Particle Deposition in Detergency

Cationic polymers are also sometimes added to certain detergent formulations, as conditioners for some substrates, e.g. wool. The polycations will adsorb on the negatively ciiarged substrate and they will have a pronounced effect on particle deposition. In addition, polycationic polymers will interact strongly with any anionic 

In the absence of any other effects, addition of cationic polyelectrolytes can enhance particle deposition either by simple charge neutralisation or by bridging between the particle and the surface. At high polyelectrolyte concentrations, when there is sufficient molecules to coat both particle and surface, repulsion may occur, resulting in a reduction in deposition. However, these effects are complicated by the interaction of the polycationic polymer with surfactants in the formulation and this complicates the prediction on particle deposition. 

As mentioned above, adhesion is the force necessary to separate adherents it is governed by short-range forces. Adhesion is more complex than deposition and more difficult to measure. The adhesion of dirt to substrates is determined by the same short-range forces described above. As already noted, there is no quantitative theory that can describe all adhesion phenomena Chemical and non-chemical bonds operate. Adequate experimental techniques for measuring adhesion strength in detergency are still lacking. 

Patbuck Treatise on Adhesion and Adhesives, Edward Arnold Publishers, 9 H. C. Hamaker, Physica (Utrecht), 1937, 4, 1058. 

Gibbs The Collected Work of J. Willard Gibbs, Vol. 1, Longman, Harlow, 13 W. D. Harkins, /. Phys. Chem., 1937, 5, 135. 

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