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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 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 drops suddenly around a temperature T_ 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 ₂. Collapse upon increasing T shows a direct correlation between the conformation and 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.
Chowdhury et al. (Tue,) studied this question.