Visible transparent yet low infrared-emissivity(ε)polymeric materials are highly anticipated in many applications,whereas the fabrication of which remains a formidable challenge.Herein,visible transparent,flexible,an...Visible transparent yet low infrared-emissivity(ε)polymeric materials are highly anticipated in many applications,whereas the fabrication of which remains a formidable challenge.Herein,visible transparent,flexible,and low-εpolymeric films were fabricated by nanocoating decoration of indium tin oxide(ITO)and MXene on polyethylene terephthalate(PET)film surface through magnetron sputtering and spray coating,respectively.The obtained PET-ITO@MXene(PET-IM)film exhibits lowεof 24.7%and high visible transmittance exceeding 50%,endowing it with excellent visible transparent infrared stealthy by reducing human skin radiation temperature from 32 to 20.8°C,and remarkable zero-energy passive radiative heating capability(5.7°C).Meanwhile,the transparent low-εPET-IM film has high solar absorptivity and electrical conductivity,enabling superior solar/electric to thermal conversion performance.Notably,the three heating modes of passive radiative and active solar/electric can be integrated together to cope with complex heating scenarios.These visible transparent low-εpolymeric films are highly promising in infrared stealth,building daylighting and thermal management,and personal precision heating.展开更多
Self-assembly post-modification has proven to be an efficient strategy to build higher-order supramolecular architectures and functional materials. In this study, we successfully realized the construction'of a new fa...Self-assembly post-modification has proven to be an efficient strategy to build higher-order supramolecular architectures and functional materials. In this study, we successfully realized the construction'of a new family of neutral supramolecular polymeric films containing well-defined metallacycles as the main scaffolds through combination Of coordination-driven self-assembly with post-electropolymerization. The obtained neutral polymeric materials were fully characterized by the cyclic voltammogram (CV), SEM, and TEM. The thickness of the films was able to be well regulated by the number of scanning cycles. Moreover, we found that the shape of the metallacycles and the number of triphenylamine moieties played important roles in the formation of the final polymer films. We believe that the introduction of the neutral metallacycles into the final polymer structures not only enriches the library of supramolecular polymeric films but also provides a new platform to study neutral molecule detection, separation, and capture.展开更多
The imprinted polymeric film was synthesized on the glass-carbon electrodes directly. The response to the template molecule-dopamine and other molecules with similar structure was measured by cyclic voltammetry. The r...The imprinted polymeric film was synthesized on the glass-carbon electrodes directly. The response to the template molecule-dopamine and other molecules with similar structure was measured by cyclic voltammetry. The response of dopamine on imprinted electrode was much higher than that of other molecules, because of the existing of micro-cavities in polymeric film fitting with the size and shape of dopamine in the imprinted polymer. Experimental results showed that dopamine can be enriched by the imprinted film, therefore increasing the sensitivity of the sensor. The imprinted film could also efface the interference of ascorbic acid, indicating that dopamine can be determined with a large excess of ascorbic acid.展开更多
An efficient interface modification is introduced to improve the performance of polymeric thin film transistors. This efficient interface modification is first achieved by 4-fluorothiophenol(4-FTP) self-assembled mo...An efficient interface modification is introduced to improve the performance of polymeric thin film transistors. This efficient interface modification is first achieved by 4-fluorothiophenol(4-FTP) self-assembled monolayers(SAM) to chemically treat the silver source–drain(S/D) contacts while the silicon oxide(SiO2) dielectric interface is further primed by either hexamethyldisilazane(HMDS) or octyltrichlorosilane(OTS-C8). Results show that contact resistance is the dominant factor that limits the field effect mobility of the PTDPPTFT4 transistors. With proper surface modification applied to both the dielectric surface and the bottom contacts, the field effect mobilities of the bottom-gate bottom-contact PTDPPTFT4 transistors were significantly improved from 0.15 cm^2·V^-1·s^-1 to 0.91 cm^2·V^-1·s^-1.展开更多
