Particulate Coacervation of Associative Polymer Brushes-Grafted Nanoparticles To Produce Structurally Stable Pickering Emulsions

Abstract

This study introduces a new type of associative nanoparticle (ANP) that provides controlled chain-to-chain attraction with an associative polymer rheology modifier (APRM) to produce highly stable Pickering emulsions. The ANPs were synthesized by grafting hydrophobically modified hygroscopic zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine-co-stearyl methacrylate) brushes onto 20 nm sized silica NPs via surface-mediated living radical polymerization. The ANP-stabilized Pickering emulsions show significant viscosity enhancement in the presence of the APRM. This indicates that the ANPs act as particulate concentration agents at the interface owing to their hydrophobic association with the APRM in the aqueous phase, which leads to the generation of an ANP-mediated complex colloidal film. Consequently, the described ANP-reinforced Pickering emulsion system exhibits improved resistance to pH and salinity changes. This coacervation approach is advantageous because the complex colloidal layer at the interface provides the emulsion drops with a mechanically robust barrier, thus guaranteeing the improved Pickering emulsion stability against harsh environmental factors.

Oil–Water Interfacial-Directed Spontaneous Self-Assembly of Natural Quillaja Saponin for Controlling Interface Permeability in Colloidal Emulsions

“…It is therefore reasonable to conclude that QS likely self-assembles at the oil–water interface resulting in a multilayer surface onto the emulsion droplets. This action is critical for producing an elastic film to enhance the emulsion interface improving the emulsion stability …”

Magnetic-Patchy Janus Colloid Surfactants for Reversible Recovery of Pickering Emulsions

“…Their assembly at the water−oil interface was directly verified by using JMPs tagged with a fluorescent probe (Figures 6A and S7). 31 Because the JMPs had the designated amphiphilicity, which is determined by the degree of Janusity, each bulb of JMPs was wet by the compatible liquid phase: the hydrophilic magnetic-patchy bulb by the water phase and the hydrophobic PTA bulb by the oil phase (Figure 6B,C). The contact angle of the magnetic-patchy JMPs at the oil−water interface decreased from 127°to 90°with an increasing degree of Janusity.…”

Microfluidic production of monodisperse emulsions for cosmetics

“…If a stable emulsion can be prepared without using a surfactant, both environmental and skin safety issues can be resolved. For this purpose, a variety of types of colloidal particles such as silica, 58,59 clay, 60,61 polymeric particles, 62,63 and organic fibrous materials 64,65 can be considered emulsifiers for emulsion stabilization. Although such materials are effective for solidifying the emulsion interface with a monolayer, interfacial coverage cannot be perfect because of the generation of interstitial defects due to the geometry of the particles.…”