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Rhelogical Behavior of Aqueous Mixtures of PB-PEO Amphipilic Diblock Copolymer and Surfactants

Mixtures of surfactants and amphiphilic block-copolymers provide a model for lipid protein interaction and are typical components in emulsions and microemulsions, also they are used as templates in the preparation of nanostructured materials and nanoparticles. Co-micellisation of the di-block copolymer polybutadiene-poly(ethylene oxide) (PB-b-PEO) with the anionic (sodium dodecylsulfate (SDS)) and zwiterionic (tetradecyl dimethylammonium propane sulfonate (TDPS) surfactant was investigated in aqueous solution using different techniques (Rheology, DLS, TEM/HAADF, AFM and CLM). In dilute aqueous solutions this polymer forms large wormlike micelles agregates which were detected by TEM/HAADF. Upon addition of the small concentration of both surfactants (below cmc), the large wormlike block copolymer micelles agregates exhibit a structural change, and worm like micelles are expanded and form a large entanglament networks. This structural change is accompanied with increasing in the viscosity of systems. Further addition of both surfactants (abow cmc) entanglament network is completely destroyed and worm like micelles are transformed into sferical micelles. This structural change is accompanied with decreasing of viscosity and systems are transparent. All this changes in the structures are connected with decreasing of core interfacial energy6. In this investigation we demostrated a exsitance of strong interaction between amphiphilic doblock copolymer (PB-PEO) and different surfactants (TDPS, SDS). This nonelectrostatic interactions changed complitely the state of polymer aqueous dispersion. This results are very important for understanding the interactions between amphiphilic diblock copolymers and surfactants, which could lead to the better understandig of behaviour and properties in complex fluids.

diblock copolymer; surfactants; self-assembly

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