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1.
《Ceramics International》2020,46(12):20306-20312
Although the antibacterial properties of MXene nanosheets containing Ti3C2Tx are known, their antifungal properties have not been well studied. Herein, we present for the first time a report on the antifungal properties of Ti3C2Tx MXene. The Ti3C2Tx MXene was obtained by first exfoliating MAX phase of Ti3AlC2 with concentrated hydrofluoric acid, then the Ti3C2Tx was intercalated and deliminated by ethanol treatment and ultrasonication process. The delaminated Ti3C2Tx MXene nanosheets (d-Ti3C2Tx) were characterized using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), X-ray diffraction spectroscopy (XRD), and Raman spectroscopy. It was found that Ti3C2Tx MXene was characterized by lamellar structure alternating with layers of Ti, Al and C. The EDX results revealed that the delaminated Ti3C2Tx MXene nanosheets were composed of Ti, C, Si, O, F, and a trace amount of Al. The XRD and Raman spectra further indicated the elimination of Al and the formation of two-dimensional Ti3C2Tx MXene nanosheets. The antifungal activity of the delaminated Ti3C2Tx MXene was determined against Trichoderma reesei using the modified agar disc method. Observation using inverted phase contrastmicroscopy revealed inhibited fungus growth with the absence of hyphae around the discs treated wtih MXene. The surrounding of the control groups without an inclusion of MXene was found with large number of hyphae and spores. In addition, the spores of the fungi treated with the samples containing d-Ti3C2Tx MXene nanosheets did not germinate even after 11 days of culture. The results demonstrated disruption to the hemispheric structural formation of fungi colony, inhibition of hyphae growth and cell damage for fungi grown on the d-Ti3C2Tx MXene nanosheets. These new findings suggest that d-Ti3C2Tx MXene nanosheets developed in this work could be a promising anti-fungi material.  相似文献   

2.
The nanocomposite films comprising polymer blends of poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), poly(ethylene oxide) (PEO), and poly(ethylene glycol) (PEG) with montmorillonite (MMT) clay as nanofiller were prepared by aqueous solution casting method. The X‐ray diffraction studies of the PVA–x wt % MMT, (PVA–PVP)–x wt % MMT, (PVA–PEO)–x wt % MMT and (PVA–PEG)–x wt % MMT nanocomposites containing MMT concentrations x = 1, 2, 3, 5 and 10 wt % of the polymer weight were carried out in the angular range (2θ) of 3.8–30°. The values of MMT basal spacing d001, expansion of clay gallery width Wcg, d‐spacing of polymer spherulite, crystallite size L and diffraction peak intensity I were determined for these nanocomposites. The values of structural parameters reveal that the linear chain PEO and PEG in the PVA blend based nanocomposites promote the amount of MMT intercalated structures, and these structures are found relatively higher for the (PVA–PEO)–x wt % MMT nanocomposites. It is observed that the presence of bulky ester‐side group in PVP backbone restricts its intercalation, whereas the adsorption behavior of PVP on the MMT nanosheets mainly results the MMT exfoliated structures in the (PVA–PVP)–x wt % MMT nanocomposites. The crystallinities of the PEO and PEG were found low due to their blending with PVA, which further decreased anomalously with the increase of MMT concentration in the nanocomposites. The decrease of polymer crystalline phase of these materials confirmed their suitability in preparation of novel solid polymer nanocomposite electrolytes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40617.  相似文献   

3.
《Ceramics International》2020,46(17):27326-27335
High-dielectric-constant (high-k) polymer/conductor composites with low dielectric loss are desirable for energy storage. However, high leakage currents from interfacial regions with high charge density are difficult to handle. In this work, high permittivity and low dielectric loss were achieved in poly(vinyl alcohol) (PVA)/V2C MXene nanocomposite films fabricated by solution casting by taking advantage of the interfacial compatibility and moderate interfacial charge density of the nanocomposites. Water-soluble PVA was utilized as the polymer matrix. Delaminated V2C MXene nanosheets with appropriate conductivity were prepared and used as the filler. The mild interface polarization of the nanocomposites was responsible for achieving favourable permittivity values. The small gap between the work functions of PVA and V2C contributed to moderate interfacial charge density values and thus low dielectric loss values. A proportional correlation between the interfacial charge density and the conductivity of composites was also verified. The depth of charge injection from the MXene to PVA was found to be half of the interlamellar spacing of the delaminated MXene. The dependence of the electrical properties of the nanocomposites on the frequency and MXene content was also studied. The composite with 4 wt% MXene exhibited a permittivity of ~24 (16 times that of PVA) and a dielectric loss of ~0.14 (1.5 times that of PVA) at 1 kHz, as well as breakdown strength of ~31 MV m−1 (63% of PVA). This work might enable environmentally friendly fabrication of promising composite dielectrics.  相似文献   

