Surface modification of textured silicon and its wetting behaviour

Textured silicon (Si) substrate were prepared using various texturing methods both chemical and physical and their water contact angle, surface topography and Raman spectra were studied and investigated. The effect of plasma and chemical treatment on micro/nanostructure and roughness of the surface with and without deposition of Octadecyltrichlorosilane (ODTS, Cl3Si (CH3)(17)), self-assembled monolayer (SAM) is investigated for achieving higher water contact angle (theta(c)). The importance of synergism of texturing with deposition of ODTS SAM in preparing superhydrophobic silicon surfaces has been discussed. It is shown that superhydrophobic silicon surfaces can be achieved on silicon surfaces by coating with ODTS, irrespective of whether it is textured or not, polished or unpolished, provided a chemical treatment is given to the surface prior to the ODTS coating.

Enhancing the mechanical and biological performance of a metallic biomaterial for orthopedic applications through changes in the surface oxide layer by nanocrystalline surface modification

Nanostructured metals are a promising class of biomaterials for application in orthopedics to improve the mechanical performance and biological response for increasing the life of biomedical implants. Surface mechanical attrition treatment (SMAT) is an efficient way of engineering nanocrystalline surfaces on metal substrates. In this work, 316L stainless steel (SS), a widely used orthopedic biomaterial, was subjected to SMAT to generate a nanocrystalline surface. Surface nanocrystallization modified the nature of the oxide layer present on the surface. It increased the corrosion-fatigue strength in saline by 50%. This increase in strength is attributed to a thicker oxide layer, residual compressive stresses, high strength of the surface layer, and lower propensity for intergranular corrosion in the nanocrystalline layer. Nanocrystallization also enhanced osteoblast attachment and proliferation. Intriguingly, wettability and surface roughness, the key parameters widely acknowledged for controlling the cellular response remained unchanged after nanocrystallization. The observed cellular behavior is explained in terms of the changes in electronic properties of the semiconducting passive oxide film present on the surface of 316L SS. Nanocrystallization increased the charge carrier density of the n-type oxide film likely preventing denaturation of the adsorbed cell-adhesive proteins such as fibronectin. In addition, a net positive charge developed on the otherwise neutral oxide layer, which is known to facilitate cellular adhesion. The role of changes in the electronic properties of the oxide films on metal substrates is thus highlighted in this work. This study demonstrates the advantages of nanocrystalline surface modification by SMAT for processing metallic biomaterials used in orthopedic implants.

Surface modification of titania aerogel films by oxygen plasma treatment for enhanced dye adsorption

Titania aerogels were synthesized by sol-gel route followed by ambient pressure subcritical drying technique. The aerogels synthesized in the present work possess a maximum surface area of 252 m(2)/g. The pore size distribution is between 2 and 30 nm which confirms their mesoporosity. The oxygen plasma treatment on titania aerogel thin films improved the surface area up to 273 m(2)/g and produced additional hydrophilic groups on the surface. It is confirmed by BET surface area, XPS and thermal analysis in conjunction with dye adsorption studies. After plasma treatment the dye adsorption capacity was increased 2.5 times higher than that of untreated aerogel film. The increased surface area and the hydrophilic groups generated on the titania aerogel surface during plasma treatment are responsible for enhanced dye adsorption. The overall nanoporous morphology of titania aerogel is preserved after plasma treatment. (C) 2015 Elsevier B.V. All rights reserved.

Surface modification of mild steel by a self-assembled cetyl-trimethyl ammonium bromide (CTAB) monolayer: Evaluation of its corrosion protection property

The surface of mild steel was modified by generating cetyl-trimethyl ammonium bromide (CTAB) self-assembled monolayer (SAM) to enhance the corrosion resistance property. The experimental parameters (pH and time) for SAM generation were optimized. The modified surface was characterized by infrared reflection absorption spectroscopy (IRRAS) and contact angle measurements. The SAM generated in 1 mM solution of CTAB at pH 2.5 for 2 h showed a regimented monolayer. Polarization and electrochemical impedance spectroscopic (EIS) studies demonstrated a significant enhancement in the corrosion resistance property of the SAM protected steel in both 1 M HCl and 3.5% NaCl solution. The CTAB SAM surface substantially reduced the corrosion rate by approximately 4 times in 1 M HCl and 1.5 times in 3.5% NaCl media as compared to bare steel. Scanning electron microscopy images confirmed the formation of lesser amounts of corrosion products on the SAM protected surface. (C) 2015 Elsevier B.V. All rights reserved.

