enhanced compatibility of Cu2O-GO-NH2 with the PA6 matrix improves the orientation and crystallinity of the composite fibers. Compared with PA6/Cu2O-GO fibers, the fracture strength of PA6/Cu2O-GO-NH2 fibers increases from 3.0 to 4.2 cN/dtex when the addition of Cu2O-GO-NH2 is 0.2 wt%. Chemical modification and in situ concepts help to improve the compatibility of inorganic antimicrobial agents with organic polymers, which can be applied to the development of medical textiles.

A Flexible Long-Wave Infrared Radiation Modulator Integrated with Electrochromic Behavior for Dual-Band Camouflage.

Electrochromic devices (ECDs), which are capable of modulating optical properties in the visible and long-wave infrared (LWIR) spectra under applied voltage, are of great significance for military camouflage. However, there are a few materials that can modulate dual frequency bands. In addition, the complex and specialized structural design of dual-band ECDs poses significant challenges. Here, we propose a novel approach for a bendable ECD capable of modulating LWIR radiation and displaying multiple colors. Notably, it eliminates the need for a porous electrode or a grid electrode, thereby improving both the response speed and fabrication feasibility. The device employs multiwalled carbon nanotubes (MWCNTs) as both the transparent electrode and the LWIR modulator, polyaniline (PANI) as the electrochromic layer, and ionic liquids (HMIM[TFSI]) as the electrolyte. The ECD is able to reduce its infrared emissivity (Δε = 0.23) in a short time (resulting in a drop in infrared temperature from 50 to 44 °C) within a mere duration of 0.78 ± 0.07 s while changing its color from green to yellow within 3 s when a positive voltage of 4 V is applied. In addition, it exhibits excellent flexibility, even under bending conditions. This simplified structure provides opportunities for applications such as wearable adaptive camouflage and multispectral displays.

A Skin-Inspired Self-Adaptive System for Temperature Control During Dynamic Wound Healing.

The thermoregulating function of skin that is capable of maintaining body temperature within a thermostatic state is critical. However, patients suffering from skin damage are struggling with the surrounding scene and situational awareness. Here, we report an interactive self-regulation electronic system by mimicking the human thermos-reception system. The skin-inspired self-adaptive system is composed of two highly sensitive thermistors (thermal-response composite materials), and a low-power temperature control unit (Laser-induced graphene array). The biomimetic skin can realize self-adjusting in the range of 35-42 °C, which is around physiological temperature. This thermoregulation system also contributed to skin barrier formation and wound healing. Across wound models, the treatment group healed ~ 10% more rapidly compared with the control group, and showed reduced inflammation, thus enhancing skin tissue regeneration. The skin-inspired self-adaptive system holds substantial promise for next-generation robotic and medical devices.

Closed-Loop Polymer-to-Polymer Upcycling of Waste Poly (Ethylene Terephthalate) into Biodegradable and Programmable Materials.

Poly(ethylene terephthalate) (PET), extensively employed in bottles, film, and fiber manufacture, has generated persistent environmental contamination due to its non-degradable nature. The resolution of this issue requires the conversion of waste PET into valuable products, often achieved through depolymerization into monomers. However, the laborious purification procedures involved in the extraction of monomers pose challenges and constraints on the complete utilization of PET. Herein, a strategy is demonstrated for the polymer-to-polymer upcycling of waste PET into high-value biodegradable and programmable materials named PEXT. This process involves reversible transesterifications dependent on ester bonds, wherein commercially available X-monomers from aliphatic diacids and diols are introduced, utilizing existing industrial equipment for complete PET utilization. PEXT features a programmable molecular structure, delivering tailored mechanical, thermal, and biodegradation performance. Notably, PEXT exhibits superior mechanical performance, with a maximal elongation at break of 3419.2 % and a toughness of 270.79 MJ m-3. These characteristics make PEXT suitable for numerous applications, including shape-memory materials, transparent films, and fracture-resistant stretchable components. Significantly, PEXT allows closed-loop recycling within specific biodegradable analogs by reprograming PET or X-monomers. This strategy not only offers cost-effective advantages in large-scale upcycling of waste PET into advanced materials but also demonstrates its enormous prospect in environmental conservation.

