I am considering a suspension of a fine powder in a high-viscosity liquid. The suspension shall be stable over long time scales, i.e. the particles only move a few mm per year, and I have the following boundary conditions:
- The particles sizes shall be between 0.1 and 1.0 microns, so the suspension is colloidal
- The concentration of dispersed particles in the medium is high (the phases have approximately equal volume).
- The viscosity of the medium must be high. I am considering >10000 cSt, which is comparable to thick honey or shower gels
- The medium will also be free of water; possibly long hydrocarbons
In a first naïve treatment with Stokes' law I thought that such a suspension should be sufficiently stable. Then I read about interparticle effects, which can lead to agglomeration of the particles and sedimentation (mainly on wikipedia). I don't know yet which material will be used as the solid powder, so I have to consider the worst case of attracting forces between the particles, so that there will be agglomeration and sedimentation in my case. This has to be prevented, but for several reasons I would like to avoid steric stabilization.
However, all examples of agglomeration considered a "thin" liquid like water, while polymeric stabilization technique is based on long polymer chains in the medium. Since in my case the viscosity of the medium is very high in my case, I wondered if this might be enough to prevent agglomeration. The high viscosity is due to long molecular chains, so I'm thinking that this might count as a case of polymeric stabilization. Is it possible to prevent agglomeration and sedimentation of microparticles just by increasing the viscosity of the medium?