Controllable large-scale processing of temperature regulating sheath-core fibers with high-enthalpy for thermal management

Temperature regulating fibers(TRF_(s)) with high enthalpy and high form stability are the key factors for thermal management. However, the enthalpies of most TRFsare not high, and the preparation methods are still at the laboratory scale. It remains a great challenge to use industrial spinning equipment to achieve continuous processing of TRF_(s) with excellent thermal and mechanical properties. Here, polyamide 6(PA6) based TRF_(s) with a sheath-core structure were prepared by bicomponent melt-spinning. The sheath-core TRF(TRF_(sc)) are composed of PA6 as sheath and functional PA6 as core, which are filled with the shape stable phase change materials(ssPCM),dendritic silica@polyethylene glycol(SiO_(2)@PEG). With the aid of the sheath structure, the filling content of SiO_(2)@PEG can reach 30 %, so that the enthalpy of the TRF_(s) can be as high as 21.3 J/g. The ultra-high enthalpy guarantees the temperature regulation ability during the alternating process of cooling and heating. In hot environment, the temperature regulation time is 6.59 min, and the temperature difference is 12.93℃. In addition, the mechanical strength of the prepared TRF_(sc) reaches 2.26 cN/dtex, which can fully meet its application in the field of thermal management textiles and devices to manage the temperature regulation of the human body or precision equipment, etc.

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(Laserinduced graphene array).The biomimetic skin can realize self-adjusting in the range of 35–42℃,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 nextgeneration robotic and medical devices.

聚对苯二甲酸异山梨醇/乙二醇共聚酯及其熔纺纤维性能

通过三元共聚将生物基异山梨醇(Is)引入到聚对苯二甲酸乙二醇酯(PET)的分子链中,制备了系列聚对苯二甲酸异山梨醇/乙二醇共聚酯(PEIT)。进一步熔融纺丝获得了PEIT纤维。利用核磁共振波谱仪、凝胶渗透色谱、差示扫描量热仪、热重分析仪、X射线衍射仪及纤维强力仪分析研究了PEIT共聚酯的结构和性能。结果表明,Is刚性单元显著提高了PEIT的玻璃化转变温度(T g),保持了共聚物良好的热稳定性;同时破坏了分子链的规整性,使其结晶度有所降低。PEIT具有良好的可纺性,Is摩尔分数为5%时,PEIT纤维具有优异的力学性能,断裂强度较PET纤维增加了45%;仅当Is摩尔分数高于40%时,可拉伸性下降。

Lignin-based carbon fibers: Formation, modification and potential applications

As an aromatic polymer in nature, lignin has recently attracted gross attention because of its advantages of high carbon content, low cost and bio-renewability. However, most lignin is directly burnt for power generation to satisfy the energy demand of the pulp mills. As a result, only a handful of isolated lignin is used as a raw material. Thus, increasing value addition on lignin to expand its scope of applications is currently a challenge demanding immediate attention. Many efforts have been made in the valorization of lignin, including the preparation of precursors for carbon fibers. However, its complex structure and diversity significantly restrict the spinnability of lignin. In this review, we provide elaborate knowledge on the preparation of lignin-based carbon fibers ranging from the relationships among chemical structures, formation conditions and properties of fibers, to their potential applications. Specifically, control procedures for different spinning methods of lignin, including melt spinning, solution spinning and electrospinning, together with stabilization and carbonization are deeply discussed to provide an overall understanding towards the formation of lignin-based carbon fibers. We also offer perspectives on the challenges and new directions for future development of lignin-based carbon fibers.

One-step floating conversion of biomass into highly graphitized and continuous carbon nanotube yarns

The rapid growth of the demand for carbon nanotubes(CNTs) has greatly promoted their large-scale synthesis and development. However,the continuous production of CNT fibers by floating catalyst chemical vapor deposition(FCCVD) requires a large amount of non-renewable carbon sources. Here, the continuous production of highly graphitized CNT yarns from biomass tannic acid(TA) is reported. The chelation of TA and catalyst promotes the rapid cracking of biomass into carbon source gas, and the pyrolysis cracking produces the reducing gas, which solves the problems of the continuous production of CNT yarns using biomass. Through simple twisting, the mechanical strength of CNT yarn can reach 886 ± 46 MPa, and the electrical conductivity and graphitization(IG/ID) can reach 2 × 10^(5)S m^(-1)and 6.3, respectively. This work presents a promising solution for the continuous preparation of CNT yarns based on green raw material.

