In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in har...In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.展开更多
Layered assembled membranes of 2D leaf-like zeolitic imidazolate frameworks(ZIF-L)nanosheets have received great attention in the field of water treatment due to the porous structure and excellent antibacterial abilit...Layered assembled membranes of 2D leaf-like zeolitic imidazolate frameworks(ZIF-L)nanosheets have received great attention in the field of water treatment due to the porous structure and excellent antibacterial ability,but the dense accumulation on the membrane surface and the low permeate flux greatly hinder their application.Herein,we synthesized m HNTs(modified halloysite nanotubes)/ZIF-L nanocomposites on modified m HNTs by in situ growth method.Interestingly,due to the different size of m HNTs and ZIF-L,m HNTs were packed in ZIF-L nanosheets.The hollow m HNTs provided additional transport channels for water molecules,and the accumulation of the ZIF-L nanosheets was decreased after assembling m HNTs/ZIF-L nanocomposites into membrane by filtration.The prepared m HNTs/ZIF-L membrane presented high permeate flux(59.6 L·m^(-2)·h^(-1)),which is 2-4 times of the ZIF-L membranes(14.8 L·m^(-2)·h^(-1)).Moreover,m HNTs/ZIF-L membranes are intrinsically antimicrobial,which exhibit extremely high bacterial resistance.We provide a controllable strategy to improve 2D ZIF-L assembles,and develops novel membranes using 2D package structure as building units.展开更多
The N-doped TiO2-loaded halloysite nanotubes(N-Ti O2/HNTs) nanocomposites were prepared by using chemical vapor deposition method which was realized in autoclave. The photocatalytic activity of nanocomposites was eval...The N-doped TiO2-loaded halloysite nanotubes(N-Ti O2/HNTs) nanocomposites were prepared by using chemical vapor deposition method which was realized in autoclave. The photocatalytic activity of nanocomposites was evaluated by virtue of the decomposition of formaldehyde gas under solar-light irradiation. The XRD patterns verified that the anatase structured TiO2 was deposited on HNTs. The TEM images showed that the surface of HNTs was covered with nanosized TiO2 with a particle size of ca. 20 nm. The UV-vis spectra indicated that the N-Ti O2/HNTs presented a significant absorption band in the visible region between 400 nm and 600 nm. Under solar-light irradiation, the highest degradation rate of formaldehyde gas attained 90% after 100 min of solar-light irradiation. The combination of the photocatalytic property of TiO2 and the unique structure of halloysite would assert a promising perspective in degradation of organic pollutants.展开更多
In this work,Fe_(3)O_(4) nanoparticles(NPs)loaded inside and outside halloysite nanotubes(HNTs)were prepared and developed as the heterogeneous Fenton-like catalysts for the removal of representative organic pollutant...In this work,Fe_(3)O_(4) nanoparticles(NPs)loaded inside and outside halloysite nanotubes(HNTs)were prepared and developed as the heterogeneous Fenton-like catalysts for the removal of representative organic pollutants.Characterization results indicated that the samples with Fe_(3)O_(4) NPs loaded outside the HNTs lumen(Fe_(3)O_(4)/HNTs)and inside the HNTs lumen(Fe_(3)O_(4)@HNTs)were successfully prepared.Both samples had typical magnetic hysteresis loops,while Fe_(3)O_(4)@HNTs exhibited higher magnetization intensity.The comparative experiments showed that Fe_(3)O_(4)@HNTs had better Fenton-like catalytic ability than that of Fe_(3)O_(4)/HNTs in the degradation of various organic pollutants.Taking Rhodamine B(RhB)as an example,the adsorption thermodynamics and kinetics of RhB onto Fe_(3)O_(4)/HNTs and Fe_(3)O_(4)@HNTs were also investigated.The comparative results demonstrated that the adsorption ability of Fe_(3)O_(4)/HNTs was better than that of Fe_(3)O_(4)@HNTs.Moreover,the dissolved concentration of Fe^(2+)and production amount of hydroxyl radical(·OH)in the Fe_(3)O_(4)@HNTs-H_(2)O_(2) system were significantly higher than those in the Fe_(3)O_(4)/HNTs-H_(2)O_(2) system.Based on aforementioned comparison,the nano-confinement effect in the Fe_(3)O_(4)@HNTs-H_(2)O_(2) system was verified.This work provides meaningful guidance for the cheap and convenient design of nanoreactors for Fenton-like applications.展开更多
It is challenging for antibacterial polymer scaffolds to achieve the drug sustained-release through directly coating or blending.In this work,halloysite nanotubes(HNTs),a natural aluminosilicate nanotube,were utilized...It is challenging for antibacterial polymer scaffolds to achieve the drug sustained-release through directly coating or blending.In this work,halloysite nanotubes(HNTs),a natural aluminosilicate nanotube,were utilized as a nano container to load nano silver(Ag)into the lumen through vacuum negativepressure suction&injection and thermal decomposition of silver acetate.Then,the nano Ag loaded HNTs(HNTs@Ag)were introduced to poly-l-lactic acidide)(PLLA)scaffolds prepared by additive manufacturing for the sustained-release of Ag^+.Acting like a’shield’,the tube walls of HNTs not only retarded the erosion of external aqueous solution on internal nano Ag to generate Ag^+but also postponed the generated Ag^+to diffuse outward.The results indicated the PLLA-HNTs@Ag nanocomposite scaffolds achieved a sustained-release of Ag^+over 28 days without obvious initial burst release.Moreover,the scaffolds exhibited a long-lasting antibacterial property without compromising the cytocompatibility.Besides,the degradation properties,biomineralization ability and mechanical properties of the scaffolds were increased.This study suggests the potential application of inorganic nanotubes as drug carrier for the sustained-release of functional polymer nanocomposite scaffolds.展开更多
All-solid-state lithium batteries(ASSLB) are promising candidates for next-generation energy storage devices.Nevertheless,the large-scale commercial application of high energy density AS S LB with the polymer electrol...All-solid-state lithium batteries(ASSLB) are promising candidates for next-generation energy storage devices.Nevertheless,the large-scale commercial application of high energy density AS S LB with the polymer electrolyte still faces challenges.In this study,a thin solid polymer composite electrolyte(SPCE) is prepared through a facile and cost-effective strategy with an infiltration of thermoplastic polyurethane(TPU),lithium salt(LiTFSI or LiFSI),and halloysite nanotubes(HNTs) in a porous framework of polyethylene separator(PE)(TPU-HNTs-LiTFSI-PE or TPU-HNTs-LiFSI-PE).The composition,electrochemical performance,and especially the effect of anions(TFSI-and FSI-) on cycling performance are investigated.The results reveal that the flexible TPU-HNTs-LiTFSI-PE and TPU-HNTs-LiFSI-PE with a thickness of 34 μm exhibit wide electrochemical windows