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Grafted Layer (grafted + layer)
Selected AbstractsMultistep Anchoring Route of Luminescent (5-Amino-1,10-phenanthroline)tris(dibenzoylmethane)europium(III) on Si(100)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2010Guglielmo G. Condorelli Abstract A multistep route for the covalent anchoring of (5-amino-1,10-phenanthroline)tris(dibenzoylmethane)europium(III)molecules on silicon (100) has been developed. The anchoring route consists of Si functionalization with N -hydroxysuccinimide (NHS) activated carboxylic acid, followed by nucleophilic substitution at the carboxylic acid sites. Characterization of the resulting Si based hybrid materials was achieved by using several complementary techniques: X-ray photoelectron spectroscopy (XPS), attenuated total reflection FTIR spectroscopy (ATR-FTIR), AFM and fluorescence spectroscopy. Comparison of results obtained for NHS activated Si surfaces with those of inert alkyl functionalized Si surfaces proved the covalent anchoring of the Eu complex and ruled out the presence of physisorbed Eu species. The 1.8 nm thickness of the grafted layer, estimated by atomic-force lithography, is compatible with the presence of the anchored complex on the surface. Fluorescence measurements proved that luminescence properties are retained in the grafted complex. [source] Synthetic Hydrophilic Materials with Tunable Strength and a Range of Hydrophobic Interactions,ADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Olha Hoy Abstract The ability to vary, adjust, and control hydrophobic interactions is crucial in manipulating interactions between biological objects and the surface of synthetic materials in aqueous environment. To this end a grafted polymer layer (multi-component mixed polymer brush) is synthesized that is capable of reversibly exposing nanometer-sized hydrophobic fragments at its hydrophilic surface and of tuning, turning on, and turning off the hydrophobic interactions. The reversible switching occurs in response to changes in the environment and alters the strength and range of attractive interactions between the layer and hydrophobic or amphiphilic probes in water. The grafted layer retains its overall hydrophilicity, while local hydrophobic forces enable the grafted layer to sense and attract the hydrophobic domains of protein molecules dissolved in the aqueous environment. The hydrophobic interactions between the material and a hydrophobic probe are investigated using atomic force microscopy measurements and a long-range attractive and contact-adhesive interaction between the material and the probe is observed, which is controlled by environmental conditions. Switching of the layer exterior is also confirmed via protein adsorption measurements. [source] Distribution of acrylic acid grafted chains introduced into polyethylene film by simultaneous radiation grafting with water and ethanol as solventsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Zhengchi Hou Abstract The graft copolymerization of acrylic acid onto low-density polyethylene films by simultaneous ,-ray irradiation was carried out. The effect of water and ethanol as grafting solvents on the distribution of grafted poly (acrylic acid) in the low-density polyethylene films was studied with optical microscopy observations of dyed and sliced samples and attenuated total reflection/Fourier infrared spectroscopy analysis. When no vigorous homopolymerization occurred, both polyethylene and poly(acrylic acid) existed in the grafted layer, and the thickness of the grafted layer and the poly(acrylic acid) concentration in the grafted layer increased with an increasing degree of grafting, regardless of the grafting conditions, the former increasing faster than the latter. In comparison with water as the solvent, in the absence of the inhibitor, homopolymerization could be suppressed to a certain degree in the ethanol solvent system, whereas in the presence of the inhibitor, obvious homopolymerization occurred at a lower monomer concentration, and both the degree of grafting and the thickness of the grafted layer were lower. Such differences could be explained by the chain transfer and the relatively low solubility of poly(acrylic acid) in ethanol. In addition, an experimental scheme using optical microscopy to observe the dyed and sliced polymers was optimized. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1570,1577, 2007 [source] Gating Characteristics of Thermo-Responsive Membranes with Grafted Linear and Crosslinked Poly(N -isopropylacrylamide) GatesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 4 2009Y.-C. Chen Abstract Thermo-responsive porous membranes with grafted linear and crosslinked poly(N -isopropylacrylamide) (PNIPAM) gates are successfully prepared at temperatures above and below the lower critical solution temperature (LCST) of PNIPAM by using a plasma-induced grafting polymerization method, and the effects of operation pressure and grafting temperature on the thermo-responsive gating characteristics of the prepared membranes are investigated systematically. The fluxes of water through the grafted membranes increase simply with increasing the operation pressure no matter whether the environmental temperature is 40,°C or 25,°C. Under high operation pressure (e.g., higher than 0.14,MPa), the grafted linear PNIPAM gates deform to a certain extent, whereas the grafted crosslinked PNIPAM gates do not deform. For both membranes with grafted linear and crosslinked PNIPAM gates, the membranes prepared at 25,°C (below the LCST of PNIPAM) show larger thermo-responsive gating coefficients than those prepared at 40,°C (above the LCST of PNIPAM), which results from different distributions of grafted PNIPAM gates in the membrane pores. When the PNIPAM gates are grafted at 25,°C, the grafted layer near the membrane surface is much thicker than that inside the membrane pores; on the other hand, when the PNIPAM gates are grafted at 40,°C, the grafted layer is homogeneously formed throughout the whole pore length. Both linear and crosslinked grafted PNIPAM gates in the membrane pores exhibit stable and repeatable thermo-responsive "open-close" switch performances under the operation pressure of 0.26,MPa. The results in this study provide valuable guidance for designing, fabricating, and operating thermo-responsive gating membranes with desirable performances. [source] | |||||||||||||