Intriguing anti-superbug Cu2O@ZrP hybrid nanosheet with enhanced antibacterial performance and weak cytotoxicity

In view of it's strong antibacterial function and minor toxicity,cuprous oxide (Cu2O) is frequently used in various broad-spectrum antibacterial reagents.Nonetheless the undesirable effects of superbugs still remain challenging.In this research,a chemical deposition approach is used to prepare a Cu2O@ZrP composite with nanosheet configuration demonstrating excellent dispersibility and antibacterial traits.From systematic analysis,it was inffered that the content of copper in the nanosheet was about 57-188 mg/g while the average thickness of the nanosheets Cu2O formed on ZrP is approximately 0.8 nm.The results of the minimal inhibitory concentration (MIC) revealed that an extremely low loading of Cu2O in Cu2O@ZrP nanosheet can lead to exceptional antibacterial activity.Examined on two various superbugs;i.e.methicillin-resistant staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE),the composite nanosheet reagent performed over 99% microbial reduction.More intesetingly,the cell growth rate of the Cu2O@ZrP nanosheet was determined to be 20% lower than that of the neat Cu2O,manifesting a weaker cytotoxicity.This unique hybrid nanosheet with intriguing anti-superbug performance promises highly efficient protection for the fabrics,battledress,and medical textiles.

High thermal stability Cu_(2)O@OZrP micro-nano hybrids for melt-spun excellent antibacterial activity polyester fibers

Public safety incidents caused by bacterial infections have attracted widespread attention towards antibacterial textiles(fibers,fabrics,etc.).Nevertheless,it is still challenging to efficiently load inorganic nano-antibacterial materials in polymer fibers.In this work,zirconium phosphate(ZrP,layered micro-nano materials)was utilized as a micro-nano carrier.The octadecyl triphenyl phosphonium bromide(OTP)was intercalated between the ZrP sheets by the ion exchange method to improve the carrier-polymer compatibility and the antibacterial performance.Through in-situ chemical reduction,the ultra-small nano-sized cuprous oxide(Cu_(2)O<5 nm)was loaded on the outer surface of ZrP to realize the uniform and stable dispersion of the Cu_(2)O on the carrier and improve the antibacterial performance.The ZrP nanosheets loaded with Cu_(2)O and OTP(Cu_(2)O@OZrP)had excellent antibacterial properties,and the antibacterial rate against E.coli,S.aureus and C.albicans was more than 99%.The intercalation amount of OTP in Cu_(2)O@OZrP can reach 16%,and the thermal stability was excellent and a significant increase in the Zeta potential.Indeed,the decomposition temperature was greater than 350℃,which was suitable for high-temperature melt processing of polymers.Consequently,we prepared PET/Cu_(2)O@OZrP fibers using polyethylene glycol terephthalate(PET),which accounts for 70%of the total chemical fibers,as the fiber matrix.PET/Cu_(2)O@OZrP fibers exhibited excellent mechanical property and antibacterial performance when the content of Cu_(2)O@OZrP was only 0.2%.The antibacterial rate against five types of bacteria including super bacteria(MRSA,VRE)was more than 99%.

1-D polymer ternary composites:Understanding materials interaction, percolation behaviors and mechanism toward ultra-high stretchable and super-sensitive strain sensors

A series of 1-D polymer ternary composites based on poly(styrene-butadiene-styrene)(SBS)/carbon nanotubes(CNTs)/few-layer graphene(FLG) conductive fibers(SCGFs)were prepared via wet-spinning. Employed as ultra-high stretchable and super-sensitive strain sensors, the ternary composite fiber materials’ interaction, percolation behaviors and mechanism were systematically explored. The resultant SCGFs-based strain sensors simultaneously exhibited high sensitivity, superior stretchability(with a gauge factor of 5,467 under 600% deformation) and excellent durability under different test conditions due to excellent flexibility of SBS, the synergistic effect of hybrid conductive nanofibers and the strong π-π interaction. Besides, the conductive networks in SBS matrix were greatly affected by the mass ratio of CNTs and FLG, and thus the piezoresistive performances of the strain sensors could be controlled by changing the content of hybrid conductive fillers. Especially, the SCGFs with 0.30 wt.%CNTs(equal to their percolation threshold 0.30 wt.%) and 2.7 wt.% FLG demonstrated the highest sensitivity owing to the bridge effect of FLG between adjacent CNTs. Whereas, the SCGFs with 1.0 wt.% CNTs(higher than their percolation threshold) and 2.0 wt.% FLG showed the maximum strain detection range(600%) due to the welding connection caused by FLG between the contiguous CNTs. To evaluate the fabricated sensors, the tensile and the cyclic mechanical recovery properties of SCGFs were tested and analyzed. Additionally, a theoretical piezoresistive mechanism of the ternary composite fiber was investigated by the evolution of conductive networks according to tunneling theory.

