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Correction: Foroozani Behbahani, A.; Harmandaris, V. Gradient of Segmental Dynamics in Stereoregular Poly(methyl methacrylate) Melts Confined between Pristine or Oxidized Graphene Sheets. Polymers 2021, 13, 830
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Correction published on 29 December 2021, see Polymers 2022, 14(1), 106.
Article

Gradient of Segmental Dynamics in Stereoregular Poly(methyl methacrylate) Melts Confined between Pristine or Oxidized Graphene Sheets

1
Institute of Applied and Computational Mathematics, Foundation for Research and Technology-Hellas, GR-71110 Heraklion, Greece
2
Department of Mathematics and Applied Mathematics, University of Crete, GR-70013 Heraklion, Greece
3
Computation-Based Science and Technology Research Center, The Cyprus Institute, 2121 Nicosia, Cyprus
*
Authors to whom correspondence should be addressed.
Academic Editors: Jens-Uwe Sommer and Martin Kröger
Polymers 2021, 13(5), 830; https://doi.org/10.3390/polym13050830
Received: 4 February 2021 / Revised: 27 February 2021 / Accepted: 2 March 2021 / Published: 8 March 2021 / Corrected: 29 December 2021
(This article belongs to the Special Issue Theory of Polymers at Interfaces)
Segmental dynamics in unentangled isotactic, syndiotactic, and atactic poly(methyl methacrylate) (i-, a-, and s-PMMA) melts confined between pristine graphene, reduced graphene oxide, RGO, or graphene oxide, GO, sheets is studied at various temperatures, well above glass transition temperature, via atomistic molecular dynamics simulations. The model RGO and GO sheets have different degrees of oxidization. The segmental dynamics is studied through the analysis of backbone torsional motions. In the vicinity of the model nanosheets (distances less than ≈2 nm), the dynamics slows down; the effect becomes significantly stronger with increasing the concentration of the surface functional groups, and hence increasing polymer/surface specific interactions. Upon decreasing temperature, the ratios of the interfacial segmental relaxation times to the respective bulk relaxation times increase, revealing the stronger temperature dependence of the interfacial segmental dynamics relative to the bulk dynamics. This heterogeneity in temperature dependence leads to the shortcoming of the time-temperature superposition principle for describing the segmental dynamics of the model confined melts. The alteration of the segmental dynamics at different distances, d, from the surfaces is described by a temperature shift, ΔTseg(d) (roughly speaking, shift of a characteristic temperature). Next, to a given nanosheet, i-PMMA has a larger value of ΔTseg than a-PMMA and s-PMMA. This trend correlates with the better interfacial packing and longer trains of i-PMMA chains. The backbone torsional autocorrelation functions are shown in the frequency domain and are qualitatively compared to the experimental dielectric loss spectra for the segmental α-relaxation in polymer nanocomposites. The εT(f) (analogous of dielectric loss, ε(f), for torsional motion) curves of the model confined melts are broader (toward lower frequencies) and have lower amplitudes relative to the corresponding bulk curves; however, the peak frequencies of the εT(f) curves are only slightly affected. View Full-Text
Keywords: segmental dynamics; α-relaxation; confinement; interfaces; poly(methyl methacrylate); tacticity; graphene; graphene oxide; surface–chemistry; simulations segmental dynamics; α-relaxation; confinement; interfaces; poly(methyl methacrylate); tacticity; graphene; graphene oxide; surface–chemistry; simulations
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MDPI and ACS Style

Foroozani Behbahani, A.; Harmandaris, V. Gradient of Segmental Dynamics in Stereoregular Poly(methyl methacrylate) Melts Confined between Pristine or Oxidized Graphene Sheets. Polymers 2021, 13, 830. https://doi.org/10.3390/polym13050830

AMA Style

Foroozani Behbahani A, Harmandaris V. Gradient of Segmental Dynamics in Stereoregular Poly(methyl methacrylate) Melts Confined between Pristine or Oxidized Graphene Sheets. Polymers. 2021; 13(5):830. https://doi.org/10.3390/polym13050830

Chicago/Turabian Style

Foroozani Behbahani, Alireza, and Vagelis Harmandaris. 2021. "Gradient of Segmental Dynamics in Stereoregular Poly(methyl methacrylate) Melts Confined between Pristine or Oxidized Graphene Sheets" Polymers 13, no. 5: 830. https://doi.org/10.3390/polym13050830

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