Surface modification method

In a previous section, the effect of plasma on PVA surface for pervaporation processes was also mentioned. In fact, plasma treatment is a surface-modification method to control the hydrophilicity-hydrophobicity balance of polymer materials in order to optimize their properties in various domains, such as adhesion, biocompatibility and membrane-separation techniques. Non-porous PVA membranes were prepared by the cast-evaporating method and covered with an allyl alcohol or acrylic acid plasma-polymerized layer the effect of plasma treatment on the increase of PVA membrane surface hydrophobicity was checked [37].The allyl alcohol plasma layer was weakly crosslinked, in contrast to the acrylic acid layer. The best results for the dehydration of ethanol were obtained using allyl alcohol treatment. The selectivity of treated membrane (H20 wt% in the pervaporate in the range 83-92 and a water selectivity, aH2o, of 250 at 25 °C) is higher than that of the non-treated one (aH2o = 19) as well as that of the acrylic acid treated membrane (aH2o = 22). 

Amylose brushes (a layer consisting of polymer chains dangling in a solvent with one end attached to a surface is frequently referred to as a polymer brush) on spherical and planar surfaces can have several advantageous uses, such as detoxification of surfaces etc. The modification of surfaces with thin polymer films is widely used to tailor surface properties such as wettability, biocompatibility, corrosion resistance, and friction [142-144]. The advantage of polymer brushes over other surface modification methods like self-assembled monolayers is their mechanical and chemical robustness, coupled with a high degree of synthetic flexibility towards the introduction of a variety of functional groups. 

Table 7.20 Some Surface Modification Methods for Biomaterials...

The principal mineral fillers used in thermoplastics and the reasons for using them are identified, together with those features that have to be controlled in order to achieve the optimum results and to avoid associated deleterious effects. General methods of filler production are outlined in the light of these requirements and their application to the fillers in most use is described. Attention is given to the use of surface modification methods where these are part of the production process. 

All electrodes react with their environment via the surfaces in ways which will determine their electrochemical performance. Properly selected surface modification can effectively enhance the electrode heterogeneous catalysis property, especially selectivity and activity. The bulk materials can be chosen to provide mechanical, chemical, electrical, and structural integrity. In this part, several surface modification methods will be introduced in terms of metal film deposition, metal ion implantation, electrochemical activation, organic surface coating, nanoparticle deposition, glucose oxidase (GOx) enzyme-modified electrode, and DNA-modified electrode. 

Chemical surface modification methods of gas-separation membranes include treatment with fluorine, chlorine, bromine, or ozone. These treatments result in an increase in membrane selectivity with a decrease in flux. Cross-linking of polymers is often applied to improve the chemical stability and selectivity of membranes for reverse osmosis, pervaporation, and gas-separation applications (41). Mosqueda-Jimenez and co-workers studied the addition of surface modifying macromolecules, and the use of the additive... 

At present, the techniques to modify zeolite channels and surface can be classified as three categories that is, cation-exchange method, channel modification, and surface-modification methods. 

In the development of the electrode surface modification method, nano-regulation of the surface films with inorganic nanoclusters and molecular-level tracking of the dynamic phase transition are highlighted. Eor the in-situ characterization of such electrode surfaces covered with a monolayer-level organic film or organic molecule-nanocluster hybrid film, UV-visible reflectance spectroscopy... 

Hibara, A., Iwayama, S., Matsuoka, S., Ueno, M., Kikutani, Y, Tokeshi, M. and Kitamori, T., Surface modification method of microchannels for gas-liquid two phase flow in microchips. Anal Chem, 11, 943, 2005. 

Another commonly used surface modification method of the reinforcing fibers consists in the treatment with aminoalkylsilanes, for example y-aminopropyltriethoxysilane. Glass fibers, which have been sized in this manner, are incorporated in numerous PPE-containing compositions. In addition, it is always necessary to modify the composition of the thermoplastic matrix to bond the fibers to the matrix. In addition to glass fibers, carbon fibers, e.g., epoxy resin-sized carbon fibers have been used for reinforcement. ... 

J. Yang, et al.. Enhancing the cell affinity of macroporous poly(L-lactide) cell scaffold by a convenient surface modification method. Polym. Int. 52 (2003) 1892-1899, doi 10.1002/pi.l272. 

In this study, in order to improve the adhesion properties of aramid fibers to rubber as matrix, nylon thin films were securely formed on the surfaces of the aramid fibers by a radio frequency ion-plating (RFIP) method which represents an application of low temperature plasma treatment. These fibers were coated with a RFL (resorcinol-formaldehyde-latcx) adhesive which has high affinity to both nylon and rubber The adhesion properties of the fibers to rubber were evaluated, and the effects of the RFIP method were confirmed by a comparison of the RFIP treated fibers with those subjected to the low temperature plasma treatment. The usefulness of such surface modification methods will be discussed. 

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