| Abstract
| - The adsorption behavior of self-assembled lipid liquid crystalline nanoparticles at different model surfaces wasinvestigated in situ by use of ellipsometry. The technique allows time-resolved monitoring of the adsorbed amountand layer thickness under transient and steady-state conditions. The system under study was cubic-phase nanoparticle(CPNP) dispersions of glycerol monooleate stabilized by a nonionic block copolymer, Pluronic F-127. Dependingon the surface properties and presence of electrolytes, different adsorption scenarios were discerned: At hydrophilicsilica thick surface layers of CPNPs are generated by particle adsorption from dispersions containing added electrolyte,but no adsorption is observed in pure water. Adsorption at the hydrophobic surface involves extensive structuralrelaxation and formation, which is not electrolyte sensitive, of a classic monolayer structure. The different observationsare rationalized in terms of differences in interactions among the CPNP aggregates, their unimer constituents, andthe surface and show a strong influence of interfacial interactions on structure formation. Surface self-assemblystructures with properties similar to those of the corresponding bulk aggregates appear exclusively in the weakinteraction limit. This observation is in agreement with observations for surfactant self-assembly systems, and ourfindings indicate that this behavior is applicable also to complex self-assembly structures such as the CPNP structuresdiscussed herein.
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