of 4.9 and 5.1 V(vs.Li+/Li) at 60℃,respectively.Reduction in FSI-tends to form more LiF and sulfur compounds at the interface between TPU-HNTs-LiFSI-PE and Li metal anode,thus enhancing the interfacial stability.As a result,cell composed of TPU-HNTs-LiFSI-PE exhibits a smaller increase in interfacial resistance of solid electrolyte interphase(SEI) with a distinct decrease in charge-transfer resistance during cycling.Li|Li symmetric cell with TPU-HNTs-LiFSI-PE could keep its stable overpotential profile for nearly 1300 h with a low hysteresis of approximately39 mV at a current density of 0.1 mA cm-2,while a sudden voltage rise with internal cell impedance-surge signals was observed within 600 h for cell composed of TPU-HNTs-LiTFSI-PE.The initial capacities of NCMITPU-HNTs-LiTFSIPEILi and NCMITPU-HNTs-LiFSI-PEILi cells were 149 and 114 mAh g-1,with capacity retention rates of 83.52% and89.99% after 300 cycles at 0.5 C,respectively.This study provides a valuable guideline for designing flexible SPCE,which shows great application prospect in the practice of ASSLB.展开更多
Various enzymatic reactions or enzymatic cascade reactions occur efficiently in biological microsystems due to space constraints or orderly transfer of intermediate products. Inspired by this, the horseradish peroxida...Various enzymatic reactions or enzymatic cascade reactions occur efficiently in biological microsystems due to space constraints or orderly transfer of intermediate products. Inspired by this, the horseradish peroxidase(HRP)-like nanozyme(Fe-aminoclay) was in situ synthesized on the surface of alkali-activated halloysite nanotubes and the natural enzyme(glucose oxidase, GOx) was immobilized on it to construct a high-efficiency GOx-Fe AC@AHNTs cascade nanoreactor. In which, Fe AC@AHNTs can not only be used as a carrier for immobilized enzymes, but also help its catalytic activity to cooperate with glucose oxidase in a cascade reaction. The microcompartments and substrate channel effect of this enzyme-nanozyme microsystem exhibit a superior catalytic performance than that of natural enzyme system, and exhibits excellent long-term stability and recyclability. Subsequently, the GOx-Fe AC@AHNTs cascade nanoreactor was employed as a glucose colorimetric platform, which displayed a low detection limit(0.47 μmol/L)in glucose detection. This enzyme-nanoenzyme nanoreactor provides a simple and effective example for constructing a multi-enzyme system with limited space, and lays the foundation for subsequent research in the fields of biological analysis and catalysis.展开更多
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.Howeve...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.展开更多
Targeted drug delivery systems have attracted a great deal of interest by virtue of their potential use in chemotherapy. In this study, multicomponent halloysite nanotubes （HNTs） have been evaluated as a platform to...Targeted drug delivery systems have attracted a great deal of interest by virtue of their potential use in chemotherapy. In this study, multicomponent halloysite nanotubes （HNTs） have been evaluated as a platform to assist and direct the delivery of anticancer drug doxorubicin （DOX） into cancer cells. Folic acid （FA） and magnetite nanopar- ticles were successfully grafted onto HNTs via amide reaction whereas the drug has been introduced by capitalizing electrostatic interaction between cationic drug and anionic exterior of HNTs, which eventually leads to pH respon- sive release. The resultant DOX loaded FA-Fe304@HNTs were well characterized by transmission electron mi- croscopy （TEM）, scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FTIR） and XRD. The clinical efficacy of the system was validated by confocal microscopy and cell cytotoxicity assay （MTT assay）. MTT assay results revealed a high biocompatibility up to a concentration of 200 μg/mL of HNTs, while, DOX loaded FA-Fe304@HNTs were markedly cytotoxic to HeLa cells. This multifunctional nanovehicle has a great po- tential for cancer diagnosis and therapy, and could further advance the clinical use of nanomedicine.展开更多
Halloysite nanotubes(HNTs)have been considered as a promising flame retardant fillers for polymers.In this work,the polyhedral oligomericsilsesquioxane(POSS)containing amino group was covalently grafted on the surface...Halloysite nanotubes(HNTs)have been considered as a promising flame retardant fillers for polymers.In this work,the polyhedral oligomericsilsesquioxane(POSS)containing amino group was covalently grafted on the surface of HNTs with 3-(2,3-epoxypropoxy)propytrimethoxysilane as a chemical bridge.The POSS modified HNTs(HNTs-POSS)dispersed uniformly in the thermoplastic polyurethane(TPU)matrix and endowed TPU nanocomposites with enhanced tensile properties and fire safety.Cone calorimeter tests revealed that the introduction of 2 wt%HNTs-POSS to TPU matrix remarkably reduced the peak of heat release rate(PHRR)and total heat release(THR)by 60.0%and 18.3%,respectively.In addition,the peak CO production rate and total smoke release(TSR)could be significantly suppressed by the addition of HNTsPOSS.The well dispersed HNTs in combination with the ceramified silicon network from the thermal decomposition of POSS contributed to the formation of a continuous and compact char layer,exhibiting a tortuous effect by inhibiting heat diffusion and evaporation of volatile gaseous.In addition,the released crystal water from HNTs could dilute the combustible volatiles and then decline the combustion intensity.The tensile tests demonstrated that introduction of 2 wt%HNTs-POSS would enhance the maximum stress of TPU nanocomposite with a slight decrease of elongation at break.The combination of HNTs and POSS through the construction of effective interfacial interactions provides a feasible way to effectively enhance the fire safety of TPU nanocomposites without scarifying ductility.展开更多
Introducing inorganic nanomaterials into a polymer matrix greatly improves the anticorrosion performance of epoxy coatings(EP);however,poor compatibility between the materials can limit the improvement in properties.I...Introducing inorganic nanomaterials into a polymer matrix greatly improves the anticorrosion performance of epoxy coatings(EP);however,poor compatibility between the materials can limit the improvement in properties.In this work,based on the high interface compatibility of two-dimensional(2D)Co_(2)(OH)_(2)BDC(BDC=1,4-benzenedicarboxylate)in the epoxy coating that we reported in previous work,we fabricated a 2D Co_(2)(OH)_(2)BDC-halloysite nanotube(HNT)nanocomposite have a structure consisting of alternating of nanosheets and nanotube by in situ synthesis.The nanocomposite was characterized by Fourier transform infrared spectroscopy,X-ray diffraction,and scanning electron microscopy.The mechanical and anticorrosion performance of the 2D Co_(2)(OH)_(2)BDC-HNT/EP coating was evaluated by mechanical tests and electrochemical impedance spectroscopy spectra.Compared with a conventional unreinforced epoxy coating,the 2D Co_(2)(OH)_(2)BDC-HNT/EP coating had higher mechanical strength and toughness,and the low-frequency impedance modulus of 2D Co_(2)(OH)_(2)BDC-HNT/EP coating was increased by three orders of magnitude,demonstrating the high corrosion resistance of our reinforced coating.展开更多
