cmc and adsorption onto interface of solution are interrelated but separate phenomena.

If cmc is low due to low solvency adsorption will be high, however, even if there is no cmc only limited solubility there will be also adsorption.

'Dispersancy', maybe you mean dispersibility or solubility? If it can be only dispersed there will be no cmc.

Thanks Titus for your answer.

I meant if there is a correlation between CMC of a dispersant and the extent at wich it interacts with surfaces. In other words how the action of the dispersant towards e.g a solid  is affected by its CMC.

In principle the same applies, however, now complicated by an additional phase which cannot be considered inert towards surfactant and continuous phase, i.e. relation to cmc has to be dependent on these. However, because there is no causal connection between dispersibility and cmc you should not waste time on this. In best case you have specific interaction between solid and surfactant, e.g. as in case between iron oxides and fatty acids you can make solids hydrophobic to be compatible with hydrophobic solvents.

Can you still talk about CMC of nonionic surfactants in non-aqueous solvents? What solvents then? do they have affinity to the surfactant? Only after having defined this new system, you may relate to adsorption (of what?) and dispersibility (of what?). Ciao

Thanks Alessandro for your reply. I had in mind the fate of polyisobutenyl succininanhydrides and their derivatives when dissolved in e.g.toluene, in the presence of solid carbon and as a function of their concentration.