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Abstract
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| Rod-coil block copolymers have attracted a lot of interest in the last decade for their potential use in organic electronics and biomaterial applications. The equilibrium self-assembly of these materials has been thoroughly investigated, but a fundamental understanding of their dynamics is still not complete. Previous theoretical and experimental results suggest the appearance of new mechanisms of diffusion that slow down the dynamics of rod-coil diblock and triblock copolymers, with diffusivities that are smaller than both rod and coil homopolymers by over an order of magnitude in some cases. As a result, a modified reptation theory has been introduced that attributes the slow dynamics of rod-coils to the mismatch between the curvatures of the entanglement tubes of the rod and coil blocks [8]. The present work extends the theoretical and simulation study to the case where both molecular ends are occupied by rods. In this new configuration, arm retraction is not and activated reptation is extremely difficult because any motion of the chain along its tube needs to drag both end rods along the flexible tube corresponding to the coil block. In addition, any new tube segment must be stiff, and therefore, in the absence of constraint release, the whole tube must have a very small curvature. New relaxation mechanisms emerge that result in even slower relaxation dynamics than in the case of similar rod-coil and coil-rod-coil block copolymers. A linear polymer that takes such a long time to disentangle is expected to also entangle at a very slow pace. From a technological point of view, a material with such slow reentanglement dynamics would be of interest in itself, because it would show a very low steady state viscosity. Knowledge of the mechanisms of motion and relaxation of these materials is of utmost importance for the prediction of their flow properties, their kinetics of self-assembly, and for the design of the right manufacturing processes. | |
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International
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Si |
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Congress
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IBEREO 2017 |
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960 |
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Place
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Valencia, España |
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Reviewers
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Si |
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ISBN/ISSN
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978-84-697-5123-7 |
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Start Date
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06/09/2017 |
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End Date
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08/09/2017 |
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From page
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214 |
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To page
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217 |
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The multidisciplinary science of Rheology - Towards a healthy and sustainable development |