Lightweight,high-efficiency and low reflection electromagnetic interference(EMI)shielding polymer composites are greatly desired for addressing the challenge of ever-increasing electromagnetic pollution.Lightweight la...Lightweight,high-efficiency and low reflection electromagnetic interference(EMI)shielding polymer composites are greatly desired for addressing the challenge of ever-increasing electromagnetic pollution.Lightweight layered foam/film PVDF nanocomposites with efficient EMI shielding effectiveness and ultralow reflection power were fabricated by physical foaming.The unique layered foam/film structure was composed of PVDF/SiCnw/MXene(Ti_(3)C_(2)Tx)composite foam as absorption layer and highly conductive PVDF/MWCNT/GnPs composite film as a reflection layer.The foam layer with numerous heterogeneous interfaces developed between the SiC nanowires(SiCnw)and 2D MXene nanosheets imparted superior EM wave attenuation capability.Furthermore,the microcellular structure effectively tuned the impedance matching and prolonged the wave propagating path by internal scattering and multiple reflections.Meanwhile,the highly conductive PVDF/MWCNT/GnPs composite(~220 S m^(−1))exhibited superior reflectivity(R)of 0.95.The tailored structure in the layered foam/film PVDF nanocomposite exhibited an EMI SE of 32.6 dB and a low reflection bandwidth of 4 GHz(R<0.1)over the Kuband(12.4-18.0 GHz)at a thickness of 1.95 mm.A peak SER of 3.1×10^(-4) dB was obtained which corresponds to only 0.0022% reflection efficiency.In consequence,this study introduces a feasible approach to develop lightweight,high-efficiency EMI shielding materials with ultralow reflection for emerging applications.展开更多
The effects of working pressure on the component, surface morphology, surface roughness, and deposition rate of glow discharge polymer (GDP) films by a trans-2-butene/hydrogen gas mixture were investigated based on ...The effects of working pressure on the component, surface morphology, surface roughness, and deposition rate of glow discharge polymer (GDP) films by a trans-2-butene/hydrogen gas mixture were investigated based on plasma characteristics diagnosis. The composition and ion energy distributions of a multi-carbon (CaHs/H2) plasma mixture at different working pressures were diagnosed by an energy-resolved mass spectrometer (MS) during the GDP film deposition process. The Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (SEM) and white-fight interferometer (WLI) results were obtained to investigate the structure, morphology and roughness characterization of the deposited films, respectively. It was found that the degree of ionization of the C4H8/H2 plasma reduces with an increase in the working pressure. At a low working pressure, the C-H fragments exhibited small-mass and high ion energy in plasma. In this case, the film had a low CH3/CH2 ratio, and displayed a smooth surface without any holes, cracks or asperities. While the working pressure increased to 15 Pa, the largest number of large-mass fragments led to the deposition rate reaching a maximum of 2.11 #m h-1, and to hole defects on the film surface. However, continuing to increase the working pressure, the film surface became smooth again, and the interface between clusters became inconspicuous without etching pits.展开更多
Coarse-grained molecular dynamics simulations were carried out to investigate the dewetting behavior of a polymer thin film on partial wetting solid surface at the early stage of the dewetting process. Spontaneous dew...Coarse-grained molecular dynamics simulations were carried out to investigate the dewetting behavior of a polymer thin film on partial wetting solid surface at the early stage of the dewetting process. Spontaneous dewetting is initiated by removing a band of strip from both the ends of the liquid polymer film which has achieved equilibrium. The solid-liquid interaction and temperature were varied to show their influence on the dewetting dynamics during dewetting as well as the shape evolution of the liquid polymer film. As is consistent with the results obtained in previous researches, the liquid film recedes at a constant speed initially with different solid-liquid couplings and tempe- ratures. Furthermore, smaller coupling parameters or higher temperatures tend to accelerate the recession speed of the liquid film and shorten the constant-speed recession duration. Obvious rims were not always observed. Both coupling parameter and temperature can influence the emergence of the rims.展开更多
Polymer LB films containing photofuntional groups were prepared by the copolymerization of N-dodecylacrylamide (DDA), which has an excellent property to form a stable monolayer and LB multilayerswith photofunctional m...Polymer LB films containing photofuntional groups were prepared by the copolymerization of N-dodecylacrylamide (DDA), which has an excellent property to form a stable monolayer and LB multilayerswith photofunctional monomers. Tris(2, 2'-bipyridine) ruthenium complex, Ru(bpy)_3^(2+), one of the most well-known redox-active sensitizer, was incorporated into the DDA copolymer. The photogalvanic effect based onthe photoinduced electron transfer using the ruthenium complex in the polymer LB monolayer was discussed.展开更多
In order to perform data acquisition and avoid unwanted over-current damage to the power supply, a convenient and real-time method of experimentally investigating repetitive nanosecond-pulse breakdown in polymer diele...In order to perform data acquisition and avoid unwanted over-current damage to the power supply, a convenient and real-time method of experimentally investigating repetitive nanosecond-pulse breakdown in polymer dielectric samples is presented. The measurement-acquisition and control system not only records breakdown voltage and current, and time-to-breakdown duration, but also provides a real-time power-off protection for the power supply. Furthermore, the number of applied pulses can be calculated by the product of the time-to-breakdown duration and repetition rate. When the measured time-to-breakdown duration error is taken into account, the repetition rate of applied nanosecond-pulses should be below 40kHz. In addition, some experimental data on repetitive nanosecond-pulse breakdown of polymer films are presented and discussed.展开更多
