Interfacial behaviour of block polyelectrolytes,III. Formation of surface micelles

The aggregation of (poly)styrene/quaternized (poly)-4-vinylpyridine diblocks into regular circular structures has been observed in Langmuir-Blodgett films removed from a pure water surface. These novel aggregates, termed surface micelles, form at low surface pressures (< 2 mN/m) and exhibit rich isotherm behaviour as Langmuir films. A distinct first order phase transition is observed for the decylated derivatives of a series of diblocks (i.e. (PS)₂₆₀(C₁₀PVP⁺I⁻)_n; n = 70, 120, 240) which has been interpreted as a transition from an entirely surface-adsorbed micelle to a surface micelle whose polyelectrolyte chains have been forced into the aqueous subphase. Transmission electron and atomic force micrographs of LB films provide for direct visualization of these surface micelles as well as the means to estimate their aggregation numbers, N.