Wetting Behavior in Colloid−Polymer Mixtures at Different Substrates

We present experimental observations on wetting phenomena in depletion interaction driven, phase separated colloidal dispersions. The contact angle of the colloidal liquid−gas interface at a solid substrate was determined for a series of compositions. Upon approach to the critical point, a transition occurs from partial to complete wetting. The interaction with the substrate was manipulated by modifying the substrate with a polymer. In that case, a transition from partial to complete drying is observed upon approach to the critical point.