Contact Angle Of Thin Film Research Articles

Facile fabrication of Au thin film substrates with crack-like nanogaps for surface-enhanced Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) has the advantage of nondestructive, quick, and accurate detection of harmful substances. Among the methods used to fabricate SERS substrates, a conventional evaporation equipment can achieve nanostructure of various shapes and sizes by adjusting the process pressure. In this study, general thermal evaporation equipment was utilized to fabricate SERS substrates. Au thin films with nanogaps were deposited on bare Si wafers with different process pressures and film thicknesses to vary the shape and size of the nanogaps. The microstructure was observed through scanning electron microscopy and transmission electron microscopy. In addition, the contact angle and reflectance of the Au thin films were measured. As the process pressure increased, the light reflectance decreased and the contact angle of the film increased. The SERS effect was found to be influenced by the width, depth, and number of nanogaps, reflectivity, and contact angle of the thin films. Optimal performance was observed under a process pressure of 13.3 Pa and film thickness of 215 nm. Under these conditions, the 2 µM rhodamine 6 G, allura red AC, and sunset yellow FCF were detected, and the uniformity and reproducibility of the thin film were also confirmed over a 6-inch substrate.

Chế tạo màng mỏng có tính kị nước và siêu kị nước dựa trên vật liệu octadecylamin bằng các phương pháp hóa – lý khác nhau

Thin films based on octadecylamine (ODA) material have been successfully fabricated by different methods: Langmuir-Blodgett (LB) method, spin-coating, spray-coating and dip-coating methods. The films obtained on the glass substrate were investigated for their optical properties (Uv-vis), film morphology (digital microscope, SEM) and contact angle. The solution and thin film absorption spectra of ODA and the mixtures of ODA and polymer RTV/SR do not absorb in the wavelength of the visible light region. The SEM analysis results show that the film morphology of ODA strongly depends on the nature of the ODA solution and the method of film formation and these are important factors affecting the different hydrophobicity of ODA films. Comparison of the droplet contact angle of thin films obtained by the above methods shows that the films fabricated by LB, spin-coating and spray-coating all increase the hydrophobicity of the glass substrate with the droplet contact angle range from 100o-145o, while dip-coating it is possible to fabricate superhydrophobic films with contact angles up to 161o.

Total Pressure and Annealing Temperature Effects on Structure and Photo-Induce Hydrophilicity of Reactive DC Sputtered TiO2 Thin Films

Nano-crystalline Titanium dioxide (TiO 2 ) has been well-known as a one of the most useful semiconductor material for application in self-cleaning coating which contains hydrophilic property. In this research, the films were deposited on un-heated silicon and glass slide substrates by home-made reactive unbalance magnetron sputtering system at various total gas pressures of 3.0x10 -3 , 5.0x10 -3 and 7.0x10 -3 mbar, as deposited thin films of 7.0x10 -3 mbar annealed in the ambient air at 100 o C, 300 o C and 500 o C, respectively. The effect of total pressure and annealing temperatures on structure, surface morphology and hydrophilic properties were characterized by X-ray Diffraction (XRD), Atomic Force Microscope (AFM) and contact angle meter under UV illumination. The results reveal that the crystal structure, surface morphology and photo-induce hydrophilicity were strongly influence by total pressure and annealing temperature. The films showed mixed phase of rutile and anatase. The phase transition from rutile to mixed phase of anatase/rutile was observed with increase total pressure. In addition, the roughness increased from 2.1 to 5.3 nm which give a greater hydrophicity. The enhancement of crystallinity and hydrophilic properties were obtained by varied the annealing temperature. The phase mixture of anatase/rutite and annealed temperature of 300 o C show that the contact angle of thin film became 0 o after UV light irradiation which exhibited clearly superhydrohilic property.

Effect of magnesium doping on the light-induced hydrophilicity of ZnO thin films

Undoped and Mg-doped ZnO thin films were deposited on Si (111) and quartz substrates by using the sol-gel method. Microstructure, surface topography and water contact angle of the thin films have been measured by X-ray diffraction (XRD), an atomic force microscope (AFM) and water contact angle apparatus, respectively. The XRD results show that all the thin films are polycrystalline with a hexagonal structure and have a preferred orientation along the c-axis perpendicular to the substrate. With the increase of Mg concentration, the RMS roughness increases from 2.14 to 9.56 nm and the contact angle of the un-irradiated thin films decreases from 89° to 82°. The wetting behavior of the resulting films can be reversibly switched from hydrophobic to hydrophilic, through alternation of UV illumination and dark storage. The light-induced efficiency of the thin films increases with the increase of Mg concentration.

Synthesis, characterization, and bulk properties of amphiphilic copolymers containing fluorinated methacrylates from sequential copper‐mediated radical polymerization

AbstractThe partly fluorinated monomers, 2,2,2‐trifluoroethyl methacrylate (3FM), 2,2,3,3,4,4,5,5‐octafluoropentyl methacrylate (8FM), and 1,1,2,2‐tetrahydroperfluorodecyl methacrylate (17FM) have been used in the preparation of block copolymers with methyl methacrylate (MMA), 2‐methoxyethyl acrylate (MEA), and poly(ethylene glycol) methyl ether methacrylate (PEGMA) by Atom Transfer Radical Polymerization. A kinetic study of the 3FM homopolymerization initiated with ethyl bromoisobutyrate and Cu(I)Br/N‐(n‐propyl)‐2‐pyridylmethanimine reveals a living/controlled polymerization in the range 80–110 °C, with apparent rate constants of 1.6 · 10−4 s−1 to 2.9 · 10−4 s−1. Various 3FM containing block copolymers with MMA are prepared by sequential monomer addition or from a PMMA macroinitiator in all cases with controlled characteristics. Block copolymers of 3FM and PEGMA resulted in block copolymers with PDI < 1.22, whereas block copolymers from 3FM and MEA have less controlled characteristics. The block copolymers based on MMA with 8FM and 17 FM have PDI's < 1.30. The glass transition temperatures of the block copolymers are dominated by the majority monomer, as the sequential monomer addition results in too short pure blocks to induce observable microphase separation. The thermal stability of the fluorinated poly((meth)acrylate)s in inert atmosphere is less than that of corresponding nonfluorinated poly((meth)acrylate)s. The presence of fluorinated blocks significantly increases the advancing water contact angle of thin films compared to films of the nonfluorinated poly((meth)acrylate)s. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8097–8111, 2008