无机合成化学作业

无机合成化学作业(2)付悦玮化新1101 41107261Title:Water Vapor Transfer Property through Fiber Assemblies with Compression Journal:Proceedings of Textile Bioengineering and Informatics Symposium 2010 Pages:1007-1011Abstract:Water vapor transfer property of fiber assemblies was studied using a newlydeveloped testing apparatus. An air pump and water bottle is used as the water vapor source for the upper chamber. Water vapor penetrates through the sample chamber to the lower chamber. Mass Diffusion constant is got by comparing the theoretical and experimental moisture concentration of the lower chamber. The method is proved to be efficient. We used the tester to study the influence of fiber assembly density on the property, owing to compression. Furthermore the influence of fiber arrangement was discussed as well. The study provides a way to select the optimum structure of fiber assemblies with the best water vapor transfer ability.Experienment:The measuring device, consisted of an aquarium air pump which wasblowing towards the liquid in the water vessel with a certain velocity so that water evaporated producing water vapor and was supplied to the upper measuring chamber through a pipe 6. The upper chamber is open to the atmosphere,so the pressure of it is kept coefficient during the testing process. Water vapor penetrated the fiber mass in fiber mass chamber 2. Two moisture sensors were separately placed at the bottom of the upper chamber and the top of the lower chamber. The signals generated from humidity sensors were fed into a recorder where they were processed and time-humidity curves were generated.The fiber assemblies in the chamber werecompressed from 0.0071 g/cm3to 0.035 g/cm3. After being tested, the material was put out of the chamberand the new material of the same density was tested instead and the test was repeated three times at a given density. The average value was used. Testing of all densities was of the same process. The device was housed in a chamber with the temperature of 28.0±0.5 °C and humidity of 65±5 % .Water vapor diffusion resistance is always used to evaluate water vapor transfer ability of fiber assemblies.We can get the parameter from the following model. As shown in Figure 2, constant humidity is fixed in the upper chamber and room humidity is maintained in thelower chamber initially. Moisture transferred form the upper chamber to the lower chamber because of humidity gradient.Title:Improved transfer ofchemical-vapor-deposited graphene through modification ofintermolecular interactions and solubility of poly(methylmethacrylate) layersJournal:CarbonPages:612-618Abstract:Clean chemical vapor deposition (CVD)-grown graphene surfaces with intrinsicelectrical properties were obtained by a modified poly(methylmethacrylate) (PMMA) transfer method. The modified method entails UV irradiation, followed by wet cleaning of the UV-irradiated PMMA layer using a mixture of isopropyl alcohol (IPA), acetone, and methyl isobutyl ketone(MIBK). The chemical structure of the PMMA layer degrades following UV irradiation under atmospheric conditions, via side-chain cleavage of the ester groups, resulting in reduced intermolecular interactions between the PMMA layer and the underlying graphene film. Furthermore, the IPA/MIBK/acetone mixture is shown to be a powerful solvent that can effectively remove the PMMA layer without leaving any PMMA residue, which could act as a source of cracks and scattering centers for charge carrier transport, on the graphene surface. Graphene transistors fabricated by this modified transfer method show high electron and hole mobilities with ideal threshold voltages of near 0 V.Experiment:1. Graphene growth and transfer Fig. 1a shows a schematic illustration of the modified PMMA transfer method for the fabrication of a clean graphene film. Monolayer graphene was grown by low-pressure CVD of methane (99.96%) on a 100-lm-thick 3 · 5 cm polycrystalline copper foil. Prior to growth, the copper foil was cleaned with acetone and IPA to remove surface contaminants. The copper foil was then immediately transferred into the CVD chamber and heated to the growth temperature of 1050 C under flowing hydrogen and argon. Methane (18 sccm)mixed with argon(1000 sccm) and hydrogen (90 sccm) was fed into the chamber, which was then held at 1050 C for 30 min. The sample was then rapidly cooled to room temperature under a flow of argon. Next, the as-grown graphene film was transferred to the target substrate by a modified PMMA transfer method. A 50-nm-thick PMMA layer with a molecular weight of 15,000 was spin-coated onto the surface of the graphene/copper substrate and cured at 180 C for 3min. The PMMA layer was then irradiated for 30 min with 256 nm UV radiation at room temperature, in air, using a 15W high-pressure mercury lamp positioned 3 cm from the sample. A sacrificial second PMMA layer with the thickness of 200 nm was then spin-coated onto the irradiated PMMA layer and cured at 180 C for 3min. The underlying copper foil was etched away by immersing the multilayer sample in a 0.2 M ammonium persulfate solution for 3 h. The resulting PMMA/graphene film was transferred to an arbitrary substrate, rinsed with deionized water, and dried. Finally, the PMMA layer was removed using a mixture of IPA, acetone, and MIBK (volume ratio of 1:1:1) for 6 h. Conventional PMMA transfer (without UV irradiation or PMMA removal) was also conducted for comparison. A 200-nm-thick PMMA layer with a molecular weight of 950,000 was spincoatedonto the surface of the graphene/copper substrate and cured at 180 C for 3 min. After copper etching and transfer, the PMMA layer was removed by dipping in an acetone for 6 h.2. CharacterizationThe surface morphologies of the graphene films were imaged by optical microscopy (OM, Nikon Eclipse LV100), atomic force microscopy (AFM, Park Systems XE-100 Multimodes), and transmission electron microscopy (TEM, FEI TECNAI G2 F20) with an acceleration voltage of 120 kV. Photolytic degradation of the molecular structure of the PMMA layer by UV irradiation was investigated by X-ray photoelectron spectroscopy (XPS, Thermo VG Scientific Inc. Multilab2000), using monochromatic Al Ka X-ray radiation, and Fourier transform infrared spectroscopy (FTIR, JASCO Model 4200UP). Crystallinity and impurity content of the graphene films were examined by confocal Raman spectrometry (NT-MDT, NTEGRA SPECTRA), using 532.8 and 632.8 nm excitation radiations and a Rayleigh line injection filter with a spectral range of 100–3600 cm 1 to account for the Stokes shift. Electrical transport characterization was performed by depositing a graphene FET at 10 3 Torr on a heavily doped Si substrate, a commonly used gate electrode. A thermally grown 300-nm-thick SiO2 layer served as the gate dielectric. Source and drain electrodeswere prepared by thermal evaporation of gold to a thickness of 100 nm. The electrode pattern was obtained using a conventional photolithography process. The channel length and width were 6 and 2 lm, respectively.。