A Generalized Rouse Incoherent Scattering Function for Chain Dynamics of Unentangled Polymers in Dynamically Asymmetric Blends

The chain dynamics of unentangled polymers strongly deviates from the expected Rouse behavior when they form part of dynamically asymmetric polymer blends. These are miscible systems where the two components display very different segmental mobility (or glass transition). The generalized Langevin eq...

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Bibliographic Details
Published in:Macromolecules 2013-07, Vol.46 (13), p.5363-5370
Main Author: Colmenero, J
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Organic polymers
Physicochemistry of polymers
Properties and characterization
Rheology and viscoelasticity
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Summary:The chain dynamics of unentangled polymers strongly deviates from the expected Rouse behavior when they form part of dynamically asymmetric polymer blends. These are miscible systems where the two components display very different segmental mobility (or glass transition). The generalized Langevin equation formalism seems to be a suitable theoretical framework for this situation. In this work, we have used an approximation based on (i) a simplified generalized Langevin equation and (ii) the phenomenological result of nonexponential decay of the Rouse model correlators in asymmetric polymer blends. In the framework of this approximation, we have deduced an incoherent scattering function for chain dynamics of unentangled polymers in asymmetric blends. This functionwhich in the Rouse limit reduces to the well-known de Gennes expressionis validated by molecular dynamics simulation results of a canonical asymmetric blend: poly(methyl methacrylate)/poly(ethylene oxide).
ISSN:0024-9297
1520-5835
DOI:10.1021/ma400309c