Improving Nucleation in the Fabrication of High-Quality 3D Macro-Porous Copper Film through The Surface-Modification of A Polystyrene Colloid-Assembled Template

A new approach is developed to the fabrication of high-quality three-dimensional macro-porous copper films. A highly-ordered macroporous copper film is successfully produced on a polystyrene sphere (PS) template that has been modified by sodium dodecyl sulfate (SDS). It is shown that this procedure can change a hydrophobic surface of PS template into a hydrophilic surface. The present study is devoted to the influence of the electrolyte solution transport on the nucleation process. It is demonstrated that the permeability of the electrolyte solution in the nanochannels of the PS template plays an important role in the chemical electrodeposition of high-quality macroporous copper film. The permeability is drastically enhanced in our experiment through the surface modi. cation of the PS templates. The method could be used to homogeneously produce a large number of nucleations on a substrate, which is a key factor for the fabrication of the high-quality macroporous copper film.

Silicon Surface Modification with a Mixed Silanes Layer to Immobilize Proteins for Biosensor with Imaging Ellipsometry

One kind of surface modification method on silicon wafer was presented in this paper. A mixed silanes layer was used to modify silicon surface and rendered the surface medium hydrophobic. The mixed silanes layer contained two kinds of compounds, aminopropyltriethoxysilane (APTES) and methyltriethoxysilane (NITES). A few of APTES molecules in the layer was used to immobilize covalently human immunoglobulin G (IgG) on the silicon surface. The human IgG molecules immobilized covalently on the modified surface could retain their structures well and bind more antibody molecules than that on silicon surface modified with only APTES. This kind of surface modification method effectively improved the sensitivity of the biosensor with imaging ellipsometry.

High-power laser beam shaping by inseparable two-dimensional binary-phase gratings for surface modification of stamping dies

For surface modification of stamping dies, an inseparable two-dimensional binary-phase gratings is introduced to implement the wavefront transformation of high-power laser beams. The design and fabrication of the gratings are described in detail. Two-dimensional even sampling encoding scheme is adopted to overcome the limitations of conventional Dammann grating in the design of two-dimensional output patterns. High diffractive efficiency (>70%) can be achieved through the transformation of the Gaussian laser beam into several kinds of two-dimensional arrays in focal plan. The application of the binary-phase gratings in the laser surface modification of ductile iron is investigated, and the results show that the hardness and the wear resistance of the sample surface were improved significantly by using the binary-phase gratings. (C) 2008 Elsevier Ltd. All rights reserved.

Path Planner for Intelligent Laser Surface Modification

An optimal algorithm of manufacturing path planner for intelligent laser surface modification is presented. Elements included in the optimal objective have been analyzed. A 6-D manufacture trace that satisfies the requirements of special craft and 5-axis laser processing robot system has been generated from the path planner by method of parallel section in which combinations of modification spots size with curvature of processing surfaces and modification craft parameters are considered. Related experiments have been successfully carried out with the computer integrated multifunctional laser manufacturing system.

Chemical surface modification of poly-ε-caprolactone improves Schwann cell proliferation for peripheral nerve repair.

Poly-ε-caprolactone (PCL) is a biodegradable and biocompatible polymer used in tissue engineering for various clinical applications. Schwann cells (SCs) play an important role in nerve regeneration and repair. SCs attach and proliferate on PCL films but cellular responses are weak due to the hydrophobicity and neutrality of PCL. In this study, PCL films were hydrolysed and aminolysed to modify the surface with different functional groups and improve hydrophilicity. Hydrolysed films showed a significant increase in hydrophilicity while maintaining surface topography. A significant decrease in mechanical properties was also observed in the case of aminolysis. In vitro tests with Schwann cells (SCs) were performed to assess film biocompatibility. A short-time experiment showed improved cell attachment on modified films, in particular when amino groups were present on the material surface. Cell proliferation significantly increased when both treatments were performed, indicating that surface treatments are necessary for SC response. It was also demonstrated that cell morphology was influenced by physico-chemical surface properties. PCL can be used to make artificial conduits and chemical modification of the inner lumen improves biocompatibility.

Surface modification of poly(dimethylsiloxane) microchips using a double-chained cationic surfactant for efficiently resolving fluorescent dye adsorption

This paper described a double-chained cationic surfactant, didodecyldimethylammonium bromide (DDAB). for dynamic surface modification of poly(dimethylsiloxane) (PDMS) microchips to reduce the fluorescent dyes adsorption onto the microchannel. When DDAB with a high concentration was present as the dynamic modification reagent in the running and sample buffer, it not only reversed the direction of electroosmotic flow, but also efficiently suppressed fluorescent dyes pyronine Y (PY) or rhodamine 8 (RB) adsorption onto the chip surface. In addition, vesicles formed by DDAB in the buffer with higher surface charge density and electrophoretic mobility could provide wider migration window and potential for the separation of compounds with similar hydrophobicity. Factors affecting modification, such as pH and concentrations of the buffer, DDAB concentration in the buffer were investigated. Compared with commonly used single-chained cetyltrimethylammonium bromide, DDAB provided a better modification performance.