The CO_2 quenching method has been used for the first time to determine the active complex concen- tration in Nd(naph)_3-Al(i-Bu)_3 catalyst system for polymerization of phenylacetylene into polyphenylacetylene(PPA)fi...The CO_2 quenching method has been used for the first time to determine the active complex concen- tration in Nd(naph)_3-Al(i-Bu)_3 catalyst system for polymerization of phenylacetylene into polyphenylacetylene(PPA)films.The kinetics and mechanism of this polymerization have been investigated by CO_2 quenching and IR,UV analytical methods.The kinetic equation can be expressed as Rp=k[M][Cp],and the apparent activation energy is about 13.6 kJ/mol.There is self-termination of chain propagating.Models for formation of the active complex and polymerization mechanism are proposed.展开更多
The optical properties of the pure polymer film and polymer films doped with Phenol Red dye at different concentrations were investigated. The films were prepared using the casting technique. Poly (methyl-methacrylate...The optical properties of the pure polymer film and polymer films doped with Phenol Red dye at different concentrations were investigated. The films were prepared using the casting technique. Poly (methyl-methacrylate) (PMMA) polymer was doped with the Phenol Red dye dissolved in a mixture of chloroform and little quantity of methanol, used as suitable solvent for both the dye and the polymer. The spectral absorption measurements of these films were carried out at different dye concentrations using UV-Vis double-beam spectrophotometer in the wavelength range 300 - 800 nm. The optical parameters of the prepared Phenol Red dye doped polymer films, absorption coefficient (α), extinction coefficient (κ), refractive index (n), optical and electrical conductivities (σ<sub>opt</sub> and σ<sub>elect</sub>), and optical energy band gap (E<sub>g</sub>), were determined. The results showed that the Phenol Red dye doped polymer film is a good candidate for photonic applications such as, solar cells, optical sensors, and other photonic devices.展开更多
Fulgide 1-E doped in polystyrene polymer films was heated at various annealing temperatures.Upon irradiation with UV light(366 nm),fulgide 1-E undergoes a conrotatory ring closure to the pink colored closed form 1-C.T...Fulgide 1-E doped in polystyrene polymer films was heated at various annealing temperatures.Upon irradiation with UV light(366 nm),fulgide 1-E undergoes a conrotatory ring closure to the pink colored closed form 1-C.The later color was switched back to the original color when the films were irradiated with white light.The kinetics of photocoloration and photobleaching processes were followed spectrophotometrically by monitoring the absorbance of the ring closed product 1-C at itsλ_(max) of 525 nm.The first-...展开更多
When colloidal silver particles were chemically deposited onto polymer film as an over-coating layer, surface-enhanced Raman scattering (SERS) spectra could be collected for the surface analysis. SERS measurements of ...When colloidal silver particles were chemically deposited onto polymer film as an over-coating layer, surface-enhanced Raman scattering (SERS) spectra could be collected for the surface analysis. SERS measurements of liquid crystal film were successfully performed without disturbing the surface morphology.展开更多
It has been a long-standing question whether dewetting of polymer film from non-wettable substrate surfaceswherein the bicontinuous morphology never forms in the dewetting film is due to spinodal instability or hetero...It has been a long-standing question whether dewetting of polymer film from non-wettable substrate surfaceswherein the bicontinuous morphology never forms in the dewetting film is due to spinodal instability or heterogeneousnucleation. In this experiment, we use a simple method to make the distinction through introduction of topographical defectsof the films by rubbing the sample surface with a rayon cloth. Spinodal dewetting is identified for those films that dewet by acharateristic wavevector, q, independent of the density of rubbing-induced defects. Heterogeneous nucleation, on the otherhand, is identified for those with q increasing with increasing density of defects. Our result shows that PS films on oxidecoated silicon with thickness less than ≈ 13 nm are dominated by spinodal dewetting, but the thicker films are dominated bynucleation dewetting. We also confirm that spinodal dewetting does not necessarily lead to a bicontinuous morphology in thedewetting film, contrary to the classic theory of Cahn.展开更多