Halloysite nanotubes were used as nanocontainers to hold corrosion inhibitors such as Ce^(3+)-Zr^(4+),2-mercaptobenzothiazole and 8-hydroxyquinoline in their lumen.An acid assisted etching of the nanotubes was carried...Halloysite nanotubes were used as nanocontainers to hold corrosion inhibitors such as Ce^(3+)-Zr^(4+),2-mercaptobenzothiazole and 8-hydroxyquinoline in their lumen.An acid assisted etching of the nanotubes was carried out with a view to increase the lumen diameter and thereby,increase the amount of loading of the corrosion inhibitor.The morphology of as-received and etched halloysite nanotubes was ob-served using TEM analysis.The loading of corrosion inhibitors was confirmed using SEM-EDS and BET analysis.Polymeric microcapsules were used as capping agents for the ends of the loaded HNTs following which,they were dispersed into a hybrid sol-gel silica matrix.Dip coating method was used to generate coatings on AZ91D substrates followed by heat treatment at 130℃ for 1 h.The release rate kinetics of corrosion inhibitors from as-received and etched nanotubes was investigated in buffer solutions of 3.5 wt%NaCl at different pH.The release mechanism of corrosion inhibitors from the HNT lumen was validated using various semi-empirical models.Coatings were also evaluated for their corrosion protection ability using electrochemical techniques after exposure to 3.5 wt%NaCl solution for 120 h.Coatings generated using Ce^(3+)-Zr^(4+)loaded into as-received halloysite nanotubes have shown more effective corrosion protection when compared to other corrosion inhibitors after 120 h exposure to the corrosive medium.展开更多
A natural nanotubular material,halloysite nanotubes(HNTs),was introduced to prepare styrene-butadiene rubber/modified halloysite nanotube(SBR/m-HNT) nanocomposites.Complex of resorcinol and hexamethylenetetramine (RH)...A natural nanotubular material,halloysite nanotubes(HNTs),was introduced to prepare styrene-butadiene rubber/modified halloysite nanotube(SBR/m-HNT) nanocomposites.Complex of resorcinol and hexamethylenetetramine (RH) was used as the interfacial modifier.The structure,morphology and mechanical properties of SBR/m-HNT nanocomposites,especially the interfacial interactions,were investigated.SEM and TEM observations showed that RH can not only facilitate the dispersion and orientation of HNTs in SBR matrix at ...展开更多
Novel cobalt Fischer-Tropsch synthesis （FTS） catalysts were prepared from natural halloysite nanotubes （HNT） by double-solvent and wet- impregnation methods, and characterized by TEM, XRD, TPR and N2 adsorption-de...Novel cobalt Fischer-Tropsch synthesis （FTS） catalysts were prepared from natural halloysite nanotubes （HNT） by double-solvent and wet- impregnation methods, and characterized by TEM, XRD, TPR and N2 adsorption-desorption. Comparing with the catalyst prepared by wet- impregnation method, the catalyst prepared by double-solvent method reduces Co3O4 particle migration and agglomeration due to size-induced effect, thus showing higher catalytic activity for Fischer-Tropsch synthesis.展开更多
Halloysite nanotube-composited thermo-responsive hydrogel system has been successfully developed for controlled drug release by copolymerization of N-isopropylacrylamide （NIPAM） with silane-modified halloysite nanot...Halloysite nanotube-composited thermo-responsive hydrogel system has been successfully developed for controlled drug release by copolymerization of N-isopropylacrylamide （NIPAM） with silane-modified halloysite nanotubes （HNT） through thermally initiated free-radical polymerization. With methylene blue as a model drug, thermo-responsive drug release results demonstrate that the drug release from the nanotubes in the composited hy-drogel can^be well controlled by manipulating the environmental temperature. When the hydrogel network is swol- len at temperature below the lower critical solution temperature （LCST）, drug releases steadily from lumens of the embedded nanotubes, whereas the drug release stops when hydrogel shrinks at temperature above the LCST. The release of model drug from the HNT-composited hydrogel matches well with its thermo-responsive volume phasetransition, and shows characteristics of well controlled release. The design strategy and release results of the pro- posed novel HNT-composited thermo-responsive hydrogel system provide valuable guidance for designing respon- s_i_ve nanocomposites for controlled-release of active agents.展开更多
This work reports a comprehensive study on poly(Ethylmethacrylateco-Acrylonitrile)Poly(EMA-AN)nanocomposites reinforced with a hybrid mixture of nanoreiforcements based on nanocrystals of cellulose(NCC)(1 or 5%wt)and ...This work reports a comprehensive study on poly(Ethylmethacrylateco-Acrylonitrile)Poly(EMA-AN)nanocomposites reinforced with a hybrid mixture of nanoreiforcements based on nanocrystals of cellulose(NCC)(1 or 5%wt)and halloysite nanotubes(HNTs)(1 or 5%wt).The morphology,thermal and mechanical properties of these nanocomposites were characterized.Homogeneous dispersion of the nanofillers has been shown by scanning electron microscopy.A significant increase of the rubbery modulus and glass transition temperature were obtained upon filler addition,due to the reduction of mobility of the matrix macromolecular chains.On the other hand,compared with the neat Poly(EMAAN),the storage modulus of the nanocomposites increased by a factor 38 when adding 5 wt%NCC and by 17 for the same concentration of HNTs.mechanical properties of ternary nanocomposites were furthers increased resulting from a synergistic effect of these two nanofillers.展开更多
This study presents the modification of surfaces of nanoclays, halloysite nanotubes (HNT) and sepiolite (SEP), with styrene-maleic anhydride copolymers (SMA) via esterification reaction between hydroxyl groups of the ...This study presents the modification of surfaces of nanoclays, halloysite nanotubes (HNT) and sepiolite (SEP), with styrene-maleic anhydride copolymers (SMA) via esterification reaction between hydroxyl groups of the nanoclays and anhydride groups of SMA. The structural, thermal, and morphological analyses of the modified nanoclays were performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermal gravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). All of these results suggested that the expected modification of HNT and SEP surfaces were performed. Although XRD patterns of HNT containing samples showed that the basal spacing shifted to higher distances, it was found that those of the crystalline structure of SEP remained unchanged. Thermal gravimetric analysis exhibited that SMA copolymers were grafted onto the surfaces of nanoclays varying amounts between 15 and 43 wt. % depending on the types of nanoclays and SMA copolymers. This modification indicates that these nanoclays can be added to the polystyrene matrix without any compatibilizers.展开更多
