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Tunable Primary and Secondary Encapsulation of a Charged Nonspherical Nanoparticle: Insights from Brownian Dynamics Simulations

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journal contribution
posted on 18.01.2017, 00:00 by Houyang Chen, Eli Ruckenstein
Surface properties of encapsulated nanoparticles play a central role in colloidal stability and in diverse applications of colloidal nanomaterials. In this paper, by employing Brownian dynamics simulations, we simulate the environment-dependent primary encapsulation of a charged nonspherical nanoparticle (NSNP) by Janus particles (JPs). We propose and determine, for the first time, the secondary encapsulation (i.e., reconfiguration of encapsulants on the surface of the NSNP), which also depends on the environment. The adsorption phase behavior and configuration transformation are strongly correlated with temperature and Bjerrum length. Bjerrum-length-induced order–order structural transitions and temperature-induced disorder–order/order–order structural transitions are found. Interestingly, electric double layers on the surfaces of the NSNP can form upon changing the environment. Our detailed results of primary encapsulation and secondary reconfiguration of encapsulants on the surface of the NSNP indicate that the surface properties of the charged NSNP are tunable and reversible. Such transformations should be readily detected experimentally by techniques such as zeta potential measurement. We also find that the primary encapsulation occurred via sequential adsorption and assembly of JPs, whereas the secondary encapsulation process involved adsorption/desorption of JPs and rotation of their configurations as well as their reassembly. These new insights may provide useful information in design and modulation of nanomaterials with surface properties that respond to their environment, for applications such as drug or gene delivery.

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