Temperature dependence of polymer network diffusion
Takeshi Fujiyabu, Takamasa Sakai, Ryota Kudo, Yuki Yoshikawa, Takuya Katashima, Ung-il Chung, and Naoyuki Sakumichi
The swelling dynamics of polymer gels are characterized by the (collective) diffusion coefficient D of the polymer network. Here, we measure the temperature dependence of D of polymer gels with controlled homogeneous network structures using dynamic light scattering. An evaluation of the diffusion coefficient at the gelation point Dgel and the increase therein as the gelation proceeds ΔD≡D−Dgel indicates that ΔD is a linear function of the absolute temperature with a significantly large negative constant term. This feature is formally identical to the recently discovered "negative energy elasticity’’ [Phys. Rev. X 11, 011045 (2021)], demonstrating a nontrivial similarity between the statics and dynamics of polymer networks.
Physical Review Letters : https://journals.aps.org/prl/accepted/1e07bY75S661258cf6495802dd3daac1c85b89a84