We present molecular dynamics simulations of a polymer monolayer on randomly functionalized surfaces that are characterized by different fractions of weakly and strongly attractive sites. We show that the dynamics slow-down upon cooling resembles that of a strong glass-forming liquid. Indeed, the mean-square displacements show an increasingly lasting subdiffusive behaviour before the diffusive regime, with signs of Fickian yet not Gaussian diffusion, and the dynamic correlation functions exhibit a stretched exponential decay. The glassy dynamics of this relatively dilute system is dominated by the interaction of the polymer with the substrate and becomes more marked when the substrate composition is heterogeneous. Accordingly, the estimated glass transition temperature shows a non-monotic dependence on surface composition, in agreement with previous results for the activation energy and with an analysis of the potential energy landscape experienced by the polymer beads. Our findings are relevant to the description of polymer–surface adhesion and friction and the development of polymer nanocomposites with tailored structural and mechanical properties.

Glassy dynamics of a polymer monolayer on a heterogeneous disordered substrate / Pastore, Raffaele; Raos, Guido. - In: SOFT MATTER. - ISSN 1744-683X. - 11:41(2015), pp. 8083-8091. [10.1039/c5sm01440a]

Glassy dynamics of a polymer monolayer on a heterogeneous disordered substrate

PASTORE, RAFFAELE
;
2015

Abstract

We present molecular dynamics simulations of a polymer monolayer on randomly functionalized surfaces that are characterized by different fractions of weakly and strongly attractive sites. We show that the dynamics slow-down upon cooling resembles that of a strong glass-forming liquid. Indeed, the mean-square displacements show an increasingly lasting subdiffusive behaviour before the diffusive regime, with signs of Fickian yet not Gaussian diffusion, and the dynamic correlation functions exhibit a stretched exponential decay. The glassy dynamics of this relatively dilute system is dominated by the interaction of the polymer with the substrate and becomes more marked when the substrate composition is heterogeneous. Accordingly, the estimated glass transition temperature shows a non-monotic dependence on surface composition, in agreement with previous results for the activation energy and with an analysis of the potential energy landscape experienced by the polymer beads. Our findings are relevant to the description of polymer–surface adhesion and friction and the development of polymer nanocomposites with tailored structural and mechanical properties.
2015
Glassy dynamics of a polymer monolayer on a heterogeneous disordered substrate / Pastore, Raffaele; Raos, Guido. - In: SOFT MATTER. - ISSN 1744-683X. - 11:41(2015), pp. 8083-8091. [10.1039/c5sm01440a]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/717777
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