Highly conductive and porous lignin-derived carbon fibers.

Bio-based carbon fibers derived from lignin have gained significant attention due to their diverse and renewable sources, ease of extraction, and low cost. However, the current limitations of low specific surface area and insufficient electrical conductivity hinder the widespread application of lignin-derived carbon fibers (LCFs). In this work, highly conductive and porous LCFs are developed through melt-blowing, pretreatment, and carbonization processes. The effects of the carbonization temperature and heating rate on the structures and properties of the LCFs are systematically investigated. The resultant LCFs exhibit high electrical conductivity (71 400 S m-1) and a large specific surface area (923 m2 g-1). The assembled lithium-ion battery based on the LCF anodes demonstrates a long cycle life of >800 cycles and a high specific capacity of 466 mA h g-1. The findings of this study hold practical significance for promoting the utilization of lignin in the fields of energy storage, adsorption, and beyond.

Nickel cobaltite nanowire arrays grown on nitrogen-doped carbon nanotube fiber fabric for high-performance flexible supercapacitors.

Flexible supercapacitors have received considerable attention for their potential application in flexible electronics, but usually suffer from relatively low energy density. Developing flexible electrodes with high capacitance and constructing asymmetric supercapacitors with large potential window has been considered as the most effective approach to achieve high energy density. Here, a flexible electrode with nickel cobaltite (NiCo2O4) nanowire arrays on nitrogen (N)-doped carbon nanotube fiber fabric (denoted as CNTFF and NCNTFF, respectively) was designed and fabricated through a facile hydrothermal growth and heat treatment process. The obtained NCNTFF-NiCo2O4 delivered a high capacitance of 2430.5 mF cm-2 at 2 mA cm-2, a good rate capability of 62.1 % capacitance retention even at 100 mA cm-2 and a stable cycling performance of 85.2 % capacitance retention after 10,000 cycles. Moreover, the asymmetric supercapacitor constructed with NCNTFF-NiCo2O4 as positive electrode and activated CNTFF as negative electrode exhibited a combination of high capacitance (883.6 mF cm-2 at 2 mA cm-2), high energy density (241 µW h cm-2) and high power density (80175.1 µW cm-2). This device also had a long cycle life after 10,000 cycles and good mechanical flexibility under bending conditions. Our work provides a new perspective on constructing high-performance flexible supercapacitors for flexible electronics.

Improved photocatalytic property of lignin-derived carbon nanofibers through catalyst synergy.

Converting lignin into high value-added products is essential to reduce our dependence on petroleum resources and protect our environment. In this work, TiO2 and g-C3N4 are loaded in the lignin-derived carbon nanofibers (LCNFs) and an efficient LCNFs-based photocatalytic material (TiO2/g-C3N4@LCNFs) is developed. The spinnability of lignin solution, the chemical structure and morphology of the LCNFs, and the catalytic degradation property of the TiO2/g-C3N4@LCNFs for Rhodamine B (RhB) are systematically investigated. The TiO2/g-C3N4@LCNFs achieve a 92.76 % degradation rate of RhB under UV-vis irradiation, which is close to or higher than most reported carbon fiber-based photocatalysts. The excellent degradation property of the photocatalysts can be ascribed to the synergy of TiO2 and g-C3N4, which improves the excitation efficiency of electron and hole, and prolongs the lifetime of electron-hole pairs. We envision that our work will provide some guidance for the development of efficient photocatalysts based on biomass-derived fiber materials.

Piezoresistive Fibers with Large Working Factors for Strain Sensing Applications.

Piezoresistive fibers with large working factors remain of great interest for strain sensing applications involving large strains, yet difficult to achieve. Here, we produced strain-sensitive fibers with large working factors by dip-coating nanocomposite piezoresistive inks on surface-modified polyether block amide (PEBA) fibers. Surface modification of neat PEBA fibers was carried out with polydopamine (PDA) while nanocomposite conductive inks consisted of styrene-ethylene-butylene-styrene (SEBS) elastomer and carbon black (CB). As such, the deposition of piezoresistive coatings was enabled through nonconventional hydrogen-bonding interactions. The resultant fibers demonstrated well-defined piezoresistive linear relationships, which increased with CB filler loading in SEBS. In addition, gauge factors decreased with increasing CB mass fractions from ∼15 to ∼7. Furthermore, we used the fatigue theory to predict the endurance limit (Ce) of our fibers toward resistance signal stability. Such a piezoresistive performance allowed us to explore the application of our fibers as strain sensors for monitoring the movement of finger joints.