Effective and biocompatible antibacterial surfaces via facile synthesis and surface modification of peptide polymers

It is an urgent need to tackle drug-resistance microbial infections that are associated with implantable biomedical devices.Host defense peptide-mimicking polymers have been actively explored in recent years to fight against drug-resistant microbes.Our recent report on lithium hexamethyldisilazide-initiated superfast polymerization on amino acid N-carboxyanhydrides enables the quick synthesis of host defense peptide-mimicking peptide polymers.Here we reported a facile and cost-effective thermoplastic polyurethane(TPU)surface modification of peptide polymer(DLL:BLG=90:10)using plasma surface activation and substitution reaction between thiol and bromide groups.The peptide polymer-modified TPU surfaces exhibited board-spectrum antibacterial property as well as effective contact-killing ability in vitro.Furthermore,the peptide polymer-modified TPU surfaces showed excellent biocompatibility,displaying no hemolysis and cytotoxicity.In vivo study using methicillin-resistant Staphylococcus aureus(MRSA)for subcutaneous implantation infectious model showed that peptide polymer-modified TPU surfaces revealed obvious suppression of infection and great histocompatibility,compared to bare TPU surfaces.We further explored the antimicrobial mechanism of the peptide polymer-modified TPU surfaces,which revealed a surface contact-killing mechanism by disrupting the bacterial membrane.These results demonstrated great potential of the peptide-modified TPU surfaces for practical application to combat bacterial infections that are associated with implantable materials and devices.

Flexible Ceramic Fibers: Recent Development in Preparation and Application

Flexible ceramic fibers(FCFs)have been developed for various advanced applications due to their superior mechanical flexibility,high temperature resistance,and excellent chemical stability.In this article,we present an overview on the recent progress of FCFs in terms of materials,fabrication methods,and applications.We begin with a brief introduction to FCFs and the materials for preparation of FCFs.After that,various methods for preparation of FCFs are discussed,including centrifugal spinning,electrospinning,solution blow spinning,self-assembly,chemical vapor deposition,atomic layer deposition,and polymer conversion.Recent applications of FCFs in various fields are further illustrated in detail,including thermal insulation,air filtration,water treatment,sound absorption,electromagnetic wave absorption,battery separator,catalytic application,among others.Finally,some perspectives on the future directions and opportunities for the preparation and application of FCFs are highlighted.We envision that this review will provide readers with some meaningful guidance on the preparation of FCFs and inspire them to explore more potential applications.

Shape-stabilized phase change materials with high phase change enthalpy based on synthetic comb-like poly(acrylonitrile-co-ethylene glycol)for thermal management

Shape-stabilized poly（acrylonitrile-co-ethylene glycol） （PANEG） copolymer with comb-like structure was prepared via simple free-radical solution polymerization, where acrylic acid poly（ethylene glycol） methyl ether ester （MPEGA） and acrylonitrile （AN） were employed as monomers. Fourier transform infrared spectroscopy （FTIR）, 1H and 13C nuclear magnetic resonance spectroscopy （1H and 13C NMR）, wide-angle X-ray diffraction （WXAD） were used to characterize the chemical structure of resultant PANEG. In addition, the influences of MPEGA contents on energy storage performance, thermal reliability and thermal stability of PANEG materials were evaluated based on differential scanning calorimetry （DSC）, polarizing optical microscopy （POM）, thermal infrared imager and thermogravimetry analyzer （TG）. The comb-like PANEG demonstrated a favorable temperature regulation performance and thermal reliability. With the increase of MPEGA contents, the enthalpy of PANEG increased, and when the content of MPEGA was 80 wt%, the phase change enthalpy of synthesized PANEG-80 reached to 106.70 J/g with a stable heat storage performance after 100 thermal cycling. Thermal infrared images and cooling curves revealed that synthetic PANEG could sustain a temperature in ranges of 22-31 ℃ for continuous 25 min, presenting excellent temperature regulation performance. Also, comb-like PANEG could be uniformly dissolved in dimethyl sulfoxide （DMSO）, indicating that PANEG phase change fibers with potential applications in fields of intelligent thermoregulating textile and heat energy management could be obtained via one-step wet spinning.

