Stabilisation of Thin Liquid Films by Polymer Additives

Stability of thin films of non-volatile liquids is a key issue in a variety of applications. Often a film is forced to spread on a substrate which is not wetted by the liquid. The film then ruptures within minutes and dewets. Common methods for achieving stability include the introduction of surface-active low molecular weight agents, or modification of the chemistry of the substrate. We describe here a mechanism for suppressing the rupture of the films by surface-attached polymers together with trace amounts of free polymers in the bulk of the film. The effect may have a kinetic origin, which is related to the entanglement of free chains and surface-attached polymer chains, or it may be due to a modification of the thermodynamic interactions.