In this study, the effects of halloysite nanotubes （HNTs） reinforcement in expandable graphite based intumescent fire retardant coatings （IFRCs） developed using a polydimethylsiloxane （PDMS）/phenol BA epoxy syst...In this study, the effects of halloysite nanotubes （HNTs） reinforcement in expandable graphite based intumescent fire retardant coatings （IFRCs） developed using a polydimethylsiloxane （PDMS）/phenol BA epoxy system were investigated. Intumescent coating formulations were developed by incorporating different weight percentages of HNTs and PDMS in basic intumescent ingredients （ammonium polyphosphate/melamine/boric acid/expandable graphite, APP/MEL/BA/EG）. The performance of intumescent formulations was investigated by furnace fire test, Bunsen burner fire test, field emission electron microscopy （FESEM）, thermogravimetric analysis （TGA）, transmission electron microscopy （TEM）, and Fourier transform infrared analysis （FTIR）. The Bunsen burner fire test results indicated that the fire performance of HNTs and PDMS reinforced intumescent formulation has improved due to the development of silicate network over the char residue. Improved expansion in char residue was also noticed in the formulation, SH（3）, due to the minimum decomposition of char carbon. FESEM and TEM results validated the development of silicate network over char layer of coating formulations. A considerable mass loss difference was noticed during thermal gravimetric analysis （TGA） of intumescent coating formulations. Reference formulation, SH（0） with no filler, degraded at 300 ~C and lost 50% of its total mass but SH（3）, due to synergistic effects between PDMS and HNTs, degraded above 400 ~C and showed the maximum thermal stability. XRD analysis showed the development of thermally stable compound mulltie, due to the synergism of HNTs and siloxane during intumescent reactions, which enhanced fire performance. FTIR analysis showed the presence of incorporated siloxane and silicates bonds in char residue, which endorsed the toughness of intumescent char layer produced. Moreover, the synergistic effect ofHNTs, PDMS, and other basic intumescent ingredients enhanced the polymer cross-linking in binder system and improved fire resistive performance of coatings.展开更多
Coating inorganic ceramic particles on commercial polyolefin separators has been considered as an effective strategy to improve thermostability of separator.However,the introduction of the coating layer could induce p...Coating inorganic ceramic particles on commercial polyolefin separators has been considered as an effective strategy to improve thermostability of separator.However,the introduction of the coating layer could induce pore blockage on the surface of the polyolefin separator.Herein,a ceramic composite layer that consists of alumina nanoparticles(n-Al_(2)O_(3))and halloysite nanotubes(HNTs)is designed to modify the polyethylene(PE)separator(the modified separator is denoted as AH-PE).The HNTs with hollow nanotubular structure construct a light skeleton and provide fast ion transport channels while Al_(2)O_(3)particles function as heat-resistant fillers to inhibit the shrinkage of the separator at elevated temperatures.The total thickness of AH-PE separator is only 14μm.Consequently,the mass increment of AH-PE separator decreases from 5 g/m^(2)to 3.5 g/m^(2),and the Gurley value reduces by 23%,compared with Al_(2)O_(3)coated PE separator(A-PE).Due to the synergistic effects of Al_(2)O_(3)and HNTs,AH-PE separator exhibits highly improved thermal stability(almost no shrinkage at 170℃for 30 min),high Li^(+)transference number(up to 0.47),and long cycle life of 450 h for Li|Li cells.Moreover,the Li Fe PO_(4)/Li cells assembled with AH-PE separators demonstrate improved rate capability and safety performance.展开更多
Tendon and ligament injuries are the most common musculoskeletal injuries,which not only impact the quality of life but result in a massive economic burden.Surgical interventions for tendon/ligament injuries utilize b...Tendon and ligament injuries are the most common musculoskeletal injuries,which not only impact the quality of life but result in a massive economic burden.Surgical interventions for tendon/ligament injuries utilize biological and/or engineered grafts to reconstruct damaged tissue,but these have limitations.Engineered matrices confer superior physicochemical properties over biological grafts but lack desirable bioactivity to promote tissue healing.While incorporating drugs can enhance bioactivity,large matrix surface areas and hydrophobicity can lead to uncontrolled burst release and/or incomplete release due to binding.To overcome these limitations,we evaluated the delivery of a peptide growth factor(exendin-4;Ex-4)using an enhanced nanofiber matrix in a tendon injury model.To overcome drug surface binding due to matrix hydrophobicity of poly(caprolactone)(PCL)-which would be expected to enhance cell-material interactions-we blended PCL and cellulose acetate(CA)and electrospun nanofiber matrices with fiber diameters ranging from 600 to 1000 nm.To avoid burst release and protect the drug,we encapsulated Ex-4 in the open lumen of halloysite nanotubes(HNTs),sealed the HNT tube endings with a polymer blend,and mixed Ex-4-loaded HNTs into the polymer mixture before electrospinning.This reduced burst release from~75%to~40%,but did not alter matrix morphology,fiber diameter,or tensile properties.We evaluated the bioactivity of the Ex-4 nanofiber formulation by culturing human mesenchymal stem cells(hMSCs)on matrix surfaces for 21 days and measuring tenogenic differentiation,compared with nanofiber matrices in basal media alone.Strikingly,we observed that Ex-4 nanofiber matrices accelerated the hMSC proliferation rate and elevated levels of sulfated glycosaminoglycan,tendon-related genes(Scx,Mkx,and Tnmd),and ECM-related genes(Col-Ⅰ,Col-Ⅲ,and Dcn),compared to control.We then assessed the safety and efficacy of Ex-4 nanofiber matrices in a full-thickness rat Achilles tendon defect with histology,marker expression,functional walking track analysis,and mechanical testing.Our analysis confirmed that Ex-4 nanofiber matrices enhanced tendon healing and reduced fibrocartilage formation versus nanofiber matrices alone.These findings implicate Ex-4 as a potentially valuable tool for tendon tissue engineering.展开更多
文摘In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.
