Forces between xylan-coated

Forces between xylan-coated cellulose spheres... 

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. 

The force curves were recorded 1-2 h after changing the xylan concentration. The QCM-D measurements suggested that the adsorption reached a plateu value only after about 3 h. No firm conclusions can be drawn about the nature of the interactions between the xylan-coated surfaces based on these experiments. The effect of electrolyte concentration should be investigated to clarify whether the forces are purely electrostatic or not. This is done in an ongoing study. 

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