The thermal induced topography change in a model system consisting of a polymer film on a Si substrate capped by a thin metal layer has been studied by using AFM. Regular lateral patterns over large areas were observ...The thermal induced topography change in a model system consisting of a polymer film on a Si substrate capped by a thin metal layer has been studied by using AFM. Regular lateral patterns over large areas were observed on the surface when the system was heated to a sufficiently high temperature. 2D-FFT analysis to the AFM images indicates that the patterns are isotropic and have well defined periodicities. The periodicities of the characteristic patterns are found to depend strongly on the annealing temperature. The study of the kinetics of the formation reveals that such a topography forms almost instantaneously once the critical temperature is reached. It is suggested that this wave-like surface morphology is driven by the thermal expansion coefficient mismatch of the different layers. This method for generating regular wave-like patterns could be used as a general method for patterning various organic materials into micro/nanostructures.展开更多
Polymer thin film deposition using an atmospheric pressure micro-plasma jet driven by dual-frequency excitations is described in this paper. The discharge process was operated with a mixture of argon (6 slm) and a s...Polymer thin film deposition using an atmospheric pressure micro-plasma jet driven by dual-frequency excitations is described in this paper. The discharge process was operated with a mixture of argon (6 slm) and a small amount of acetone (0-2100 ppm). Plasma composition was measured by optical emission spectroscopy (OES). In addition to a large number of Ar spectra lines, we observed some spectra of C, CN, CH and C2. Through changing acetone content mixed in argon, we found that the optimum discharge condition for deposition can be characterized by the maximum concentration of carbonaceous species. The deposited film was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The XPS indicated that the film was mostly composed of C with trace amount of O and N elements. The FTIR suggested different carbon-containing bonds (-CHx, C=O, C=C, C-O-C) presented in the deposited film.展开更多
We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly(3-hex...We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly(3-hexylthiophene) P3HT:[6-6] phenyl-(6) butyric acid methyl ester(PCBM). 1% vanadium-doped TiO2nanoparticles were synthesized via the solvothermal method. Crystalline structure, morphology, and optical properties of pure and vanadium-doped TiO2 thin films were studied by different techniques such as x-ray diffraction, scanning electron microscopy, transmittance electron microscopy, and UV–visible transmission spectrum. The doctor blade method which is compatible with roll-2-roll printing was used for deposition of pure and vanadium-doped TiO2 thin films with thicknesses of 30 nm and 60 nm. The final results revealed that the best thickness of TiO2 thin films for our fabricated cells was 30 nm. The cell with vanadium-doped TiO2 thin film showed slightly higher power conversion efficiency and great Jsc of 10.7 mA/cm^2 compared with its pure counterpart. In the cells using 60 nm pure and vanadium-doped TiO2 layers, the cell using the doped layer showed much higher efficiency. It is remarkable that the external quantum efficiency of vanadium-doped TiO2 thin film was better in all wavelengths.展开更多
Dielectric polymer films are energy storage materials that are used in pulse power operations, power electronics and sustainable energy applications. This paper reviews energy storage devices with focus on dielectric ...Dielectric polymer films are energy storage materials that are used in pulse power operations, power electronics and sustainable energy applications. This paper reviews energy storage devices with focus on dielectric film capacitors. Two prominent examples of polymer dielectrics Polyetherimide (PEI) and Poly (tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) (THV) have been discussed. Polyetherimide (PEI) is an amorphous polymer recognized for its high-temperature capability, low dielectric loss and high dielectric strength. THV is a semi-crystalline polymer with high dielectric constant, high-temperature capability and charge-discharge efficiency. The primary focus of this paper is to introduce the reader to the fabrication procedures and characterization techniques used in research labs for processing of dielectric polymers. The fabrication and characterization process of both polymers has been discussed in detail to shed the light on experimental process in this area of research.展开更多
By means of changing the detection angle, the molecular conformation of a new type of polymer surfactant, acrylamide-poly(oxyethykene alkyl ether)acrylate-anionic monomer random copolymer, was studied by x-ray photoel...By means of changing the detection angle, the molecular conformation of a new type of polymer surfactant, acrylamide-poly(oxyethykene alkyl ether)acrylate-anionic monomer random copolymer, was studied by x-ray photoelectron spectroscopy(XPS) in detail.展开更多
基金Financial support of the National Natural Science Foundation of China(No.52003248)the China Postdoctoral Science Foundation(Nos.2018M642780 and 2021T140613)+1 种基金the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University)(No.sklpme2019-4-31)the Key Research and Development and Promotion projects of Henan Province(No.202102210032)are gratefully acknowledged.
