Surfactant enhanced spreading on polymeric substrates of various surface energy

CAW does not provide a complete substrate characterisation for spreading of surfactant solutions: the same solution demonstrated different spreading kinetics on different substrates with the same CAW. Spreading kinetics was characterised by the dependence of spread area, A, with time, t, being A∝t^α. For complete wetting, all surfactant solutions on all substrates began the spreading process with a spreading exponent α ≤ 0.5, but two of them later went into superspreading mode with α ≥ 1. On substrates with the highest and lowest surface energy, superspreading solutions begin spreading with α ∼ 0.2, similar to pure liquids. On some substrates only spreading with α ∼ 0.2 was observed.