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Anomalous diffusion of polystyrene from an attractive substrate based on all-atom simulation

Abstract

The diffusion of polystyrene (PS) polymer chains from hydroxy (-OH)-terminated Si surface with different grafting densities $\phi_G$, is studied based on all-atom simulation. Our particular attention is paid to the impact of the attractive substrate to the diffusive and conformational properties of PS. Our simulation results uncovered a very novel and unexpected modification to polymer diffusion with the increment of $\phi_G$, namely, the diffusion is slowed down most significantly from a substrate with moderate grafting densities, while in lower or full grafting cases, the diffusive dynamics is even facilitated rather than retarded. The underlying mechanism is investigated in terms of energy and conformational change in detail. Surprisingly, we obtain a consistent scenario to diffusion. Under moderate grafting densities, the energy required to be overcome for diffusion is relatively large. In addition, PS chains are more likely to be a stretched conformation subject to a slower relaxation. These facts can account for the hindered diffusion. While under lower or full grafting densities, the diffusion required energy becomes even smaller than the ungrafted situation. Also, PS chains prefer a shrinking conformation undergoing faster relaxation. Consequently, the diffusion of PS is reasonably promoted.

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Publication details

The article was received on 02 Jul 2018, accepted on 10 Sep 2018 and first published on 11 Sep 2018


Article type: Paper
DOI: 10.1039/C8CP04177F
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Anomalous diffusion of polystyrene from an attractive substrate based on all-atom simulation

    B. Zhang, X. Cao, G. Zhou and N. Zhao, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP04177F

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