文摘Visible transparent yet low infrared-emissivity(ε)polymeric materials are highly anticipated in many applications,whereas the fabrication of which remains a formidable challenge.Herein,visible transparent,flexible,and low-εpolymeric films were fabricated by nanocoating decoration of indium tin oxide(ITO)and MXene on polyethylene terephthalate(PET)film surface through magnetron sputtering and spray coating,respectively.The obtained PET-ITO@MXene(PET-IM)film exhibits lowεof 24.7%and high visible transmittance exceeding 50%,endowing it with excellent visible transparent infrared stealthy by reducing human skin radiation temperature from 32 to 20.8°C,and remarkable zero-energy passive radiative heating capability(5.7°C).Meanwhile,the transparent low-εPET-IM film has high solar absorptivity and electrical conductivity,enabling superior solar/electric to thermal conversion performance.Notably,the three heating modes of passive radiative and active solar/electric can be integrated together to cope with complex heating scenarios.These visible transparent low-εpolymeric films are highly promising in infrared stealth,building daylighting and thermal management,and personal precision heating.
文摘Self-assembly post-modification has proven to be an efficient strategy to build higher-order supramolecular architectures and functional materials. In this study, we successfully realized the construction'of a new family of neutral supramolecular polymeric films containing well-defined metallacycles as the main scaffolds through combination Of coordination-driven self-assembly with post-electropolymerization. The obtained neutral polymeric materials were fully characterized by the cyclic voltammogram (CV), SEM, and TEM. The thickness of the films was able to be well regulated by the number of scanning cycles. Moreover, we found that the shape of the metallacycles and the number of triphenylamine moieties played important roles in the formation of the final polymer films. We believe that the introduction of the neutral metallacycles into the final polymer structures not only enriches the library of supramolecular polymeric films but also provides a new platform to study neutral molecule detection, separation, and capture.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 0 175 0 0 9) ,theDoctoralFoundationofEducationMinistryofChina (No .2 0 0 2 0 0 5 5 0 0 2 )andtheNaturalScienceFoundationofTianjin (No .0 3 3 60 3 5 11)
文摘The imprinted polymeric film was synthesized on the glass-carbon electrodes directly. The response to the template molecule-dopamine and other molecules with similar structure was measured by cyclic voltammetry. The response of dopamine on imprinted electrode was much higher than that of other molecules, because of the existing of micro-cavities in polymeric film fitting with the size and shape of dopamine in the imprinted polymer. Experimental results showed that dopamine can be enriched by the imprinted film, therefore increasing the sensitivity of the sensor. The imprinted film could also efface the interference of ascorbic acid, indicating that dopamine can be determined with a large excess of ascorbic acid.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB328803)
文摘An efficient interface modification is introduced to improve the performance of polymeric thin film transistors. This efficient interface modification is first achieved by 4-fluorothiophenol(4-FTP) self-assembled monolayers(SAM) to chemically treat the silver source–drain(S/D) contacts while the silicon oxide(SiO2) dielectric interface is further primed by either hexamethyldisilazane(HMDS) or octyltrichlorosilane(OTS-C8). Results show that contact resistance is the dominant factor that limits the field effect mobility of the PTDPPTFT4 transistors. With proper surface modification applied to both the dielectric surface and the bottom contacts, the field effect mobilities of the bottom-gate bottom-contact PTDPPTFT4 transistors were significantly improved from 0.15 cm^2·V^-1·s^-1 to 0.91 cm^2·V^-1·s^-1.
