Smart polymer solution and thermal conductivity: How important is an exact polymer conformation?

Fuente: arXiv
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Hauptverfasser: Chowdhury, Mokter M., Cortes-Huerto, Robinson, Mukherji, Debashish
Format: Preprint
Veröffentlicht: 2024
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author Chowdhury, Mokter M.
Cortes-Huerto, Robinson
Mukherji, Debashish
author_facet Chowdhury, Mokter M.
Cortes-Huerto, Robinson
Mukherji, Debashish
contents Heat management in devices is a key to their efficiency and longevity. Here, thermal switches (TS) are of great importance because of their ability to transition between different thermal conductivity $κ$ states. While traditional TS are bulky and slow, recent experiments have suggested "smart" responsive (bio--inspired) polymers as their fast alternatives. One example is poly(N--isopropylacrylamide) (PNIPAM) in water, where $κ$ drops suddenly around a temperature $T_{\ell} \simeq 305$ K when a PNIPAM undergoes a coil--to--globule transition. At a first glance, this may suggest that the change in polymer conformation has a direct influence on TS. However, it may be presumptuous to trivially "only" link conformations with TS, especially because many complex microscopic details control macroscopic conformational transition. Motivated by this, we study TS in "smart" polymers using generic simulations. As the test cases, we investigate two different modes of polymer collapse using external stimuli, i.e., changing $T$ and cosolvent mole fraction $x_{\rm c}$. Collapse upon increasing $T$ shows a direct correlation between the conformation and $κ$ switching, while no correlation is observed in the latter case. These results suggest that the (co--)solvent--monomer interactions play a greater important role than the exact conformation in dictating TS. While some results are compared with the available experiments, possible future directions are also highlighted.
format Preprint
id arxiv_https___arxiv_org_abs_2407_13063
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Smart polymer solution and thermal conductivity: How important is an exact polymer conformation?
Chowdhury, Mokter M.
Cortes-Huerto, Robinson
Mukherji, Debashish
Soft Condensed Matter
Mesoscale and Nanoscale Physics
Materials Science
Heat management in devices is a key to their efficiency and longevity. Here, thermal switches (TS) are of great importance because of their ability to transition between different thermal conductivity $κ$ states. While traditional TS are bulky and slow, recent experiments have suggested "smart" responsive (bio--inspired) polymers as their fast alternatives. One example is poly(N--isopropylacrylamide) (PNIPAM) in water, where $κ$ drops suddenly around a temperature $T_{\ell} \simeq 305$ K when a PNIPAM undergoes a coil--to--globule transition. At a first glance, this may suggest that the change in polymer conformation has a direct influence on TS. However, it may be presumptuous to trivially "only" link conformations with TS, especially because many complex microscopic details control macroscopic conformational transition. Motivated by this, we study TS in "smart" polymers using generic simulations. As the test cases, we investigate two different modes of polymer collapse using external stimuli, i.e., changing $T$ and cosolvent mole fraction $x_{\rm c}$. Collapse upon increasing $T$ shows a direct correlation between the conformation and $κ$ switching, while no correlation is observed in the latter case. These results suggest that the (co--)solvent--monomer interactions play a greater important role than the exact conformation in dictating TS. While some results are compared with the available experiments, possible future directions are also highlighted.
title Smart polymer solution and thermal conductivity: How important is an exact polymer conformation?
topic Soft Condensed Matter
Mesoscale and Nanoscale Physics
Materials Science
url https://arxiv.org/abs/2407.13063