Synthesis and Characterization of Amphiphilic Hairy Nanoparticles with pH and Ionic Dual‐Responsiveness

Abstract

Recently, polymeric shell hybrid nanoparticles with multiresponse to external triggers have attracted much interests in academic researches and technical industries. This work provided a novel of amphiphilic hairy nanoparticles (APNPs) with distinct pH and ionic dual‐responsiveness based on silica nanoparticles as the core, amphiphilic‐polymeric chains containing amine‐moieties, and carboxylic groups as the layer by a facile emulsion polymerization. The structural parameters of APNPs were characterized by combining thermal gravimetric analysis, infrared spectroscopy, proton nuclear magnetic resonance, transmission electronic microscopy, and dynamic light scattering. The polymeric shell in water was compressed due to proton‐transference from carboxylic groups to amine‐moieties, where APNPs behaved as colloidal particles. By adding HCl, carboxyl groups were deionized, whereas the electrostatic repulsion of protonated amine‐moieties between the neighboring chains expanded the polymeric shell, and thus APNPs self‐assembled into a typical viscoelastic fluid. APNPs reconstructed into branch‐like viscoelastic gel in the presence of cationic ions under alkaline environment. Such transformation was reversible by adjusting the pH of APNPs dispersion. APNPs might have potential application in enhanced oil recovery of unconventional reservoirs because of their original low viscosity for desirable injectivity from ground to micro‐nanopores of subsurface, and the dramatic increase in viscosity for mobility control triggered by pH and ionic ions. POLYM. ENG. SCI., 60:563–574, 2020. © 2019 Society of Plastics Engineers