基金the financial support of NSERC(Discovery Grant RGPIN-2015-03985).
文摘Lightweight,high-efficiency and low reflection electromagnetic interference(EMI)shielding polymer composites are greatly desired for addressing the challenge of ever-increasing electromagnetic pollution.Lightweight layered foam/film PVDF nanocomposites with efficient EMI shielding effectiveness and ultralow reflection power were fabricated by physical foaming.The unique layered foam/film structure was composed of PVDF/SiCnw/MXene(Ti_(3)C_(2)Tx)composite foam as absorption layer and highly conductive PVDF/MWCNT/GnPs composite film as a reflection layer.The foam layer with numerous heterogeneous interfaces developed between the SiC nanowires(SiCnw)and 2D MXene nanosheets imparted superior EM wave attenuation capability.Furthermore,the microcellular structure effectively tuned the impedance matching and prolonged the wave propagating path by internal scattering and multiple reflections.Meanwhile,the highly conductive PVDF/MWCNT/GnPs composite(~220 S m^(−1))exhibited superior reflectivity(R)of 0.95.The tailored structure in the layered foam/film PVDF nanocomposite exhibited an EMI SE of 32.6 dB and a low reflection bandwidth of 4 GHz(R<0.1)over the Kuband(12.4-18.0 GHz)at a thickness of 1.95 mm.A peak SER of 3.1×10^(-4) dB was obtained which corresponds to only 0.0022% reflection efficiency.In consequence,this study introduces a feasible approach to develop lightweight,high-efficiency EMI shielding materials with ultralow reflection for emerging applications.
基金financially supported by National Natural Science Foundation of China (No. 51401194)
文摘The effects of working pressure on the component, surface morphology, surface roughness, and deposition rate of glow discharge polymer (GDP) films by a trans-2-butene/hydrogen gas mixture were investigated based on plasma characteristics diagnosis. The composition and ion energy distributions of a multi-carbon (CaHs/H2) plasma mixture at different working pressures were diagnosed by an energy-resolved mass spectrometer (MS) during the GDP film deposition process. The Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (SEM) and white-fight interferometer (WLI) results were obtained to investigate the structure, morphology and roughness characterization of the deposited films, respectively. It was found that the degree of ionization of the C4H8/H2 plasma reduces with an increase in the working pressure. At a low working pressure, the C-H fragments exhibited small-mass and high ion energy in plasma. In this case, the film had a low CH3/CH2 ratio, and displayed a smooth surface without any holes, cracks or asperities. While the working pressure increased to 15 Pa, the largest number of large-mass fragments led to the deposition rate reaching a maximum of 2.11 #m h-1, and to hole defects on the film surface. However, continuing to increase the working pressure, the film surface became smooth again, and the interface between clusters became inconspicuous without etching pits.
基金Supported by the National Natural Science Foundation of China(Nos.20774036 50930001+1 种基金 20933001)the Program for New Century Excellent Talents in University of China and Fok Ying Tung Education Foundation(No.114018)
文摘Coarse-grained molecular dynamics simulations were carried out to investigate the dewetting behavior of a polymer thin film on partial wetting solid surface at the early stage of the dewetting process. Spontaneous dewetting is initiated by removing a band of strip from both the ends of the liquid polymer film which has achieved equilibrium. The solid-liquid interaction and temperature were varied to show their influence on the dewetting dynamics during dewetting as well as the shape evolution of the liquid polymer film. As is consistent with the results obtained in previous researches, the liquid film recedes at a constant speed initially with different solid-liquid couplings and tempe- ratures. Furthermore, smaller coupling parameters or higher temperatures tend to accelerate the recession speed of the liquid film and shorten the constant-speed recession duration. Obvious rims were not always observed. Both coupling parameter and temperature can influence the emergence of the rims.
