Surface modification

About: Surface modification is a research topic. Over the lifetime, 35544 publications have been published within this topic receiving 859567 citations.

The Effect of Alkali Treatment on the Adhesion Characteristics of Sisal Fibres

Abstract: The effect of alkali treatment on the wetting ability and coherence of sisal-epoxy composites has been examined. Treatment of sisal fibre in a 0.5N solution of sodium hydroxide, resulted into more rigid composites with lower porosity and hence higher density. The treatment has been shown to improve the adhesion characteristics, due to improved work of adhesion because it increases the surface tension and surface roughness. The resulting composites showed improvements in the compressive strength and water resistance. It has been suggested that the removal of intracrystalline and intercrystalline lignin and other surface waxy substances by the alkali substantially increases the possibility for mechanical interlocking and chemical bonding. The alkali treatment is simple and is recommended to precede other sophisticated surface modification treatments on plant fibres similar to sisal fibre.

Effects of Surfactant Structure on the Phase Inversion of Emulsions Stabilized by Mixtures of Silica Nanoparticles and Cationic Surfactant

Abstract: Silica nanoparticles without any surface modification are not surface active at the toluene−water interface due to their extreme hydrophilicity but can be surface activated in situ by adsorbing cationic surfactant from water. This work investigates the effects of the molecular structure of water-soluble cationic surfactant on the surface activation of the nanoparticles by emulsion characterization, adsorption and zeta potential measurements, dispersion stability experiments, and determination of relevant contact angles. The results show that an adsorbed cationic surfactant monolayer on particle surfaces is responsible for the wettability modification of the particles. In the presence of a trace amount of cationic surfactant, the hydrophobicity of the particles increases, leading to the formation of stable oil-in-water O/W(1) emulsions. At high surfactant concentration (>cmc) the particle surface is retransformed to hydrophilic due to double-layer or hemimicelle formation, and the concentration of the free...

Super-hydrophobic surfaces of layer-by-layer structured film-coated electrospun nanofibrous membranes

Abstract: We have recently fabricated super-hydrophobic membrane surfaces based on the inspiration of self-cleaning silver ragwort leaves. This biomimetic super-hydrophobic surface was composed of fluoroalkylsilane (FAS)-modified layer-by-layer (LBL) structured film-coated electrospun nanofibrous membranes. The rough fibre surface caused by the electrostatic LBL coating of TiO2 nanoparticles and poly(acrylic acid) (PAA) was used to imitate the rough surface of nanosized grooves along the silver ragwort leaf fibre axis. The results showed that the FAS modification was the key process for increasing the surface hydrophobicity of the fibrous membranes. Additionally, the dependence of the hydrophobicity of the membrane surfaces upon the number of LBL coating bilayers was affected by the membrane surface roughness. Moreover, x-ray photoelectron spectroscopy (XPS) results further indicated that the surface of LBL film-coated fibres absorbed more fluoro groups than the fibre surface without the LBL coating. A (TiO2/PAA)10 film-coated cellulose acetate nanofibrous membrane with FAS surface modification showed the highest water contact angle of 162° and lowest water-roll angle of 2°.

Attaching organic layers to semiconductor surfaces

Abstract: Methods that can be used to tailor the surface properties of semiconductors will become increasingly important as new applications for semiconductor-based materials continue to be developed. The attachment of organic groups in particular can impart new functionality to the surface, providing properties such as passivation, molecular recognition, lubrication, or biocompatibility. This article will focus on organic functionalization of Group IV surfaces using vapor phase delivery in a dry processing environment. A combination of experimental and theoretical methods has been applied to identify the bonding and reactivity of the organic layers at the semiconductor surface. The attachment chemistry of dienes and amines at the Si(100)-2 × 1 surface will be described. We show that the [4+2] cycloaddition (Diels−Alder reaction) occurs readily for a range of conjugated dienes at the (100)-2 × 1 surface of Si, and that the reaction occurs at the surfaces of Ge(100) and C(100) as well. In amine reactivity, competing...