基金supported by the Excellent Youth Foundation of Henan Scientific Committee,China(222300420018)Key Scientific Research Projects in Universities of Henan Province,China(21zx006)。
文摘Layered assembled membranes of 2D leaf-like zeolitic imidazolate frameworks(ZIF-L)nanosheets have received great attention in the field of water treatment due to the porous structure and excellent antibacterial ability,but the dense accumulation on the membrane surface and the low permeate flux greatly hinder their application.Herein,we synthesized m HNTs(modified halloysite nanotubes)/ZIF-L nanocomposites on modified m HNTs by in situ growth method.Interestingly,due to the different size of m HNTs and ZIF-L,m HNTs were packed in ZIF-L nanosheets.The hollow m HNTs provided additional transport channels for water molecules,and the accumulation of the ZIF-L nanosheets was decreased after assembling m HNTs/ZIF-L nanocomposites into membrane by filtration.The prepared m HNTs/ZIF-L membrane presented high permeate flux(59.6 L·m^(-2)·h^(-1)),which is 2-4 times of the ZIF-L membranes(14.8 L·m^(-2)·h^(-1)).Moreover,m HNTs/ZIF-L membranes are intrinsically antimicrobial,which exhibit extremely high bacterial resistance.We provide a controllable strategy to improve 2D ZIF-L assembles,and develops novel membranes using 2D package structure as building units.
基金supported by the Talent Introduction Fund of Yangzhou Universitythe Jiangsu Social Development Project(BE2014613)the Six Talent Peaks of Jiangsu province(2014-XCL-013)
文摘The N-doped TiO2-loaded halloysite nanotubes(N-Ti O2/HNTs) nanocomposites were prepared by using chemical vapor deposition method which was realized in autoclave. The photocatalytic activity of nanocomposites was evaluated by virtue of the decomposition of formaldehyde gas under solar-light irradiation. The XRD patterns verified that the anatase structured TiO2 was deposited on HNTs. The TEM images showed that the surface of HNTs was covered with nanosized TiO2 with a particle size of ca. 20 nm. The UV-vis spectra indicated that the N-Ti O2/HNTs presented a significant absorption band in the visible region between 400 nm and 600 nm. Under solar-light irradiation, the highest degradation rate of formaldehyde gas attained 90% after 100 min of solar-light irradiation. The combination of the photocatalytic property of TiO2 and the unique structure of halloysite would assert a promising perspective in degradation of organic pollutants.
基金supported by the Natural Science Foundation of Heilongjiang Province,China(Grant No.LH2022E083).
文摘In this work,Fe_(3)O_(4) nanoparticles(NPs)loaded inside and outside halloysite nanotubes(HNTs)were prepared and developed as the heterogeneous Fenton-like catalysts for the removal of representative organic pollutants.Characterization results indicated that the samples with Fe_(3)O_(4) NPs loaded outside the HNTs lumen(Fe_(3)O_(4)/HNTs)and inside the HNTs lumen(Fe_(3)O_(4)@HNTs)were successfully prepared.Both samples had typical magnetic hysteresis loops,while Fe_(3)O_(4)@HNTs exhibited higher magnetization intensity.The comparative experiments showed that Fe_(3)O_(4)@HNTs had better Fenton-like catalytic ability than that of Fe_(3)O_(4)/HNTs in the degradation of various organic pollutants.Taking Rhodamine B(RhB)as an example,the adsorption thermodynamics and kinetics of RhB onto Fe_(3)O_(4)/HNTs and Fe_(3)O_(4)@HNTs were also investigated.The comparative results demonstrated that the adsorption ability of Fe_(3)O_(4)/HNTs was better than that of Fe_(3)O_(4)@HNTs.Moreover,the dissolved concentration of Fe^(2+)and production amount of hydroxyl radical(·OH)in the Fe_(3)O_(4)@HNTs-H_(2)O_(2) system were significantly higher than those in the Fe_(3)O_(4)/HNTs-H_(2)O_(2) system.Based on aforementioned comparison,the nano-confinement effect in the Fe_(3)O_(4)@HNTs-H_(2)O_(2) system was verified.This work provides meaningful guidance for the cheap and convenient design of nanoreactors for Fenton-like applications.
基金the National Natural Science Foundation of China(Nos.51935014,51905553,81871494,81871498,51705540)the Hunan Provincial Natural Science Foundation of China(Nos.2019JJ50774,2018JJ3671 and 2019JJ50588)+5 种基金the Jiang Xi Provincial Natural Science Foundation of China(No.20192ACB20005)the Guangdong Province Higher Vocational Colleges&Schools Pearl River Scholar Funded Scheme(2018)the Open Sharing Fund for the Large-scale Instruments and Equipments of Central South Universitythe Project of Hunan Provincial Science and Technology Plan(No.2017RS3008)the Hunan Provincial Innovation Foundation For Postgraduate(No.CX2018B093)the Fundamental Research Funds for the Central Universities of Central South University(Nos.2018zzts022 and 2019zzts725)。
文摘It is challenging for antibacterial polymer scaffolds to achieve the drug sustained-release through directly coating or blending.In this work,halloysite nanotubes(HNTs),a natural aluminosilicate nanotube,were utilized as a nano container to load nano silver(Ag)into the lumen through vacuum negativepressure suction&injection and thermal decomposition of silver acetate.Then,the nano Ag loaded HNTs(HNTs@Ag)were introduced to poly-l-lactic acidide)(PLLA)scaffolds prepared by additive manufacturing for the sustained-release of Ag^+.Acting like a’shield’,the tube walls of HNTs not only retarded the erosion of external aqueous solution on internal nano Ag to generate Ag^+but also postponed the generated Ag^+to diffuse outward.The results indicated the PLLA-HNTs@Ag nanocomposite scaffolds achieved a sustained-release of Ag^+over 28 days without obvious initial burst release.Moreover,the scaffolds exhibited a long-lasting antibacterial property without compromising the cytocompatibility.Besides,the degradation properties,biomineralization ability and mechanical properties of the scaffolds were increased.This study suggests the potential application of inorganic nanotubes as drug carrier for the sustained-release of functional polymer nanocomposite scaffolds.