4.
Glassy polymer nanofibers with spatially confined poly(ethylene oxide) (PEO) were fabricated by coaxial electrospinning of PEO with polyacrylonitrile (PAN) or polystyrene. The effect of melt‐annealing on the crystallization behavior of the confined PEOs was studied using differential scanning calorimetry. It is found that the crystallization behavior of the confined PEOs varies with annealing temperature (Ta), annealing time (ta), and molecular weight of PEO. Notably, it is observed that the crystallization temperature (Tc) and melting temperature (Tm) of PEO increase with prolongation of ta, for PEO600K/PAN and PEO2K/PAN coaxial electrospun fibers. This phenomenon can be interpreted by the annealing‐induced demixing at the core‐sheath interface. After the coaxial electrospinning, the core and sheath of the PEO/PAN coaxial fibers are partially compatible due to the miscible solvents used for the core and sheath polymers. Upon annealing, demixing occurs at the core‐sheath interface, leading to improved crystallizability of PEO. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45760.  相似文献   

5.
We undertook this study to understand reinforcement mechanism of short cellulose nanocrystals (CNCs) and long cellulose nanofibrils (CNFs) as compatibility agents for improving the interfacial miscibility of poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) blends. The effects of the two cellulose nanofibers on the morphological, mechanical, and thermal properties of the polymer blends were compared systematically. The light transparency, scanning electron microscopy, and Fourier transform infrared results show that nanocellulose between PVA and PEO eliminated the negative effects generated by the immiscible interface through increased hydrogen bonding. Thermogravimetric analysis and differential scanning calorimetry results show that crystalline region reorganization around the interface facilitated the shift of the polymer blends from multiple phases to a homogeneous phase. According to the Halpin‐Kardos and Quali models, we assumed that the potential for repairing the immiscible interface would have a larger effect than the potential of reinforcement. At the same concentration, polymer blends with CNCs showed greater light transparency, strength, modulus, and crystal structure than with those with CNFs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45896.  相似文献   

6.
《Ceramics International》2022,48(11):15721-15728
Developing a new strategy to effectively prevent the restacking of MXene nanosheets will have significant impacts on designing flexible supercapacitor electrodes. Herein, a novel Ti3C2Tx/polyvinyl alcohol (PVA) porous sponge with 3D interconnected structures is prepared by sol-gel and freeze-dried methods. This Ti3C2Tx/PVA porous sponge is used as the template of in-situ polyaniline (PANI) polymerization, and the fabricated PANI@Ti3C2Tx/PVA hydrogel composite is applied as flexible supercapacitors electrodes. 1D conductive polymer chains PVA could increase the interlayer spacing of Ti3C2Tx nanosheets, which is beneficial to expose more electrochemical active sites. The supercapacitor based on PANI@Ti3C2Tx/PVA hydrogel composite exhibits the coexistence of double-layer capacitance and pseudocapacitance behavior. This supercapacitor shows a maximum areal specific capacitance of 103.8 mF cm?2 at 2 A m?2, and it also exhibits a maximum energy density of 9.2 μWh·cm?2 and an optimum power density of 800 μW cm?2. The capacitance of this supercapacitor is almost not change under different bending angles. Moreover, 99% capacitance retention is achieved after 10 000 charge/discharge cycles of the supercapacitor. The synergistic effect between PANI and Ti3C2Tx/PVA composite may improve the number of reactive sites and provide efficient channels for ion diffusion/electron transport.  相似文献   

7.
Mixed rutile–anatase TiO2 nanoparticles were synthesized by hydrothermal treatment under acidic conditions and incorporated into poly(vinyl alcohol) (PVA). These nanocomposites were electrospun to produce nanofibers of PVA/TiO2, which were characterized by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The photocatalytic degradation of Rhodamine B and degradation of the polymer by UV‐C lamps were also investigated. The results showed that TiO2 nanoparticles did not change the morphology and thermal behavior of the nanofiber polymer, but were effective in modifying the UV absorption of PVA without reducing its stability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