Lignin-based carbon fibers: Insight into structural evolution from lignin pretreatment, fiber forming, to pre-oxidation and carbonization.

Lignin remains the second abundant source of renewable carbon with an aromatic structure. However, most of the lignin is burnt directly for power generation, with an effective utilization rate of <2 %, making value addition on lignin an urgent requirement. From this perspective, preparation of lignin-based carbon fibers has been widely studied as an effective way to increase value addition on lignin. However, lignin species are diverse and complex in structure, and the pathway that enables changes in lignin structure during pretreatment, fiber formation, stabilization, and carbonization is still uncertain. In this review, we condense the common structural evolution route from the previous studies, which can serve as a guide towards engineered lignin carbon fibers with high performance properties.

Melt-spun bio-based PLA-co-PET copolyester fibers with tunable properties: Synergistic effects of chemical structure and drawing process.

The fabrication of bio-based copolyester fiber with adjustable crystallization, orientation structure and mechanical property still remains a great challenge. In this study, a series of copolyester fibers based on terephthalic acid (PTA), ethylene glycol (EG) and l-Lactide (L-LA) were prepared via melt copolymerization and spinning. The resultant PLA-co-PET (PETLA) fibers exhibited tunable structure and property due to the synergistic effects of chemical structure and drawing process. The chemical structure of PETLA was confirmed by NMR, FTIR and XRD, which suggested that the random degree of copolymer increased with LA content and the viscosity decreased with the increase of LA content. The crystallization behavior, melting characteristic, thermal stability and rheological property were investigated by DSC, TGA and rheometer, the results indicated that all the PETLA exhibited the crystallization capacity, melting temperature and thermal stability were slightly affected by LA segment. The synergistic effects of LA segment and spinning process on PETLA structure and property were analyzed by WAXD and SAXS. The breaking strength of PETLA fibers dropped from 5.3 cN/dtex of PET to 2.8 cN/dtex of PET85LA15, which still met the requirements of most textile applications. Therefore, our work presented a feasible approach to prepare bio-based polyester fibers with tunable property.

Deposition of ZIF-67 and polypyrrole on current collector knitted from carbon nanotube-wrapped polymer yarns as a high-performance electrode for flexible supercapacitors.

Polymeric fiber fabrics with inherent mechanical flexibility, lightweight and porous textile structure are highly attractive as an ideal substrate for building flexible electrodes. However, their insulating nature limits their direct application as current collector. Here, we designed and fabricated a flexible conductive fabric from polymer yarns. This was achieved through wrapping polymer yarns with a carbon nanotube (CNT) cylinder, which was continuously prepared from a floating catalyst chemical vapor deposition process, and a subsequent knitting process. The derived CNT-wrapped polymer yarn fabric (CPYF) could directly serve as current collector/substrate to load zeolitic imidazolate framework-67 (ZIF-67) and polypyrrole (PPy) through in-situ growth and chemical polymerization. The resultant CPYF-ZIF-67-PPy displayed a maximum areal capacitance of 2308.8 mF cm-2 at 0.5 mA cm-2. Moreover, the assembled supercapacitor achieved a maximum areal energy density of 112 µW h cm-2 at the power density of 201.5 µW cm-2. Meanwhile, the device demonstrated an extraordinary flexibility with stable electrochemical properties after 5000 cycles of bending and 1000 cycles of stretching. This work therefore offers a new strategy that can be used to develop flexible conductive fabric for flexible supercapacitors.

Electromechanical Performance of Strain Sensors Based on Viscoelastic Conductive Composite Polymer Fibers.