基金financially supported by the National Natural Science Foundation of China(No.21673051)the Department of Science and Technology of Guangdong Province,China(No.2019A050510043)。
文摘All-solid-state lithium batteries(ASSLB) are promising candidates for next-generation energy storage devices.Nevertheless,the large-scale commercial application of high energy density AS S LB with the polymer electrolyte still faces challenges.In this study,a thin solid polymer composite electrolyte(SPCE) is prepared through a facile and cost-effective strategy with an infiltration of thermoplastic polyurethane(TPU),lithium salt(LiTFSI or LiFSI),and halloysite nanotubes(HNTs) in a porous framework of polyethylene separator(PE)(TPU-HNTs-LiTFSI-PE or TPU-HNTs-LiFSI-PE).The composition,electrochemical performance,and especially the effect of anions(TFSI-and FSI-) on cycling performance are investigated.The results reveal that the flexible TPU-HNTs-LiTFSI-PE and TPU-HNTs-LiFSI-PE with a thickness of 34 μm exhibit wide electrochemical windows of 4.9 and 5.1 V(vs.Li+/Li) at 60℃,respectively.Reduction in FSI-tends to form more LiF and sulfur compounds at the interface between TPU-HNTs-LiFSI-PE and Li metal anode,thus enhancing the interfacial stability.As a result,cell composed of TPU-HNTs-LiFSI-PE exhibits a smaller increase in interfacial resistance of solid electrolyte interphase(SEI) with a distinct decrease in charge-transfer resistance during cycling.Li|Li symmetric cell with TPU-HNTs-LiFSI-PE could keep its stable overpotential profile for nearly 1300 h with a low hysteresis of approximately39 mV at a current density of 0.1 mA cm-2,while a sudden voltage rise with internal cell impedance-surge signals was observed within 600 h for cell composed of TPU-HNTs-LiTFSI-PE.The initial capacities of NCMITPU-HNTs-LiTFSIPEILi and NCMITPU-HNTs-LiFSI-PEILi cells were 149 and 114 mAh g-1,with capacity retention rates of 83.52% and89.99% after 300 cycles at 0.5 C,respectively.This study provides a valuable guideline for designing flexible SPCE,which shows great application prospect in the practice of ASSLB.
基金supported by the National Natural Science Foundation of China (NSFC,Nos.42061134018,42011530085 and 41877323)the Russian Science Foundation (RSF,No.21-4700019,Russia)the Sichuan Science and Technology Program (No.2019JDJQ0056,China)。
文摘Various enzymatic reactions or enzymatic cascade reactions occur efficiently in biological microsystems due to space constraints or orderly transfer of intermediate products. Inspired by this, the horseradish peroxidase(HRP)-like nanozyme(Fe-aminoclay) was in situ synthesized on the surface of alkali-activated halloysite nanotubes and the natural enzyme(glucose oxidase, GOx) was immobilized on it to construct a high-efficiency GOx-Fe AC@AHNTs cascade nanoreactor. In which, Fe AC@AHNTs can not only be used as a carrier for immobilized enzymes, but also help its catalytic activity to cooperate with glucose oxidase in a cascade reaction. The microcompartments and substrate channel effect of this enzyme-nanozyme microsystem exhibit a superior catalytic performance than that of natural enzyme system, and exhibits excellent long-term stability and recyclability. Subsequently, the GOx-Fe AC@AHNTs cascade nanoreactor was employed as a glucose colorimetric platform, which displayed a low detection limit(0.47 μmol/L)in glucose detection. This enzyme-nanoenzyme nanoreactor provides a simple and effective example for constructing a multi-enzyme system with limited space, and lays the foundation for subsequent research in the fields of biological analysis and catalysis.
基金financially supported by the National Natural Science Foundation of China(No.52073047)the Program of Shanghai Academic/Technology Research Leader(No.20XD1433700)+3 种基金the International Cooperation Fund of the Science and Technology Commission of Shanghai Municipality(No.20520740800)the Innovation Program of Shanghai Municipal Education Commission(No.2017–01–07–00–03-E00055)the Science and Technology Commission of Shanghai Municipality(No.20JC1414900)the China Postdoctoral Science Foundation(Nos.2019M661323 and 2020TQ0062)。
文摘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.
文摘Targeted drug delivery systems have attracted a great deal of interest by virtue of their potential use in chemotherapy. In this study, multicomponent halloysite nanotubes （HNTs） have been evaluated as a platform to assist and direct the delivery of anticancer drug doxorubicin （DOX） into cancer cells. Folic acid （FA） and magnetite nanopar- ticles were successfully grafted onto HNTs via amide reaction whereas the drug has been introduced by capitalizing electrostatic interaction between cationic drug and anionic exterior of HNTs, which eventually leads to pH respon- sive release. The resultant DOX loaded FA-Fe304@HNTs were well characterized by transmission electron mi- croscopy （TEM）, scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FTIR） and XRD. The clinical efficacy of the system was validated by confocal microscopy and cell cytotoxicity assay （MTT assay）. MTT assay results revealed a high biocompatibility up to a concentration of 200 μg/mL of HNTs, while, DOX loaded FA-Fe304@HNTs were markedly cytotoxic to HeLa cells. This multifunctional nanovehicle has a great po- tential for cancer diagnosis and therapy, and could further advance the clinical use of nanomedicine.
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0302300)the International Collaboration Programs of Guangdong Province(No.2020A0505100010)+4 种基金the Fundamental Research Funds for the Central Universities(No.2019MS062)the Natural Science Foundation of Guangdong Province(No.2021A1515012425)the Overseas Famous Scholar Funds of Guangdong Province(No.2020A1414010372)City University of Hong Kong(No.9678103)the Opening Project of Key Laboratory of Polymer Processing Engineering(South China University of Technology),Ministry of Education of China(No.KFKT1904)。
文摘Halloysite nanotubes(HNTs)have been considered as a promising flame retardant fillers for polymers.In this work,the polyhedral oligomericsilsesquioxane(POSS)containing amino group was covalently grafted on the surface of HNTs with 3-(2,3-epoxypropoxy)propytrimethoxysilane as a chemical bridge.The POSS modified HNTs(HNTs-POSS)dispersed uniformly in the thermoplastic polyurethane(TPU)matrix and endowed TPU nanocomposites with enhanced tensile properties and fire safety.Cone calorimeter tests revealed that the introduction of 2 wt%HNTs-POSS to TPU matrix remarkably reduced the peak of heat release rate(PHRR)and total heat release(THR)by 60.0%and 18.3%,respectively.In addition,the peak CO production rate and total smoke release(TSR)could be significantly suppressed by the addition of HNTsPOSS.The well dispersed HNTs in combination with the ceramified silicon network from the thermal decomposition of POSS contributed to the formation of a continuous and compact char layer,exhibiting a tortuous effect by inhibiting heat diffusion and evaporation of volatile gaseous.In addition,the released crystal water from HNTs could dilute the combustible volatiles and then decline the combustion intensity.The tensile tests demonstrated that introduction of 2 wt%HNTs-POSS would enhance the maximum stress of TPU nanocomposite with a slight decrease of elongation at break.The combination of HNTs and POSS through the construction of effective interfacial interactions provides a feasible way to effectively enhance the fire safety of TPU nanocomposites without scarifying ductility.
