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Interfacial Adsorption of pH-Responsive Polymers and Nanoparticles


Using dissipative particle dynamics (DPD), we model the interfacial adsorption of pH-responsive polyelectrolytes and polyelectrolyte-grafted nanoparticles (PNPs) at a planar water-oil interface. The electrostatic interactions in the presence of the dielectric discontinuity across the interface are modeled by exploiting the Groot method, which uses an iterative method to solve the Poisson equation on a uniform grid with distributed charge. We reveal the effect of the pH and salinity of the aqueous solution and the length of polyelectrolyte on the adsorption behavior of weak polyelectrolytes. The adsorption kinetics is monitored via the trajectory of the center of mass of the polyelectrolyte in the direction normal to the interface. The residence time at the interface and pair correlation function between polyelectrolyte and oil are measured to quantitatively characterize adsorption. Similar to the weak polyelectrolytes, the influences of pH, salinity and grafted chain length on the adsorption of individual PNP are explored. Our results show that by grafting polyelectrolytes, the interfacial behavior of the nanoparticles can be tuned by the pH and salinity of the solution, which is dictated by the contact angle, pair correlation function between particle and oil, desorption energy, and particle morphology at the interface. We also observe that the electrostatic-driven variation in the interfacial activity and morphology of PNPs is not sensitive to the length of grafted polyelectrolytes.

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Publication details

The article was received on 30 Mar 2017, accepted on 05 Jun 2017 and first published on 07 Jun 2017

Article type: Paper
DOI: 10.1039/C7SM00637C
Citation: Soft Matter, 2017, Accepted Manuscript
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    Interfacial Adsorption of pH-Responsive Polymers and Nanoparticles

    S. Qin and X. Yong, Soft Matter, 2017, Accepted Manuscript , DOI: 10.1039/C7SM00637C

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