Thin Films at Interfaces

Andrew Nelson, ANSTO

Adsorbed polymer films have a large impact in the colloidal domain, as surface modification often changes properties of the systems they are added to.

In this talk we examine the effects of surface modification in two different systems.

The first system considers plasma polymer coatings, which adhere to and contour the surfaces of most organic and inorganic materials. These coatings are attractive as surface chemical modification systems, since they are robust, impermeable and offer inherent functionality for further surface derivatisation. In order to optimise the film properties the internal structure of these films was probed with multiple contrast reflectometry. This contrast series provided important information on film composition and density, as well as the structural changes when exposed to water.

The second system examines the conformation of adsorbed polymer (PEO + Pluronics) layers on Laponite particles. This system is special, since the anisotropic nature of the particle produces unusual changes in the conformation of the adsorbed polymer. Contrast-variation SANS measurements reveal that polymer is present on the face of the clay particle ans that it also extends or "wraps" over the edges. The PEO polymers form thin adsorbed layers that show little change with Mw, whilst the Pluronics take on an extended conformation.

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