文摘Introducing inorganic nanomaterials into a polymer matrix greatly improves the anticorrosion performance of epoxy coatings(EP);however,poor compatibility between the materials can limit the improvement in properties.In this work,based on the high interface compatibility of two-dimensional(2D)Co_(2)(OH)_(2)BDC(BDC=1,4-benzenedicarboxylate)in the epoxy coating that we reported in previous work,we fabricated a 2D Co_(2)(OH)_(2)BDC-halloysite nanotube(HNT)nanocomposite have a structure consisting of alternating of nanosheets and nanotube by in situ synthesis.The nanocomposite was characterized by Fourier transform infrared spectroscopy,X-ray diffraction,and scanning electron microscopy.The mechanical and anticorrosion performance of the 2D Co_(2)(OH)_(2)BDC-HNT/EP coating was evaluated by mechanical tests and electrochemical impedance spectroscopy spectra.Compared with a conventional unreinforced epoxy coating,the 2D Co_(2)(OH)_(2)BDC-HNT/EP coating had higher mechanical strength and toughness,and the low-frequency impedance modulus of 2D Co_(2)(OH)_(2)BDC-HNT/EP coating was increased by three orders of magnitude,demonstrating the high corrosion resistance of our reinforced coating.
文摘Halloysite nanotubes were used as nanocontainers to hold corrosion inhibitors such as Ce^(3+)-Zr^(4+),2-mercaptobenzothiazole and 8-hydroxyquinoline in their lumen.An acid assisted etching of the nanotubes was carried out with a view to increase the lumen diameter and thereby,increase the amount of loading of the corrosion inhibitor.The morphology of as-received and etched halloysite nanotubes was ob-served using TEM analysis.The loading of corrosion inhibitors was confirmed using SEM-EDS and BET analysis.Polymeric microcapsules were used as capping agents for the ends of the loaded HNTs following which,they were dispersed into a hybrid sol-gel silica matrix.Dip coating method was used to generate coatings on AZ91D substrates followed by heat treatment at 130℃ for 1 h.The release rate kinetics of corrosion inhibitors from as-received and etched nanotubes was investigated in buffer solutions of 3.5 wt%NaCl at different pH.The release mechanism of corrosion inhibitors from the HNT lumen was validated using various semi-empirical models.Coatings were also evaluated for their corrosion protection ability using electrochemical techniques after exposure to 3.5 wt%NaCl solution for 120 h.Coatings generated using Ce^(3+)-Zr^(4+)loaded into as-received halloysite nanotubes have shown more effective corrosion protection when compared to other corrosion inhibitors after 120 h exposure to the corrosive medium.
基金supported by the National Natural Science Foundation of China(Nos.50573021 and 50603005)
文摘A natural nanotubular material,halloysite nanotubes(HNTs),was introduced to prepare styrene-butadiene rubber/modified halloysite nanotube(SBR/m-HNT) nanocomposites.Complex of resorcinol and hexamethylenetetramine (RH) was used as the interfacial modifier.The structure,morphology and mechanical properties of SBR/m-HNT nanocomposites,especially the interfacial interactions,were investigated.SEM and TEM observations showed that RH can not only facilitate the dispersion and orientation of HNTs in SBR matrix at ...
基金supported by the National Natural Science foundation of China (21073238)the National Basic Research Program of China(2011CB211704)the Special Fund for Basic Scientific Research of Central Colleges,South-Central University for Nationalities
文摘Novel cobalt Fischer-Tropsch synthesis （FTS） catalysts were prepared from natural halloysite nanotubes （HNT） by double-solvent and wet- impregnation methods, and characterized by TEM, XRD, TPR and N2 adsorption-desorption. Comparing with the catalyst prepared by wet- impregnation method, the catalyst prepared by double-solvent method reduces Co3O4 particle migration and agglomeration due to size-induced effect, thus showing higher catalytic activity for Fischer-Tropsch synthesis.
基金Supported by the National ]qatural Science Foundation of China （20906064）, the National Basic Research Program of China （2009CB623407）, the Program for Changjiang Scholars and Innovative Research Team in University （IRTl163）, and the Foundation for the Author of National Excellent Doctoral Dissertation of China （201163）.
文摘Halloysite nanotube-composited thermo-responsive hydrogel system has been successfully developed for controlled drug release by copolymerization of N-isopropylacrylamide （NIPAM） with silane-modified halloysite nanotubes （HNT） through thermally initiated free-radical polymerization. With methylene blue as a model drug, thermo-responsive drug release results demonstrate that the drug release from the nanotubes in the composited hy-drogel can^be well controlled by manipulating the environmental temperature. When the hydrogel network is swol- len at temperature below the lower critical solution temperature （LCST）, drug releases steadily from lumens of the embedded nanotubes, whereas the drug release stops when hydrogel shrinks at temperature above the LCST. The release of model drug from the HNT-composited hydrogel matches well with its thermo-responsive volume phasetransition, and shows characteristics of well controlled release. The design strategy and release results of the pro- posed novel HNT-composited thermo-responsive hydrogel system provide valuable guidance for designing respon- s_i_ve nanocomposites for controlled-release of active agents.
基金the financial support from Erasmus Mundus program(20132445,2016)(Battuta project)financed by the European Commission between Riga Technical University and Cadi Ayyad University of Marrakech.
文摘This work reports a comprehensive study on poly(Ethylmethacrylateco-Acrylonitrile)Poly(EMA-AN)nanocomposites reinforced with a hybrid mixture of nanoreiforcements based on nanocrystals of cellulose(NCC)(1 or 5%wt)and halloysite nanotubes(HNTs)(1 or 5%wt).The morphology,thermal and mechanical properties of these nanocomposites were characterized.Homogeneous dispersion of the nanofillers has been shown by scanning electron microscopy.A significant increase of the rubbery modulus and glass transition temperature were obtained upon filler addition,due to the reduction of mobility of the matrix macromolecular chains.On the other hand,compared with the neat Poly(EMAAN),the storage modulus of the nanocomposites increased by a factor 38 when adding 5 wt%NCC and by 17 for the same concentration of HNTs.mechanical properties of ternary nanocomposites were furthers increased resulting from a synergistic effect of these two nanofillers.