文摘Polymer LB films containing photofuntional groups were prepared by the copolymerization of N-dodecylacrylamide (DDA), which has an excellent property to form a stable monolayer and LB multilayerswith photofunctional monomers. Tris(2, 2'-bipyridine) ruthenium complex, Ru(bpy)_3^(2+), one of the most well-known redox-active sensitizer, was incorporated into the DDA copolymer. The photogalvanic effect based onthe photoinduced electron transfer using the ruthenium complex in the polymer LB monolayer was discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 50707032 and 50437020)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KGCX2-YW-339)the State Key Laboratory of Controland Simulation of Power System and Generation Equipment in Tsinghua University (Grant No. SKLD09KZ05)
文摘In order to perform data acquisition and avoid unwanted over-current damage to the power supply, a convenient and real-time method of experimentally investigating repetitive nanosecond-pulse breakdown in polymer dielectric samples is presented. The measurement-acquisition and control system not only records breakdown voltage and current, and time-to-breakdown duration, but also provides a real-time power-off protection for the power supply. Furthermore, the number of applied pulses can be calculated by the product of the time-to-breakdown duration and repetition rate. When the measured time-to-breakdown duration error is taken into account, the repetition rate of applied nanosecond-pulses should be below 40kHz. In addition, some experimental data on repetitive nanosecond-pulse breakdown of polymer films are presented and discussed.
文摘The CO_2 quenching method has been used for the first time to determine the active complex concen- tration in Nd(naph)_3-Al(i-Bu)_3 catalyst system for polymerization of phenylacetylene into polyphenylacetylene(PPA)films.The kinetics and mechanism of this polymerization have been investigated by CO_2 quenching and IR,UV analytical methods.The kinetic equation can be expressed as Rp=k[M][Cp],and the apparent activation energy is about 13.6 kJ/mol.There is self-termination of chain propagating.Models for formation of the active complex and polymerization mechanism are proposed.
文摘The optical properties of the pure polymer film and polymer films doped with Phenol Red dye at different concentrations were investigated. The films were prepared using the casting technique. Poly (methyl-methacrylate) (PMMA) polymer was doped with the Phenol Red dye dissolved in a mixture of chloroform and little quantity of methanol, used as suitable solvent for both the dye and the polymer. The spectral absorption measurements of these films were carried out at different dye concentrations using UV-Vis double-beam spectrophotometer in the wavelength range 300 - 800 nm. The optical parameters of the prepared Phenol Red dye doped polymer films, absorption coefficient (α), extinction coefficient (κ), refractive index (n), optical and electrical conductivities (σ<sub>opt</sub> and σ<sub>elect</sub>), and optical energy band gap (E<sub>g</sub>), were determined. The results showed that the Phenol Red dye doped polymer film is a good candidate for photonic applications such as, solar cells, optical sensors, and other photonic devices.
文摘Fulgide 1-E doped in polystyrene polymer films was heated at various annealing temperatures.Upon irradiation with UV light(366 nm),fulgide 1-E undergoes a conrotatory ring closure to the pink colored closed form 1-C.The later color was switched back to the original color when the films were irradiated with white light.The kinetics of photocoloration and photobleaching processes were followed spectrophotometrically by monitoring the absorbance of the ring closed product 1-C at itsλ_(max) of 525 nm.The first-...
基金support by the Visiting Scholar Foundation of the Key Lab in Nankai University, and to financial support by the National Natural Science Foundation of China (No. 29974014).
文摘When colloidal silver particles were chemically deposited onto polymer film as an over-coating layer, surface-enhanced Raman scattering (SERS) spectra could be collected for the surface analysis. SERS measurements of liquid crystal film were successfully performed without disturbing the surface morphology.
基金This work was supported by the Institute of Nano Science and Technology and the Hong Kong University of Science and Technology through the Postdoctoral Matching Fund.
文摘It has been a long-standing question whether dewetting of polymer film from non-wettable substrate surfaceswherein the bicontinuous morphology never forms in the dewetting film is due to spinodal instability or heterogeneousnucleation. In this experiment, we use a simple method to make the distinction through introduction of topographical defectsof the films by rubbing the sample surface with a rayon cloth. Spinodal dewetting is identified for those films that dewet by acharateristic wavevector, q, independent of the density of rubbing-induced defects. Heterogeneous nucleation, on the otherhand, is identified for those with q increasing with increasing density of defects. Our result shows that PS films on oxidecoated silicon with thickness less than ≈ 13 nm are dominated by spinodal dewetting, but the thicker films are dominated bynucleation dewetting. We also confirm that spinodal dewetting does not necessarily lead to a bicontinuous morphology in thedewetting film, contrary to the classic theory of Cahn.
