Bond Stiffness, not Chain Length, Dictates Polymer Infiltration into Nanopores

TL;DR

This study reveals that polymer infiltration into nanopores is primarily governed by bond stiffness and segment size, not chain length, challenging previous assumptions and guiding nanostructure manufacturing.

Contribution

The paper demonstrates that the critical contact angle for polymer infiltration depends on segment size and bond stiffness, not chain length, supported by molecular dynamics simulations and a free energy model.

Findings

Critical contact angle is independent of chain length for large N.

Infiltration depends strongly on segment size and bond stiffness.

MD simulations confirm the theoretical model.

Abstract

We study the effect of physical confinement on the capillary infiltration of polymers into cylindrical nanopores using molecular dynamics simulations. In particular, we probe whether the critical contact angle above which capillary rise infiltration ceases to occur changes for long chain polymers, possibly due to loss of conformation entropy induced by chain confinement. Surprisingly, the critical contact angle does not strongly depend on the length of polymer chains and stays constant for large N. A free energy model is developed to show that the critical angle for infiltration depends strongly on the size of statistical segments rather than the total chain length, which we confirm by performing MD simulations of infiltration with semi-flexible polymers. These results could provide guidelines in manufacturing polymer nanostructures and nanocomposites using capillary rise infiltration.