Flexible conductive polymer composite (CPC) fibers that show large changes in resistance with deformation have recently gained much attention as strain-sensing components for future wearable electronics. However, the electrical resistance of these materials decays with time during dynamic cyclic loading, a deformation performed to simulate their real application as strain sensors. Despite the extensive research on CPC fibers, the mechanism leading to this decay in the electromechanical response under repetitive cycles remains unreported. Herein, this behavior is investigated using fiber-based strain sensors wet spun from thermoplastic polyurethane (TPU) consisting of a carbonaceous hybrid conductive filler system of carbon black (CB) and carbon nanotubes (CNTs). We found electrical viscosity to predict the observed electromechanical resistance decay. This implies that cycling these materials enables the relaxation of both the polymer chains and the conductive network. In addition, the resulting piezoresistive fibers are sensitive to deformation in the region of low strain (gauge factor of 6.0 within 3.0% strain), remain conductive under 280.5% deformation, and are stable for more than 2000 cycles. Finally, we demonstrate the potential of TPU/CB-CNT fibers as strain sensors for monitoring human motion.

Effect of pre-oxidation temperature and heating rate on the microstructure of lignin carbon fibers.

Lignin is a biopolymer with high carbon content, making lignin-based carbon fiber an important research direction. In the process of carbonization to prepare carbon fibers, lignin fibers are easily softened and fused, which destroys the microstructure of fibers, thereby reducing the quality of lignin-based carbon fibers. Therefore, it is non-negligible to pre-oxidize lignin fibers before carbonization to prevent fiber fusion and maintain fiber structure. Therefore, the effects of pre-oxidation temperature and heating rate on the structure of pre-oxidation lignin fibers with controllable diameter and thickness prepared by melt-blowing were studied in detail. During pre-oxidation, crosslinking and aromatization of lignin fibers occurred, and alkyl and benzene rings were mainly oxidized to form carbonyl groups. The aromatization degree of the pre-oxidized product was recorded at 280 °C and 0.25 °C/min, and the oxygen content reached 15 %-20 %, making it suitable for the preparation of bio-based carbon fibers. On this basis, carbon fibers with porous morphology can be prepared with a graphitization of 0.54 and a resistivity of 0.02 Ω cm-1. These materials are expected to be applicable in sensors, catalytic materials and other fields.

Activated Carbon Nanotube Fiber Fabric as a High-Performance Flexible Electrode for Solid-State Supercapacitors.

Owing to their features of excellent mechanical flexibility, high conductivity, and light weight, carbon-based fiber fabrics (CBFFs) are highly attractive as flexible electrodes for flexible solid-state supercapacitors (SCs). However, the achieved areal capacitance of most CBFFs is still unsatisfactory. Carbon nanotube fiber fabric (CNTFF) is a new kind of CBFF and could provide a potential alternative to high-performance flexible electrodes. Herein, we report the activation of CNTFF using a facile thermal oxidation and acid treatment process. The activated CNTFF shows an exceptional combination of large areal capacitance (1988 mF cm-2 at 2 mA cm-2), excellent rate performance (45% capacitance reservation at 100 mA cm-2), and outstanding cycle life (only 3% capacitance decay after 10,000 cycles). The constructed solid-state SC reaches a maximum energy density of 143 µWh cm-2 at 1000 µW cm-2 and a maximum power density of 30,600 µW cm-2 at 82 µWh cm-2. Additionally, this device possesses good rate performance along with superb cycle stability and excellent mechanical flexibility under various bending conditions. Our present work therefore offers a new opportunity in developing high-performance flexible electrodes for flexible energy storage.

Thermal Stability of Bio-Based Aliphatic-Semiaromatic Copolyester for Melt-Spun Fibers with Excellent Mechanical Properties.

Flexible aliphatic poly(lactic acid) is introduced into polyethylene terephthalate through copolymerization to prepare biodegradable copolyester, which aims to solve the non-degradability of polyethylene terephthalate (PET) and realize the greening of raw materials. In this work, poly(ethylene terephthalate-co-lactic acid) random copolyesters (PETLAs) of lactic acid composition from 10 to 50% is synthesized via one-pot method. The chemical structure and composition, thermal property, and crystallization property of prepared PETLAs resin are characterized. The results shows that the introduction of LA segment forms random copolyester, and the flexible LA segment results in slight decrease in the glass transition temperatures (Tg ), melting point (Tm ), and crystallinity (Xc ) of the copolyesters. The thermal stability of PETLAs is better, and the initial decomposition temperature of PETLA-10 can reach 394 °C. The PETLAs resin exhibits good processability, and PETLAs fibers are prepared by melt spinning. The strength of PETLA-10 fiber can reach 260 MPa after drawing treatment, and the elongation at break can reach 130%. Taking advantage of their features, PETLAs as an innovative bio-based polymer are expected to achieve ecofriendly applications in the fields of fiber, plastic, and film.

