A phoretic mechanism of colloids, is any mechanism/effect that causes colloidal particles to move in a way that is partially deterministic (unlike Diffusion), due to the gradient of some physical quantity (This seems to be the working definition, judging from what I've read). These may also called transport mechanisms.
These are important in Active matter, in Biophysics, and Nanotechnology. In particular phoretic effects can make a colloidal particle self-propelling.
A large class of mechanism for colloid transport are due to interfacial forces, due to non-trivial Microhydrodynamics, Chemical reactions, or other effects.
See Colloid Transport by Interfacial Forces. See also the more recent Manipulation of Colloids by Osmotic Forces
Generic theory of colloidal transport
Thermal non-equilibrium transport in colloids