Small-Angle Neutron Scattering study of solubilization of tributyl phosphate in aqueous solutions of L64 Pluronic triblock copolymers

Jeremy Causse (1, 2) , Julian Oberdisse (3) , Jacques Jestin (4) , Serge Lagerge (1)

1 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
2 LPAD - Laboratoire des Procédés Avancés de Décontamination
3 LCVN - Laboratoire des colloïdes, verres et nanomatériaux
4 LLB - UMR 12 - Laboratoire Léon Brillouin

We have studied the solubilization behaviour of tributylphosphate (TBP) in aqueous solutions of L64-Pluronics, using light and small angle neutron scattering (SANS). Varying the temperature and the oil-content, the system presents a non trivial phase behaviour. In particular, at 308K, a first solubilization followed by an emulsification failure and a resolubilization is found. We have measured the microstructure by SANS and characterized the microemulsion droplet core-size, corona-thickness, polydispersity, and interactions. It is shown that at low oil content, the system is made of small swollen micelles. After the phase separation, the resolubilization is carried by larger oil droplets decorated by copolymer. From specific surface measurements at large angles, a surprising change in surfactant conformation is found to accompany this morphological evolution which is also supported by previous results obtained from 1H NMR experiments. In independent measurements, our structural modelling is confirmed using contrast-variation SANS.

Domaines: Matière Molle [cond-mat.soft]

Jeremy Causse, Julian Oberdisse, Jacques Jestin, Serge Lagerge. Small-Angle Neutron Scattering study of solubilization of tributyl phosphate in aqueous solutions of L64 Pluronic triblock copolymers. Langmuir, 2010, 26 (20), pp.15745-15753. ⟨10.1021/la1021164⟩. ⟨hal-00542822⟩