Surface modifying effects techniques

Some of the commonly used techniques for measuring contact angle [215, 216, 217] are the sessile drop method, captive bubble method and Wilhelmy plate method. These techniques have been extensively used and well documented for characterisation of modified PE surfaces [218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230] for various applications. Whitesides et al. [231 ] studied the wetting of flame-treated polyethylene film having ionisable organic acids and bases at the polymer-water interface. The effect of the size of substituted alkyl groups in amide and ester moieties on the surface hydrophilicity was also studied [232]. The biocompatibility of the polyethylene film surface modified with various water-soluble polymers was evaluated using the same technique [233]. The surface properties of hy-perbranched polymers have been very recently reported [234]. 

Therefore, Equations 8.48 and 8.49 can be combined into one equation for concentration only. The effectiveness factor for the case considered can be calculated with the technique described in Chapter 7. It is important to stress that the effectiveness factor changes along the reactor because parameters of the reaction rate expression, Equation 6.18, e and a depend on the surface concentration and temperature. The calculated modified effectiveness factors for nonisothermal first-order reaction at different conversions = (1- CAJCa) are shown in Figure 8.9 versus the ratio of inner and outer diameters of the hollow cylinder. The parameters chosen for the calculation are ... 

Zeolite shells on polystyrene beads were prepared by a combination of layer-by-layer (LbL) and hydrothermal synthesis techniques. The negatively charged polystyrene beads were surface modified in order to adsorb zeolite Beta nanocrystals. Such particles were then adsorbed on the surface of the beads and induced to grow into a continuous film of intergrown crystals of zeolite Beta. The effect of the preliminary treatment on the formation of the zeolite film was studied. Finally the polystyrene beads used as macro-templates were removed by calcination in air, yielding hollow spheres of zeolite Beta. The zeolite Beta/polystyrene composites and the corresponding hollow zeolite spheres were characterized by XRD, SEM, TG/DTA and BET surface area measurements. 

Due to a pronounced optical anisotropy of ordered liquid crystals, reflection elhpsometry is a powerful experimental tool for the study of surface-modified liquid crystalline order. The sensitivity of the technique enables quantitative measurements of the nematic order parameter profile at the interfaces. Prom observation of the nematic wetting of the solid-liquid crystal interface, we have determined the values of the coupling energies between the surface and the nematic order. Even the pretransitional effects at solid-smectic liquid crystals can be studied with elhpsometry due to the strong coupling between the nematic and the smectic order. The time evolution of the complex structure of the liquid crystal adsorbate on a solid substi ate has also been successfully monitored using BAE. 

SERRS spectroscopic and ER voltammetric techniques were used to investigate the effect of surface modifiers, 11-mercaptoundecanoic acid (11-MUDA) and 4,4 -bipy, on the structure and redox properties of cyt. C3 from D. desulfuricans, Norway strain, at a silver electrode [47]. The ER voltammograms of cyt. C3 immobilized on... 

UV irradiation of polymers has been observed to be an effective technique to modify polymers for biomolecule immobilization. The polymer surface is modified by photo-induced graft polymerization of different monomers, such as acrylic acid,. -acrylamidomethylpropane sulfonic acid, and styrene sulfonic acid. All these monomers have ionic functionality and lead to high graft densities for the immobilization of collagen and other proteins. The surface density of polyacrylic acid grafts reaches up to lOOpg/cm under appropriate reaction conditions and Is enough for protein immobilization [36]. 

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