Effects of Charge

What can make electrostatic interactions more significant?

1. Increase the size of the particle.Electrostatic forces as R² whereas van der Waals forces vary linearly with R.
2. Increase the surface-charge density.The critical radius varies as 1/s².
3. Decrease the surface energy/Hamaker constant.Examples include coating a surface with Teflon or zinc stearate.
4. Add asperities to the particle.These serve as physical separations that reduce adhesion (Tabor and Fuller (Proc. R. Soc. Lond. A 345, 327 (1975); Schaefer et al. J. Adhesion Sci. Technol. 9, 1049 (1995))
5. Add neighboring particles having a similar charge (Goel and Spencer, in Adhesion Science and Technology Part B, L. H. Lee (ed.)).
6. Localize charge to specific areas on surface of the particle rather than uniformly distributing it – the so-called “charged patch model” (D.A. Hays, in Fundamentals of Adhesion and Interfaces, D. S. Rimai, L. P. DeMejo, and K. L. Mittal (eds.))