Progress and Perspective of Antiviral Protective Material.

Public health events caused by viruses pose a significant risk to humans worldwide. From December 2019 till now, the rampant novel 2019 coronavirus (SAR-CoV-2) has hugely impacted China and over world. Regarding a commendable means of protection, mask technology is relatively mature, though most of the masks cannot effectively resist the viral infections. The key material of the mask is a non-woven material, which makes the barrier of virus through filtration. Due to the lack of the ability to kill the viruses, masks are prone to cross-infection and become an additional source of infection after being discarded. If the filteration and antiviral effects can be simultaneously integrated into the mask, it will be more effcient, work for a longer time and create less difficulty in post-treatment. This mini-review presents the advances in antiviral materials, different  mechanisms of their activity, and their potential applications in personal protective fabrics. Furthermore, the article addresses the future challenges and directions of mask technology.

Integrating Nano-Cu2O@ZrP into In Situ Polymerized Polyethylene Terephthalate (PET) Fibers with Enhanced Mechanical Properties and Antibacterial Activities.

The approach of in situ polymerization modification has proven to be an effective route for introducing functions for polyester materials. In this work, Cu2O@ZrP nanosheets with excellent dispersity and high antibacterial activity were integrated into in situ polymerized polyethylene terephthalate (PET) fibers, revealing an enhanced mechanical performance in comparison with the PET fibers fabricated directly via a traditional melt blending method. Additionally, such an in situ polymerized PET/Cu2O@ZrP fibers displayed highly enhanced mechanical properties; and great antibacterial activities against multi-types of bacterium, including S. aureus, E. coli and C. albicans. For the as-obtained two types of PET/Cu2O@ZrP fibers, we have detailed their molecular weight (detailed molecular weight) and dispersibility of nano-Cu2O@ZrP and fibers crystallinity was investigated by Gel chromatography (GPC), Scanning electron microscope (SEM), and X-ray diffractometer (XRD), respectively. The results showed that the aggregation of the nano-Cu2O@ZrP in the resultant PET matrix could be effectively prevented during its in situ polymerization process, hence we attribute its highly enhanced mechanical properties to its superior dispersion of nano-Cu2O@ZrP.

Synthesis and characterization of size-controlled nano-Cu2O deposited on alpha-zirconium phosphate with excellent antibacterial property.

Ultra-small cuprous oxide (<10 nm) was deposited on the exterior face of alpha-zirconium phosphate (ɑ-ZrP). These nanoparticles have been successfully synthesized using ethylene diamine tetra acetic acid (EDTA) and ɑ-ZrP sheets as a chelating agent and template, respectively. In this article, nanosized cuprous oxide (Cu2O) loaded on the exterior face of ɑ-ZrP (Cu2O@ZrP) was prepared via a simple and convenient method. The coordination effect of EDTA stabilized the copper ions in solution and prevented agglomeration of Cu2O seed crystals into larger-sized particles. Moreover, the ɑ-ZrP sheets simultaneously acted as a template to further inhibit the growth of Cu2O grains. The Cu2O nanoparticles with the particle size of about 4 nm were uniformly loaded on the ZrP nanosheet. Furthermore, the antibacterial properties of Cu2O@ZrP hybrid materials and PET/Cu2O@ZrP antibacterial fabric were studied against E. coli (ATCC 25922) and S. aureus (ATCC 6538) by counting the number of surviving colonies. Ultra-small Cu2O of the Cu2O@ZrP composites lead to excellent antibacterial activity. It demonstrated that Cu2O@ZrP hybrid materials show great promise as antibacterial material widely used in various fields.