Poly surface changes

SFG can provide considerable information regarding the buried interface that is of central importance to corrosion inhibition processes. A model system in this respect is the monolayer of benzotriazole (BTA) that forms beneath a thick multilayer of the same molecule on Cu. Two SFG studies have examined this system thus far [125, 126]. In the study by Schultz et al., SFG showed that BTA forms a relatively well-ordered monolayer on Cu(lOO) between -0.7 and -tO.2 V, while on Cu(lll) this order is only present at high potential. Titration with Cl showed that the monolayer was destabilized at lower Cl concentrations than those needed to destabilize the polymeric and somewhat more inaccessible multilayer. Work performed by Romero et al. using 5-methylbenzotriazole on Cu(poly) show that the 5-methylbenzotriazole is stable on the surface with no orientation changes with potential [125]. Similarly to the system studied by Schultz, the degree of preferential ordering of BTA on Cu(lll) seems to be less than that on the Cu(poly) surface. 

Barzin et al. [34] characterized UF poly(ether sulfone) hemodialysis membranes (Chap. 5). The morphologies of both inner and outer surfaces changed on heating either in hot water or in air, and so did the performances of the membranes. The performance data of hollow fibers heated in air at 150 °C was foimd to be the most appropriate for hemodialysis application. 

When stimuli-responsive polymers are attached to a surface, changes in the physicochemical properties of the surface layer that result from an external stimulus can be assessed by AFM in situ. Micropattemed thermoresponsive polymers, such as poly(A-isopropylacrylamide) (PNIPAm), were characterized via AFM height imaging and the brush adhesiveness measured by force spectroscopy during... 

In this case study, surfaces of a commonly consumed plastic polymer, poly(ethylene terephthalate) (PET), were exposed to bacterial communities present in samples of coastal seawater. The PET was the sole carbon and energy source provided for the bacteria, to maximise the desirability for bacteria to interact with the surface. Changes in the elemental and chemical composition of the PET surfaces were detected by XPS. 

As a furtlier example for tire meaning of ex situ investigations of emersed electrodes witli surface analytical teclmiques, results obtained for tire double layer on poly crystalline silver in alkaline solutions are presented in figure C2.10.3. This system is of scientific interest, since tliin silver oxide overlayers (tliickness up to about 5 nm) are fonned for sufficiently anodic potentials, which implies tliat tire adsorjDtion of anions, cations and water can be studied on tire clean metal as well as on an oxide covered surface [55, 56]. For tire latter situation, a changed... 

Materials that typify thermoresponsive behavior are polyethylene—poly (ethylene glycol) copolymers that are used to functionalize the surfaces of polyethylene films (smart surfaces) (20). When the copolymer is immersed in water, the poly(ethylene glycol) functionaUties at the surfaces have solvation behavior similar to poly(ethylene glycol) itself. The abiUty to design a smart surface in these cases is based on the observed behavior of inverse temperature-dependent solubiUty of poly(alkene oxide)s in water. The behavior is used to produce surface-modified polymers that reversibly change their hydrophilicity and solvation with changes in temperatures. Similar behaviors have been observed as a function of changes in pH (21—24). 

This potential reflects itself in the titration curves of weak polyacids such as poly(acrylic acid) and poly(methacrylic acid) [32]. Apparent dissociation constants of such polyacids change with the dissociation degree of the polyacid because the work to remove a proton from the acid site into the bulk water phase depends on the surface potential of the polyelectrolyte. 

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