25 июня, 2015 
Malyar X-ray Photoelectron Spectroscopy (XPS) has been used extensively in adhesion research for determining surface functional groups, studying the locus of failure of adhesive joints, determining molecular orientation following failure [135,136], monitoring the uptake of specific ions [137,138] at the interface, and identifying molecular species segregating at polymer-metal oxide interfaces [139-141]. It has also been found to be effective in determining adsorption isotherms of silane coupling agents onto metal oxides [142-145], and flexible polymers onto metal oxides [146] and stiff conducting polymer particles [147,148]. In the last case, the XPS results were interpreted in terms of acid-base interactions of the adsorbate, the conducting polymer and the casting solvent [147-149].
The success of XPS lies in its surface specificity (analysis depth of ca. 5 nm), low degree of degradation of tested materials, quantitative aspect, and detection of all elements (except hydrogen) and their chemical shifts. The so-called chemical shift is the cornerstone of XPS since it enables the surface scientist to study chemical bonding and to derive materials properties such as refractive indices of thin optical layers [150], the nondispersive component of the surface energy of polymers [151] and the acid-base properties of alcohols and amines [152].
In this section, we shall examine three approaches for the assessement of acid-base properties of molecules, polymers, and metal oxides by XPS:
(i) ion-exchange experiments to characterize hydroxylated metal oxide surfaces;
(ii) the use of the intrinsic chemical shifts experienced by the materials under investigation;
(iii) chemical shifts of molecular probes induced by specific adsorption onto polymers.
Опубликовано в рубрике 