Temperature-responsive interdrop association of condensed attractive nanoemulsions

Abstract

This study introduces a temperature-responsive attractive nanoemulsion (ANE) system, which is characterized by the polymer chain conformation-driven dipolar interaction across different oil droplets in an aqueous medium. To achieve this, highly stable ANEs were produced by co-assembly of amphiphilic triblock copolymers (ATCs), poly(ethylene oxide)-b-poly(e-caprolactone)-b-poly(ethylene oxide) (PEO-b-PCL-b-PEO), with lecithin at the oil-water interface. The dipolar attraction of the methoxy terminated-PEO (mPEO) of ATCs on one drop surface with the lecithin head located on the other drop surface led to the drop-to-drop association. We showed that the efficiency of this interdrop association was dominantly influenced by the chain conformation of mPEO blocks. From dense suspension rheology studies, it was demonstrated that the ANEs formed a gel-like phase below the lower critical solution temperature (LCST) of the mPEO, but transformed to a liquid-like phase above the LCST, which occurred reversibly, thus enabling the development of temperature-responsive emulsion fluids. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.