(84c) Polyethylene Oxide (PEO) in a Polyethylene (PE) Framework: A Simple Model for Simulation Studies of Scaling and Solvent Effects on Polymers in an Open Framework

We report molecular dynamics simulations studies of a polyethylene oxide polymer in a cubic polyethylene framework. Radius of gyration, shape, and other structural parameters are computed. Self-diffusion and displacement relative to the framework are also computed to investigate mobility and transport behavior. To investigate scaling effects, polyethylene oxide polymers of three different lengths and framework of three different sizes are simulated. Explicit water molecules are introduced to investigate solvation effects in different dimensions of polymer and framework.

Confinement of the polymer in smaller framework lead to closer interactin of polymer and framework and a more elongated configuration. The elongated configuration is favorable for diffusion through small windows of the framework. A larger mean square displacement is observed for the smaller framework, particularly in the presence of water. Adjusting the framework interaction potential sees a critical threshold dividing normal diffusion behavivoir and a regime dominated by hopping between cavities of the framework.

Although the model framework contains only simple van der Waalsl groups, confinement and solvent effects on polymer observed agree qualitatively with those in experiments reported recently for polyeletrolyte threaded in metal organic frameworks [1,2]

[1] L. Gao, C.Y.V. Li, and K.Y. Chan, Chem. Mater. 27(10) (2015) 3601-3608.

[2] L. Gao, C.Y. V. Li, K.Y. Chan, and Z.N. Chen, J. Am. Chem. Soc. 136 (2014) 7209-7212.