scopic ﬁlm. We have seen that the KMC model is able to describe the interplay of solute diffusion
within the solvent and solvent evaporation/condensation. It also takes the liquid-liquid, liquid-
particle and particle-particle interactions into account and therefore allows us to distinguish differ-
ent regimes of the transverse (ﬁngering) instability of the evaporative dewetting front: a transport
regime where the instability is almost completely independent of the interaction strengths and
a demixing regime where particles and liquid demix at the receding front thereby increasing its
transverse instability.
The dynamical density functional theory describes the coupled dynamics of the density ﬁelds of
the liquid and the nanoparticles. In the form described above (i.e. based on the two-dimensional
hamiltonian (3)) we obtain a simple theory that allows us to study the time evolution of the evapo-
rating ultrathin ﬁlm and also to investigate the inﬂuence of processes such as surface diffusion by
the liquid, which are not incorporated in the KMC model. However, it is straightforward to extend
the theory to consider a fully three-dimensional ﬂuid ﬁlm, in which one can distinguish between
short- and long-range interactions of solvent and/or solute with the substrate. We have, however,
restricted the examples given here to situations that can also be described using the KMC model.
A further exploration will be presented elsewhere.
Finally, we have discussed a simple thin ﬁlm model for the hydrodynamics on the mesoscale. It
results from a long-wave approximation and consists of coupled evolution equations for the ﬁlm
thickness proﬁle and the mean particle concentration. It has been used to discuss the self-pinning
of receding contact lines that is related to the formation of rings of dried-in particles (coffee-
stain effect) that frequently occurs when ﬁlms or drops of solutions or suspensions dewet by the
combined effects of convection and evaporation.
One of the primary goals of researchers in this ﬁeld, is the search for simple-to-use techniques
that allow one to produce hierarchically structured functional layers for a wide range of applica-
tions such as, e.g., organic solar cells [98]. This means that the experiments advance very rapidly
towards increasingly complex systems. For example, there have been investigations of the inﬂu-
ence of the phase behaviour on the drying of droplets of a suspension of hard-sphere colloidal
particles and non-adsorbing polymer [99], of the instabilities and the formation of drops in evap-
orating thin ﬁlms of binary solutions [100] that may lead to treelike patterns [101], of effects of
a secondary phase separation on evaporation-induced pattern formation in polymer ﬁlms [102],
and of the inﬂuence of an imposed ﬂow on decomposition and deposition processes in a sliding
ridge of evaporating solution of a binary polymer mixture [103] and of the inﬂuence of rather
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