Multilayers conformational changes

By careful examination of the XPS Cls spectra it was possible to relate small changes in the relative position of the methoxy and ester components to specific interactions between the polymer and the metal substrates. The type of bonding observed depends strongly on the acido-basic properties of the metal oxide. The adsorption isotherms from these systems were not simple to interpret, as polymer conformation changes as the solution concentration increased gave the erroneous appearance of multilayer deposition [11]. 

Multi-layer sorption, on the other hand, would have to involve an interaction between mannan chains themselves. Mannan sorption seems, however, to be built up of two stages firstly, the initial very rapid sorption, followed by a much slower sorption phase, which may be the multilayer sorption (20). A change in the mannan conformation after sorption may perhaps enable or facilitate mannan - mannan interactions and allow multilayer sorption. Studies at our laboratory on sorption of mannans onto bleached kraft pulp (BKP) showed that sorption of a high-molar-mass GM was not affected by the presence of a layer of presorbed low-molar-mass GM, and vice versa (31). Furthermore, sorption onto mechanical pulp fibers, which already contain high amounts of hemicelluloses and probably little, if any free cellulosic surfaces, has also been achieved with certain mannans. This point will be further discussed in the next chapter. 

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