8.
The dehydrochlorination of poly(vinyl chloride) (PVC) film samples modified with titanium dioxide (TiO2)/poly(ethylene oxide) (PEO) based paint photocatalysts [the addition of methyl linoleate (ML) or methyl oleate (MO)] was performed. After 24 h of UV photoirradiation, the sample with TiO2/PEO showed that there existed a structure with the longest polyene length, whereas that with TiO2/PEO/ML contained the most polyene structures. The chloroform‐soluble fraction of the sample with TiO2/PEO contained a poly(vinyl alcohol) (PVA) structure instead of a polyene one and showed a novel method of PVA production via PVC photodegradation. The molecular weight curve of the fraction shifted slightly to a lower molecular weight compared to that without the photocatalyst; this showed that slight polymer chain scission occurred. The 1H‐NMR and 13C‐NMR spectra showed that the content of PVA units was about 20%, and the PVA sequence was blocky. The fraction of the sample with TiO2/PEO/ML contained the highest methyl group content; this showed that the branch degree was highest as was the polyene content. These highest contents were due to the existence of the grafted ML. Pyrolysis gas chromatography/mass spectroscopy measurements suggested that there existed more polyene and graft units in the chloroform‐insoluble fractions of the samples with TiO2/PEO, TiO2/PEO/ML, and TiO2/PEO/MO, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40760.  相似文献   

9.
《Ceramics International》2023,49(5):7258-7265
The (001)TiO2/Ti3C2 MXene heterojunction photocatalyst was prepared with the hydrothermal oxidation method by using the two-dimensional Ti3C2 MXene as the substrate. The formation of TiO2 surface heterojunctions, Schottky junctions at the interface between (001) facets TiO2 and Ti3C2 MXene, and the local surface plasmon resonance effect of plasma Ti3C2 MXene combine together to promote the effective separation of electrons and holes after photoexcitation. After 150 min of near infrared light irradiation and sunlight irradiation, the degradation rates of tetracycline by (001)TiO2/Ti3C2 MXene photocatalyst are 28.63% and 52.74%, respectively, with near infrared light and full spectrum degradation characteristics. Our work is expected to provide a valuable reference for the design of MXene based full spectrum photocatalysts.  相似文献   

10.
《Ceramics International》2022,48(5):6338-6346
The potential of two-dimensional layered MXenes in electromagnetic wave (EMW) absorption needs further development. Herein, we carried out the in situ growth of carbon nanotubes (CNTs) on the surface of Ti3C2Tx MXene at ultra-low temperature via chemical vapor deposition. The obtained CNTs exhibited a bamboo-like structure and were accompanied by helical carbon nanofibers. The ultra-low temperature solved the problem that the high temperature required in the traditional CNT growth process would destroy the structural integrity of MXene. The lush CNT forest cross-linked the MXene layers, transforming the two-dimensional layered structure into a three-dimensional conductive network, providing abundant conductive channels for carriers, optimizing the impedance matching of the CNT/MXene hybrid, and resulting in a significant dielectric loss. The as-prepared CNT/MXene hybrid exhibited a minimal reflection loss of ?52.56 dB (99.9994% EMW absorption) in the X-band. This work proposes a new idea to enhance the EMW absorption properties of Ti3C2Tx MXene and fabricate high-performance MXene-based EMW absorbers.  相似文献   

11.
Ti3C2Tx MXene, an emerging two-dimensional (2D) ceramic material, has rich interfaces and strong conductive networks. Herein, we have successfully built a heterostructure between Ti3C2Tx MXene and WS2 to improve electromagnetic absorption performance. X-ray diffraction and X-ray photoelectron spectroscopy were used to determine the successful synthesis of Ti3C2Tx/WS2 composite. Field emission scanning electron microscopy and transmission electron microscopy images show that WS2 nanosheets are evenly dispersed on the accordion-like Ti3C2Tx MXene. Importantly, Ti3C2Tx MXene/WS2 composite has sufficiently high dielectric loss and impedance matching due to self-adjusting conductivity and 2D heterostructure interfaces. As a result, the Ti3C2Tx/WS2 composite has a minimum reflection loss (RLmin) of −61.06 dB at 13.28 GHz. Besides, it has a broad effective absorption bandwidth (EAB) of 6.5 GHz, with EAB >5.0 GHz covering a wide range of thickness. Such impressive results may provide experience for the application of Ti3C2Tx ceramics and 2D materials.  相似文献   

12.
Chitosan/poly(vinyl alcohol) (PVA) nanofibers with antibacterial activity were prepared by the electrospinning of a chitosan/PVA solution with a small amount of silver nitrate (AgNO3) and titanium dioxide (TiO2). Nanofibers with diameters of 270–360 nm were obtained. The yield of low‐viscosity chitosan (LCS)/PVA nanofibers was higher than that of high‐viscosity chitosan (HCS)/PVA, and the water content of the HCS/PVA nanofibers and the LCS/PVA nanofibers were 430 and 390%, respectively. The nanofibers developed in this study exhibited antibacterial activities of 99 and 98% against Staphylococcus aureus and Escherichia coli, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

