Lipophilic Diol Induced Micellization of Pluronic® F88 in Water

Abstract

The presence of a lipophilic S104 (also known as C14diol) induces micellization in a highly hydrophilic ethylene oxide–propylene oxide–ethylene oxide triblock copolymer Pluronic® F88 [(EO)103(PO)39–(EO)103] in water. The dynamic light scattering (DLS) and small angle neutron scattering (SANS) reveal that F88 remains as molecularly dissolved at ambient temperature even at fairly high concentrations (5 wt% or more). However, the micellization is induced at lower concentration/temperature in the presence of S104. The scattering measurements indicated micellar growth, though no phase transition was observed. The addition of hydrophobic S104 increases the aggregation numbers of the micellar system, but does not show a considerable increase in hydrodynamic size. The micellar parameters for the copolymer in the presence of S104 are reported at 30 and 40°C. Hydrophobic S104 interacts with PPO blocks of F88, makes the decreasing CMT of F88, which may be the synergistic effect. Using intermolecular rotating-frame nuclear overhauser effect (ROE) profiles, the interactions between PPO methyl and S104 terminal methyl groups can be obviously observed.