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Preparation of Janus Nanoparticles and Its Application in Oil Industry

Li, Wenhao
http://rave.ohiolink.edu/etdc/view?acc_num=akron1565799899860478

Abstract Details

2019, Master of Science in Polymer Engineering, University of Akron, Polymer Engineering.
Janus nanoparticles, named after the two-faced Roman god, possess anisotropic interfacial, chemical, and physical properties at their two different “faces”. Recently, Janus nanoparticles have received an increasing attention in the literature owing to their unique individual and collective properties. Such colloids have been used or considered to be utilized in the areas of emulsion stabilizers, viscosity modifiers, microreactors, photonic materials, and enhanced oil recovery. The main objective of this work is to develop new synthesis approaches for large-scale production of monodisperse Janus nanoparticles and to investigate the influence of hydrophilic-lipophilic balance, relative areas of anisotropic faces, and particle size on the phase behavior of oil-water-nanoparticle ternary mixtures as well as the colloidal stability of Janus particles themselves and their Pickering emulsions (oil-in-water emulsions stabilized by Janus nanoparticles). This work has mainly focused on precisely fabricating surface modified Janus nanoparticles based on a controlled sinking process. For this purpose, first, highly monodisperse spherical silica particles with diameters of 50 and 400 nm were synthesized through modified Stober method. The morphology and size of silica nanoparticles were characterized using Scanning Electron Microscope (SEM) and Dynamic Light Scattering (DLS) techniques. The zeta potential measurements revealed a surface charge of -40 to -45 mV for silica nanoparticles, indicating that the sufficient electrostatic surface charges were attained, giving rise to a fairly stable dispersion in aqueous solution. Highly ordered two-dimensional colloidal monolayers were attempted to be fabricated onto poly (methyl methacrylate) (PMMA) coated substrates using the Langmuir-Blodgett (LB) deposition technique. The pressure-area isotherms of silica nanoparticles at the air-water interface demonstrate a roughly linear-dependence between interfacial area (A) and surface pressure (π) up to ≈25 mN/m. Above this set point, surface pressure stayed constant with decreasing A, indicative of collapsing colloidal monolayers from the interface to the subphase. The hysteresis between expansion and compression isotherm cycles was found as a clear sign of the irreversible directed assembly processes. A well-ordered, packed monolayer of silica nanoparticles could be obtained at a surface-pressure of 10 mN/m as a result of attractive van der Waals interactions that could be promoted upon reaching below a critical interparticle separation. The exposed (unembedded) areas of the colloidal monolayers were carefully controlled by heating the PMMA matrix at predetermined temperatures and subsequently, modified by interfacially active ligands (e.g. chlorosilanes) through a chemical vapor deposition (CVD) method in order to achieve Janus characteristics. Contact angle measurements were also performed to qualify and quantify the wetting dynamics of Janus nanoparticles fabricated of which characteristics are found to be susceptible to ligand concentration as well as exposure time. Overall, it is anticipated that novel amphiphilic Janus nanoparticles fabricated through this study could significantly advance the current state-of-the-art in emulsion stability issues arising in many industrial processes including enhanced oil recovery.
Younjin Min (Advisor)
Sadhan C. Jana (Committee Member)
Thein Kyu (Committee Member)
67 p.
Polymers

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Citations

  • Li, W. (2019). Preparation of Janus Nanoparticles and Its Application in Oil Industry [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1565799899860478

    APA Style (7th edition)

  • Li, Wenhao. Preparation of Janus Nanoparticles and Its Application in Oil Industry. 2019. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1565799899860478.

    MLA Style (8th edition)

  • Li, Wenhao. "Preparation of Janus Nanoparticles and Its Application in Oil Industry." Master's thesis, University of Akron, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1565799899860478

    Chicago Manual of Style (17th edition)

akron1565799899860478
656
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This open access ETD is published by University of Akron and OhioLINK.