Single and mixed Pluronics® micelles with solubilized hydrophobic additives: Underscoring the aqueous solution demeanor and micellar transition

Abstract

This work aims to optimize the aqueous solution behavior in mixed system of polyethylene oxide-block-polypropylene oxide-block-polyethylene oxide (PEO-PPO-PEO). Two copolymers viz., P123 and F127 (with same size of hydrophobic PPO block and 30 % and 70 % hydrophilic PEO end blocks, respectively) were used and the changes in size self-assembled mixed micelles were examined in the presence of small amount of four very hydrophobic copolymers viz., L61, L81, L101, and L121 (each with 10 % PEO but varying PPO molecular weight). The cloud point (CP) show the changes in the phase behavior of the examined systems while the relative viscosity (ηrel) pointed out marked changes in the flow behaviour. The micellar characteristics (size, shape, aggregation number) determined by dynamic light scattering (DLS) and small-angle neutron scattering (SANS) depict the plausible morphological transition expressed as apparent hydrodynamic diameter (Dh), hard sphere radius (Rhs), aggregation number (Nagg) at different temperatures. Such modulations in the mixed Pluronics® systems are further examined for the solubilization of hydrophobic anticancer drug curcumin (Cur). The enhanced Cur solubility is well-established from the distinctive peak intensities as observed from UV–Visible (UV–vis) and Fourier Transform Infrared (FT-IR) spectral profile which validated the interaction of Cur with the examined copolymeric systems.