13.
《Ceramics International》2019,45(16):19902-19909
Two-dimensional (2D) MXenes have attracted much attention due to their unique structural characteristics and novel performance in a variety of functions. The fabrication of 2D Ti3C2 MXene by acid etching usually requires a long period of over 10 h. In this work, we report on the rapid preparation, thermal stability and electromagnetic interference (EMI) shielding effectiveness of 2D Ti3C2 MXene. With the processing conditions optimized by adjusting the etching time and temperature, Ti3C2 MXene with a scattered accordion-like structure has been successfully achieved by etching Ti3AlC2 powders with 40% HF at 50 °C for only 0.5 h. The as-synthesized Ti3C2 was stable at temperatures up to 300 °C in air, but stable in vacuum at temperatures up to 800 °C. The as-synthesized Ti3C2 MXene has good EMI shielding performance. The total shielding effectiveness of Ti3C2 in a WAX matrix exceeded 20 dB in the whole frequency ranging from 2 to 18 GHz. The maximum shielding effectiveness value achieved to 34 dB at 18 GHz as the Ti3C2 content was up to 70 wt%. This work provides an approach for the large scale preparation of the Ti3C2 MXene.  相似文献   

14.
A new poly(propylene carbonate)/poly(ethylene oxide) (PEO/PPC) polymer electrolytes (PEs) have been developed by solution‐casting technique using biodegradable PPC and PEO. The morphology, structure, and thermal properties of the PEO/PPC polymer electrolytes were investigated by scanning electron microscopy, X‐ray diffraction, and differential scanning calorimetry methods. The ionic conductivity and the electrochemical stability window of the PEO/PPC polymer electrolytes were also measured. The results showed that the Tg and the crystallinity of PEO decrease, and consequently, the ionic conductivity increases because of the addition of amorphous PPC. The PEO/50%PPC/10%LiClO4 polymer electrolyte possesses good properties such as 6.83 × 10?5 S cm?1 of ionic conductivity at room temperature and 4.5 V of the electrochemical stability window. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

15.
Most of the ancient buildings are made of inflammable wooden structures, which have serious potential safety hazards. Applying fire-retardant coating is one of the simplest and most effective means of fire prevention in ancient wooden buildings. In this work, we have demonstrated that the Ti3C2Tx transition metal carbide/carbonitride (MXene) was applied as the synergetic agent, waterborne epoxy resin as the film-forming agent, ammonium polyphosphate, dipentaerythritol, and melamine (P-C-N system) as the intumescent fire-retardant system to prepare Ti3C2Tx/epoxy intumescent fire-retardant coating (TEIFC). The results showed that MXene has significantly improved the fire-retardant performance of the coating. By incorporating 3 wt% Ti3C2Tx (TEIFC-3, with 62 wt% P-C-N system), the coating displayed UL-94 V-0 rating with the limiting oxygen index value of 38%. In addition, the combination of Ti3C2Tx and P-C-N system enhanced the Shore hardness of the coating to 95 SHD (TEIFC-3). Furthermore, TEIFC-3 presented high thermal stability with the THRI of 177.0°C and Tdmax of 380.5°C. This work provides a novel strategy for the design and preparation of intumescent fire-retardant coating, which will greatly broaden the industrial applications of MXene-based polymer composites in the field of fire prevention of ancient buildings.  相似文献   

16.
Solvents and electrolytes play an important role in the fabrication of dye‐sensitized solar cells (DSSCs). We have studied the poly(ethylene oxide)‐poly(methyl methacrylate)‐KI‐I2 (PEO‐PMMA‐KI‐I2) polymer blend electrolytes prepared with different wt % of the 2‐mercaptopyridine by solution casting method. The polymer electrolyte films were characterized by the FTIR, X‐ray diffraction, electrochemical impedance and dielectric studies. FTIR spectra revealed complex formation between the PEO‐PMMA‐KI‐I2 and 2‐mercaptopyrindine. Ionic conductivity data revealed that 30% 2‐mercaptopyridine‐doped PEO‐PMMA‐KI‐I2 electrolyte can show higher conductivity (1.55 × 10?5 S cm?1) than the other compositions (20, 40, and 50%). The effect of solvent on the conductivity and dielectric of solid polymer electrolytes was studied for the best composition (30% 2‐mercaptopyridine‐doped PEO‐PMMA‐KI‐I2) electrolyte using various organic solvents such as acetonitrile, N,N‐dimethylformamide, 2‐butanone, chlorobenzene, dimethylsulfoxide, and isopropanol. We found that ac‐conductivity and dielectric constant are higher for the polymer electrolytes processed from N,N‐dimethylformamide. This observation revealed that the conductivity of the solid polymer electrolytes is dependent on the solvent used for processing and the dielectric constant of the film. The photo‐conversion efficiency of dye‐sensitized solar cells fabricated using the optimized polymer electrolytes was 3.0% under an illumination of 100 mW cm?2. The study suggests that N,N‐dimethylformamide is a good solvent for the polymer electrolyte processing due to higher ac‐conductivity beneficial for the electrochemical device applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42489.  相似文献   

