Phenol solubilization in aqueous Pluronic® solutions: Investigating the micellar growth and interaction as a function of Pluronic® composition

Abstract

Pluronics® are considered as potential materials for the removal of contaminants like phenol from polluted water sources because of their superior solubilizing capacity of aromatic compounds. Systematic studies on the influence of solubilization of phenol on room temperature aggregation characteristics of Pluronics® in water are, however, conspicuous by their absence. In this manuscript, we thus report DLS, SANS and rheological studies on the influence of phenol on the aggregation characteristics of four Pluronics® viz. F127, P123, P104 and P103. The aim of this study has been to understand the role played by the composition of the Pluronics® in determining growth and interaction of the micelles induced by solubilization of phenol. The study shows that in the case of F127 and P123, phenol solubilization leads to a large increase in light scattering intensity due to an onset of attractive intermicellar interactions and consequent formation of micellar clusters. P123 being smaller than F127 shows a subsequent time dependent micellar growth, leading to a sphere-to-rod shape transitions in micelles. The copolymers P103 and P104, which are smaller and less hydrophobic than P123, respectively, exhibit a large increase in solution viscosity in the presence of phenol owing to a rapid sphere-to-rod micellar growth. The observation of such a fine interplay between the growth and interaction of the pluronic micelles in the presence of a hydrophobic solvent is first of its kind and highlights the role of composition of pluronic in determining the kinetics of the micellar restructuring process.