Advances in Nonwoven‑Based Separators for Lithium‑Ion Batteries

Lithium-ion batteries(LIBs)are energy-storage devices with a high-energy density in which the separator provides a physical barrier between the cathode and anode,to prevent electrical short circuits.To meet the demands of high-performance batteries,the separator must have excellent electrolyte wettability,thermotolerance,mechanical strength,highly porous structures,and ionic conductivity.Numerous nonwoven-based separators have been used in LIBs due to their high porosity and large surface-to-volume ratios.However,the fabrication of multi-functional fibers,the construction of nonwoven separators,and their integration into energy-storage devices present grand challenges in fundamental theory and practical implementation.Herein,we systematically review the up-to-date concerning the design and preparation of nonwoven-based separators for LIBs.Recent progress in monolayer,composite,and solid electrolyte nonwoven-based separators and their fabrication strategies is discussed.Future challenges and directions toward advancements in separator technologies are also discussed to obtain separators with remarkable performance for high-energy density batteries.

Ultra-fast bacterial inactivation of Cu_(2)O@halloysite nanotubes hybrids with charge adsorption and physical piercing ability for medical protective fabrics

Metals have been used for wound treatment and toxicity testing since ancient times.With the development of nanotechnology,metal oxides have been proven to have excellent sterilization and disinfection functions.However,the rapid bacterial inactivation efficiency and trapping physicochemical killing ability remain simultaneously undemonstrated in antibacterial nanohybrids.Here,we demonstrate a method for in-situ reduction of small-sized Cu_(2)O particles on one-dimensional inorganic halloysite nanotubes(HNTs).The resultant Cu_(2)O@HNTs hybrids not only give Cu_(2)O excellent dispersibility,but also exert the synergistic effect of the charge adsorption of metal oxides and the physical piercing effect of the small-sized nanotubes.Furthermore,the release of Cu^(2+)from hybrids damages cell membranes and denatures proteins and DNA.Through this sterilization mechanism,Cu_(2)O@HNTs allow for the inactivation rate of Escherichia coli to reach 94.5%within 2 min and complete inactivation within 10 min.This excellent sterilization mode makes Cu_(2)O@HNTs exhibit excellent broad-spectrum antibacterial activity and inactivation efficiency,while shows weak cytotoxicity.These hybrids were further applied in the processing of functional antibacterial fibers and fabrics.Thus,we believe that this excellent antibacterial hybrid is practically attractive in this critical time of the COVID-19 pandemic.

Efficient and Homogenous Precipitation of Sulfur Within a 3D Electrospun Heterocatalytic Rutile/Anatase TiO2‑x Framework in Lithium–Sulfur Batteries

Lithium–sulfur(Li–S)batteries can potentially outperform state-of-the-art lithium-ion batteries,but their further development is hindered by challenges,such as poor electrical conductivity of sulfur and lithium sulfide,shuttle phenomena of lithium polysulfides,and uneven distribution of solid reaction products.Herein,free-standing carbon nanofibers embedded with oxygen-deficient titanium dioxide nanoparticles(TiO_(2-x)/CNFs)has been fabricated by a facile electrospinning method,which can support active electrode materials without the need for conductive carbon and binders.By carefully controlling the calcination temperature,a mixed phase of rutile and anatase was achieved in the TiO_(2-x)nanoparticles.The hybridization of anatase/rutile TiO_(2-x)and the oxygen vacancy in TiO_(2-x)play a crucial role in enhancing the conversion kinetics of lithium polysulfides(LiPSs),mitigating the shuttle effect of LiPSs,and enhancing the overall efficiency of the Li–S battery system.Additionally,the free-standing TiO_(2-x)/CNFs facilitate uniform deposition of reaction products during cycling,as confirmed by synchrotron X-ray imaging.As a result of these advantageous features,the TiO_(2-x)/CNFs-based cathode demonstrates an initial specific discharge capacity of 787.4 mAh g^(−1)at 0.5 C in the Li–S coin cells,and a final specific discharge capacity of 584.0 mAh g^(−1) after 300 cycles.Furthermore,soft-packaged Li–S pouch cells were constructed using the TiO_(2-x)/CNFs-based cathode,exhibiting excellent mechanical properties at different bending states.This study presents an innovative approach to developing free-standing sulfur host materials that are well suited for flexible Li–S batteries as well as for various other energy applications.