Theoretical investigation on the interaction between a soft particle and a rigid surface

An extension of Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was developed to model the potential energy of interaction between a soft particle (particle coated with either uncharged polymer or polyelectrolyte) and a rigid flat surface prior to the particle-surface contact. An uncharged polymer is predicted to reduce the barrier of interaction energy curve by shifting the contact frontier away from the particle core and as a result increases the affinity between the coated particle and the uncoated surface. For particles coated with polyelectrolyte, the particle–surface interaction is primarily regulated by the thickness and charge density of the polyelectrolyte layer. For either type of coating, increasing ionic strength is predicted to reduce the barrier of interaction potential and thus increase the affinity between the particle and the surface. A more comprehensive model was also established for a polyelectrolyte-coated particle of charged core surface, in which the importance of segment density of the coating layer was demonstrated. Limitations of these models were discussed especially for particles of very low segment density to which the post-contact interaction would become important.