Emulsions stabilized by highly hydrophilic TiO<sub>2</sub> nanoparticles via van der Waals attraction

Hypothesis: Highly hydrophilic nanoparticles are generally considered not suitable for stabilizing Pickering emulsions, since they could not be effectively wetted by the oil phase at the water-oil interface. However, highly hydrophilic nanoparticles with good dispersity are possibly absorbed and packed onto the surface of the oil droplets in water via the van der Waals attraction between the nanoparticles and the oil droplets. Hence, a novel “van der Waals emulsion” should be possible to be stabilized by highly hydrophilic nanoparticles. Experiments: Oil-in-water emulsions solely stabilized by pristine TiO2 nanoparticles (i.e., TiO2 without any modification or additives) were prepared. The emulsification behavior under varying pH value, oil fraction, particle content and temperature of the emulsion were explored. Composite wax-based beads which encapsulated chemical sunscreen and was coated by TiO2 nanoparticles, was also fabricated using the obtained emulsion as the templates. Findings: The emulsions displayed the highest stability near the isoelectric points of the TiO2 nanoparticles, which was attributed to the van der Waals attraction between TiO2 nanoparticles and oil droplets. Such mechanism was supported by a theoretical analysis based on calculation of the Hamaker constants and experimental evidences. Therefore, this work presents a simple, general and green method for preparing particle-stabilized emulsions.

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Work Title Emulsions stabilized by highly hydrophilic TiO<sub>2</sub> nanoparticles via van der Waals attraction
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Open Access
Creators
  1. Jing Wang
  2. Yajuan Sun
  3. Mingying Yu
  4. Xihua Lu
  5. Sridhar Komarneni
  6. Cheng Yang
License In Copyright (Rights Reserved)
Work Type Article
Publisher
  1. Journal of Colloid and Interface Science
Publication Date May 1, 2021
Publisher Identifier (DOI)
  1. https://doi.org/10.1016/j.jcis.2021.01.011
Deposited November 18, 2021

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  • Added Creator Jing Wang
  • Added Creator Yajuan Sun
  • Added Creator Mingying Yu
  • Added Creator Xihua Lu
  • Added Creator Sridhar Komarneni
  • Added Creator Cheng Yang
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