文摘This study presents the modification of surfaces of nanoclays, halloysite nanotubes (HNT) and sepiolite (SEP), with styrene-maleic anhydride copolymers (SMA) via esterification reaction between hydroxyl groups of the nanoclays and anhydride groups of SMA. The structural, thermal, and morphological analyses of the modified nanoclays were performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermal gravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). All of these results suggested that the expected modification of HNT and SEP surfaces were performed. Although XRD patterns of HNT containing samples showed that the basal spacing shifted to higher distances, it was found that those of the crystalline structure of SEP remained unchanged. Thermal gravimetric analysis exhibited that SMA copolymers were grafted onto the surfaces of nanoclays varying amounts between 15 and 43 wt. % depending on the types of nanoclays and SMA copolymers. This modification indicates that these nanoclays can be added to the polystyrene matrix without any compatibilizers.
基金The authors acknowledge the financial and laboratory support provided by UTP via YUTP research grantMechanical Engineering Department of Universiti Teknologi PETRONAS,Malaysia for this study
文摘In this study, the effects of halloysite nanotubes （HNTs） reinforcement in expandable graphite based intumescent fire retardant coatings （IFRCs） developed using a polydimethylsiloxane （PDMS）/phenol BA epoxy system were investigated. Intumescent coating formulations were developed by incorporating different weight percentages of HNTs and PDMS in basic intumescent ingredients （ammonium polyphosphate/melamine/boric acid/expandable graphite, APP/MEL/BA/EG）. The performance of intumescent formulations was investigated by furnace fire test, Bunsen burner fire test, field emission electron microscopy （FESEM）, thermogravimetric analysis （TGA）, transmission electron microscopy （TEM）, and Fourier transform infrared analysis （FTIR）. The Bunsen burner fire test results indicated that the fire performance of HNTs and PDMS reinforced intumescent formulation has improved due to the development of silicate network over the char residue. Improved expansion in char residue was also noticed in the formulation, SH（3）, due to the minimum decomposition of char carbon. FESEM and TEM results validated the development of silicate network over char layer of coating formulations. A considerable mass loss difference was noticed during thermal gravimetric analysis （TGA） of intumescent coating formulations. Reference formulation, SH（0） with no filler, degraded at 300 ~C and lost 50% of its total mass but SH（3）, due to synergistic effects between PDMS and HNTs, degraded above 400 ~C and showed the maximum thermal stability. XRD analysis showed the development of thermally stable compound mulltie, due to the synergism of HNTs and siloxane during intumescent reactions, which enhanced fire performance. FTIR analysis showed the presence of incorporated siloxane and silicates bonds in char residue, which endorsed the toughness of intumescent char layer produced. Moreover, the synergistic effect ofHNTs, PDMS, and other basic intumescent ingredients enhanced the polymer cross-linking in binder system and improved fire resistive performance of coatings.
基金supported by the National Natural Science Foundation of China(No.22178120)the Guangdong Natural Science Funds for Distinguished Young Scholar(No.2017A030306022)Guangzhou Technology Project(No.202002030164)。
文摘Coating inorganic ceramic particles on commercial polyolefin separators has been considered as an effective strategy to improve thermostability of separator.However,the introduction of the coating layer could induce pore blockage on the surface of the polyolefin separator.Herein,a ceramic composite layer that consists of alumina nanoparticles(n-Al_(2)O_(3))and halloysite nanotubes(HNTs)is designed to modify the polyethylene(PE)separator(the modified separator is denoted as AH-PE).The HNTs with hollow nanotubular structure construct a light skeleton and provide fast ion transport channels while Al_(2)O_(3)particles function as heat-resistant fillers to inhibit the shrinkage of the separator at elevated temperatures.The total thickness of AH-PE separator is only 14μm.Consequently,the mass increment of AH-PE separator decreases from 5 g/m^(2)to 3.5 g/m^(2),and the Gurley value reduces by 23%,compared with Al_(2)O_(3)coated PE separator(A-PE).Due to the synergistic effects of Al_(2)O_(3)and HNTs,AH-PE separator exhibits highly improved thermal stability(almost no shrinkage at 170℃for 30 min),high Li^(+)transference number(up to 0.47),and long cycle life of 450 h for Li|Li cells.Moreover,the Li Fe PO_(4)/Li cells assembled with AH-PE separators demonstrate improved rate capability and safety performance.
文摘Tendon and ligament injuries are the most common musculoskeletal injuries,which not only impact the quality of life but result in a massive economic burden.Surgical interventions for tendon/ligament injuries utilize biological and/or engineered grafts to reconstruct damaged tissue,but these have limitations.Engineered matrices confer superior physicochemical properties over biological grafts but lack desirable bioactivity to promote tissue healing.While incorporating drugs can enhance bioactivity,large matrix surface areas and hydrophobicity can lead to uncontrolled burst release and/or incomplete release due to binding.To overcome these limitations,we evaluated the delivery of a peptide growth factor(exendin-4;Ex-4)using an enhanced nanofiber matrix in a tendon injury model.To overcome drug surface binding due to matrix hydrophobicity of poly(caprolactone)(PCL)-which would be expected to enhance cell-material interactions-we blended PCL and cellulose acetate(CA)and electrospun nanofiber matrices with fiber diameters ranging from 600 to 1000 nm.To avoid burst release and protect the drug,we encapsulated Ex-4 in the open lumen of halloysite nanotubes(HNTs),sealed the HNT tube endings with a polymer blend,and mixed Ex-4-loaded HNTs into the polymer mixture before electrospinning.This reduced burst release from~75%to~40%,but did not alter matrix morphology,fiber diameter,or tensile properties.We evaluated the bioactivity of the Ex-4 nanofiber formulation by culturing human mesenchymal stem cells(hMSCs)on matrix surfaces for 21 days and measuring tenogenic differentiation,compared with nanofiber matrices in basal media alone.Strikingly,we observed that Ex-4 nanofiber matrices accelerated the hMSC proliferation rate and elevated levels of sulfated glycosaminoglycan,tendon-related genes(Scx,Mkx,and Tnmd),and ECM-related genes(Col-Ⅰ,Col-Ⅲ,and Dcn),compared to control.We then assessed the safety and efficacy of Ex-4 nanofiber matrices in a full-thickness rat Achilles tendon defect with histology,marker expression,functional walking track analysis,and mechanical testing.Our analysis confirmed that Ex-4 nanofiber matrices enhanced tendon healing and reduced fibrocartilage formation versus nanofiber matrices alone.These findings implicate Ex-4 as a potentially valuable tool for tendon tissue engineering.
