Stiffness/steric interactions

In previous force measurements we found that the interactions between xylan-coated mica surfaces were dominated by steric forces (8). In that work we argued that due to the stiffness of the xylan molecule, fitting to other theories of polymer interaction is not straightforward. The adsorbed xylan layo was ratho thick in that study. However, in another investigation (32) it was found that electrostatic repulsion dominated the interactions between xylan-coated mica surfaces at large distances. In that case the adsorption of xylan was very limited and the layer thin. These results agree with our conclusions that steric factors become dominating when the adsorption of xylan increases. 

Figure 5.8 Schematic representation of three alternative effects of the adsorption of stiff hydrocolloid polymers on the surface of spherical emulsion droplets, depending on the hydrocolloid concentration and the nature of the hydrocolloid-protein interaction (a) A sterically stabilized system, b) an emulsion gel, and (c) a system flocculated by macromolecular bridging (Dickinson, 2003).

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