Suppression of rupture in thin, nonwetting liquid films.

Stabilization against the rupture and breakup of thin, nonwetting liquid films spread on surfaces is generally sought by modification of equilibrium interfacial properties. A mechanism for suppressing rupture in such films that uses surface-attached polymers togetherwithfree chains in the bulk of the film is reported. Films of an oligostyrene liquid, which rupture within several minutes when spread on a silicon wafer, may be stabilized for many months by a polystyrene brush attached to the substrate, together with some free polystyrene in the liquid. The effect may arise from entanglements of the free chains with the immobilized brush.

Salting-in effect in organic dispersions of poly(3-hexyl thiophene)-carbon-nanotubes.

Addition of small concentrations of different inorganic salts to THF solutions of poly(3-hexyl thiophene), which contain non-dispersed powder of Multi-Walled Carbon Nanotubes (MWNTs), was found to "salt-in" the precipitated tubes leading to the formation of a stable dispersion of the MWNTs. This effect seems to result from a salt-induced conformational change of polymer chains adsorbed onto the CNTs, resulting in the onset of (entropic) steric repulsion among polymer-decorated chains.

Alternative dewetting pathways of thin liquid films

An alternative pathway for the initiation of dewetting in thin metastable films of partially miscible liquid mixtures is described. In this pathway, phase separation is followed by a dewetting process at the interface between the two phases. Dewetting proceeds (from the sample edges inward) as holes form. The initially smooth film breaks up into droplets at rates much faster than those allowed by classical rupture mechanisms. Marangoni flow appears to be responsible for the initiation of the flow of the dewetting front, and coupling between the flow in the two phases leads to accelerated hole formation.