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Article

Dynamic Heterogeneity in Ring-Linear Polymer Blends

1
Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
2
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
3
Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras, Greece
4
Particle Technology Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, CH-8092 Zürich, Switzerland
*
Authors to whom correspondence should be addressed.
Polymers 2020, 12(4), 752; https://doi.org/10.3390/polym12040752
Received: 7 February 2020 / Revised: 15 March 2020 / Accepted: 18 March 2020 / Published: 30 March 2020
(This article belongs to the Section Polymer Physics and Theory)
We present results from a direct statistical analysis of long molecular dynamics (MD) trajectories for the orientational relaxation of individual ring molecules in blends with equivalent linear chains. Our analysis reveals a very broad distribution of ring relaxation times whose width increases with increasing ring/linear molecular length and increasing concentration of the blend in linear chains. Dynamic heterogeneity is also observed in the pure ring melts but to a lesser extent. The enhanced degree of dynamic heterogeneity in the blends arises from the substantial increase in the intrinsic timescales of a large subpopulation of ring molecules due to their involvement in strong threading events with a certain population of the linear chains present in the blend. Our analysis suggests that the relaxation dynamics of the rings are controlled by the different states of their threading by linear chains. Unthreaded or singly-threaded rings exhibit terminal relaxation very similar to that in their own melt, but multiply-threaded rings relax much slower due to the long lifetimes of the corresponding topological interactions. By further analyzing the MD data for ring molecule terminal relaxation in terms of the sum of simple exponential functions we have been able to quantify the characteristic relaxation times of the corresponding mechanisms contributing to ring relaxation both in their pure melts and in the blends, and their relative importance. The extra contribution due to ring-linear threadings in the blends becomes immediately apparent through such an analysis. View Full-Text
Keywords: dynamic heterogeneity; rings; threading events dynamic heterogeneity; rings; threading events
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MDPI and ACS Style

Katsarou, A.F.; Tsamopoulos, A.J.; Tsalikis, D.G.; Mavrantzas, V.G. Dynamic Heterogeneity in Ring-Linear Polymer Blends. Polymers 2020, 12, 752. https://doi.org/10.3390/polym12040752

AMA Style

Katsarou AF, Tsamopoulos AJ, Tsalikis DG, Mavrantzas VG. Dynamic Heterogeneity in Ring-Linear Polymer Blends. Polymers. 2020; 12(4):752. https://doi.org/10.3390/polym12040752

Chicago/Turabian Style

Katsarou, Anna F.; Tsamopoulos, Alexandros J.; Tsalikis, Dimitrios G.; Mavrantzas, Vlasis G. 2020. "Dynamic Heterogeneity in Ring-Linear Polymer Blends" Polymers 12, no. 4: 752. https://doi.org/10.3390/polym12040752

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