Mikel Morvan

Stabilization and controlled association of inorganic nanoparticles using block copolymers

We report on the structural properties of mixed aggregates made from rare-earth inorganic nanoparticles (radius 20 A) and polyelectrolyte-neutral block copolymers in aqueous solutions. Using scattering experiments and Monte Carlo simulations, we show that these mixed aggregates have a hierarchical core-shell microstructure. The core is made of densely packed nanoparticles and it is surrounded by a corona of neutral chains. This microstructure results from a process of controlled association and confers to the hybrid aggregates a remarkable colloidal stability.

An Integrated Workflow for Chemical EOR Pilot Design

After primary and secondary production of oil from a petroleum reservoir, more than half of the oil is often left in place. In order to improve the process displacement efficiency – so that one can recover some of this remaining capillary-trapped or water-by-passed oil –, it is necessary to apply enhanced oil recovery (EOR) techniques such as surfactant flooding, either Surfactant (S), Surfactant-Polymer (SP) or Alkaline-Surfactant-Polymer (ASP).

Interactions Between Polymers and Nanoparticles: Formation of “Supermicellar” Hybrid Aggregates

Abstract When polyelectrolyte‐neutral block copolymers are mixed in solutions to oppositely charged species (e.g., surfactant micelles, macromolecules, proteins, etc.), there is the formation of stable “supermicellar” aggregates combining both components. The resulting colloidal complexes exhibit a core‐shell structure, and the mechanism yielding to their formation is electrostatic self‐assembly. In this contribution, we report on the structural properties of “supermicellar” aggregates made from yttrium‐based inorganic nanoparticles (radius 2 nm) and polyelectrolyte‐neutral block copolymers in aqueous solutions. The yttrium hydroxyacetate particles were chosen as a model system for inorganic colloids, and also for their use in industrial applications as precursors for ceramic and opto‐electronic materials. The copolymers placed under scrutiny are the water‐soluble and asymmetric poly(sodium acrylate)‐b‐poly(acrylamide) diblocks. Using static and dynamical light‐scattering experiments, we demonstrate the analogy between surfactant micelles and nanoparticles in the complexation phenomenon with oppositely charged polymers. We also determine the sizes and the aggregation numbers of the hybrid organic–inorganic complexes. Several additional properties are discussed, such as the remarkable stability of the hybrid aggregates and the dependence of their sizes on the mixing conditions.

Fractured Carbonates: A Methodology to Evaluate Surfactant Performances

Wettability alteration is a key method for recovering oil from naturally-fractured, oilwet carbonate reservoirs. Many surfactants have been proposed for this purpose, including sulfonates, alkyl ammonium bromides or ethoxylated alcohols. Nevertheless, the very intrinsic link between oil recovery from an initially oil-wet rock and surfactant characteristics has been poorly studied. In particular, the interplay between rock wettability alteration and oil/water interfacial tension (IFT) reduction due to chemicals is not fully described.