17.
Ti3C2Tx MXene has been reported to be a metallic two-dimensional (2D) material with high conductivity, whereas its photoluminescence (PL) mechanism is still under debate. Herein, we demonstrate that large Ti3C2Tx MXene flakes exhibit tunable PL under ambient conditions. The as-prepared Ti3C2Tx MXene flakes emit blue, yellow-green and red light under different excitation wavelengths. Their PL emission wavelengths redshift as the excitation wavelength changes from violet to red light. Surface modification of the MXenes can further tune the PL peak wavelength into the near infrared region. Using density function theory (DFT) calculations, this excitation wavelength-dependent PL can be correlated to TiO2 defects that exist on the surface of Ti3C2Tx. Our study expounds on the optical properties of Ti3C2Tx MXene and is helpful for comprehensively understanding this novel material.  相似文献   

18.
《Ceramics International》2022,48(7):9059-9066
Highly active two-dimensional (2D) nanocomposites have been widely concerned in the field of gas sensors because of their unique advantages and synergistic effects. 2D/2D SnO2 nanosheets/Ti3C2Tx MXene nanocomposites were synthesized by using layered Ti3C2Tx MXene and uniform SnO2 nanosheets by hydrothermal method. Characterization results show that the SnO2 nanosheets are well dispersed and vertically anchored on the layered Ti3C2Tx MXene surface, forming heterogeneous interfaces. Based on the gas-adsorption capabilities and synergistic effects of electronic properties, SnO2 nanosheets/Ti3C2Tx MXene nanocomposites show high triethylamine (TEA) gas-sensing performance at low temperature (140 °C). The sensor responses of the nanocomposites and pure SnO2 nanosheets to 50 ppm of TEA are 33.9 and 3.4, respectively. An enhancement mechanism for SnO2 nanosheets/Ti3C2Tx MXene nanocomposites is proposed for highly sensitive and selective detection of TEA at low temperature. The combination strategy of two-dimensional metal oxide semiconductor and multilayer MXene provides a new way for the development of cryogenic gas sensors in the future.  相似文献   

19.
The effect of five different metal oxides on the pyrolysis of poly(ethylene oxide) (PEO), polyacrylamide (PAM), and poly(vinyl alcohol) (PVA) was investigated using thermogravimetry. The presence of metal oxide did not influence the degradation of PEO while the order of metal oxide on the degradation rate of PAM and PVA was PbO > Co3O4 > CuO > ZnO > Al2O3. The miscibility and the decomposition of PEO–PAM and PVA–PAM blends were also investigated. The blends were found to be immiscible and the presence of one polymer did not influence the degradation of the other polymer in the polymer blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 233–240, 2006  相似文献   

20.
Tetracycline hydrochloride loaded poly(vinyl alcohol)/soybean protein isolate/zirconium (Tet–PVA/SPI/ZrO2) nanofibrous membranes were fabricated via an electrospinning technique. The average diameter of the PVA/soybean protein isolate (SPI)/ZrO2 nanofibers used as drug carriers increased with increasing ZrO2 content, and the nanofibers were uneven and tended to stick together when the ZrO2 content was above 15 wt %. The Tet–PVA/SPI/ZrO2 nanofibers were similar in morphology when the loading dosage of the model drug tetracycline hydrochloride was below 6 wt %. The PVA, SPI, and ZrO2 units were linked by hydrogen bonds in the hybrid networks, and the addition of ZrO2 improved the thermostability of the polymer matrix. The Tet–PVA/SPI/ZrO2 nanofibrous membranes exhibited good controlled drug‐release properties and antimicrobial activity against Staphylococcus aureus. The results of this study suggest that those nanofibrous membranes were suitable for drug delivery and wound dressing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40903.  相似文献   

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