文摘The thermal induced topography change in a model system consisting of a polymer film on a Si substrate capped by a thin metal layer has been studied by using AFM. Regular lateral patterns over large areas were observed on the surface when the system was heated to a sufficiently high temperature. 2D-FFT analysis to the AFM images indicates that the patterns are isotropic and have well defined periodicities. The periodicities of the characteristic patterns are found to depend strongly on the annealing temperature. The study of the kinetics of the formation reveals that such a topography forms almost instantaneously once the critical temperature is reached. It is suggested that this wave-like surface morphology is driven by the thermal expansion coefficient mismatch of the different layers. This method for generating regular wave-like patterns could be used as a general method for patterning various organic materials into micro/nanostructures.
基金supported by National Natural Science Foundation of China(No.11165012)China Postdoctoral Science Foundation Funded Project(2011M501494+2 种基金2012T50831)Project of Key Laboratory of Atomic and Molecular Physics&Functional Materials of Gansu ProvinceProject of Northwest Normal University(NWNU-LKQN-11-9)
文摘Polymer thin film deposition using an atmospheric pressure micro-plasma jet driven by dual-frequency excitations is described in this paper. The discharge process was operated with a mixture of argon (6 slm) and a small amount of acetone (0-2100 ppm). Plasma composition was measured by optical emission spectroscopy (OES). In addition to a large number of Ar spectra lines, we observed some spectra of C, CN, CH and C2. Through changing acetone content mixed in argon, we found that the optimum discharge condition for deposition can be characterized by the maximum concentration of carbonaceous species. The deposited film was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The XPS indicated that the film was mostly composed of C with trace amount of O and N elements. The FTIR suggested different carbon-containing bonds (-CHx, C=O, C=C, C-O-C) presented in the deposited film.
文摘We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly(3-hexylthiophene) P3HT:[6-6] phenyl-(6) butyric acid methyl ester(PCBM). 1% vanadium-doped TiO2nanoparticles were synthesized via the solvothermal method. Crystalline structure, morphology, and optical properties of pure and vanadium-doped TiO2 thin films were studied by different techniques such as x-ray diffraction, scanning electron microscopy, transmittance electron microscopy, and UV–visible transmission spectrum. The doctor blade method which is compatible with roll-2-roll printing was used for deposition of pure and vanadium-doped TiO2 thin films with thicknesses of 30 nm and 60 nm. The final results revealed that the best thickness of TiO2 thin films for our fabricated cells was 30 nm. The cell with vanadium-doped TiO2 thin film showed slightly higher power conversion efficiency and great Jsc of 10.7 mA/cm^2 compared with its pure counterpart. In the cells using 60 nm pure and vanadium-doped TiO2 layers, the cell using the doped layer showed much higher efficiency. It is remarkable that the external quantum efficiency of vanadium-doped TiO2 thin film was better in all wavelengths.
文摘Dielectric polymer films are energy storage materials that are used in pulse power operations, power electronics and sustainable energy applications. This paper reviews energy storage devices with focus on dielectric film capacitors. Two prominent examples of polymer dielectrics Polyetherimide (PEI) and Poly (tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) (THV) have been discussed. Polyetherimide (PEI) is an amorphous polymer recognized for its high-temperature capability, low dielectric loss and high dielectric strength. THV is a semi-crystalline polymer with high dielectric constant, high-temperature capability and charge-discharge efficiency. The primary focus of this paper is to introduce the reader to the fabrication procedures and characterization techniques used in research labs for processing of dielectric polymers. The fabrication and characterization process of both polymers has been discussed in detail to shed the light on experimental process in this area of research.
文摘By means of changing the detection angle, the molecular conformation of a new type of polymer surfactant, acrylamide-poly(oxyethykene alkyl ether)acrylate-anionic monomer random copolymer, was studied by x-ray photoelectron spectroscopy(XPS) in detail.