Interface relaxation in electrophoretic deposition of polymer chains: Effects of segmental dynamics, molecular weight, and field

TL;DR

This study uses Monte Carlo simulations to explore how segmental dynamics, molecular weight, and electric field influence interface relaxation during electrophoretic polymer deposition, revealing key scaling behaviors and relaxation mechanisms.

Contribution

It demonstrates the importance of including various segmental movements in modeling interface relaxation and characterizes the effects of molecular weight and field on interface width.

Findings

Interface width grows as a power law with time before saturating.

Relaxation after stopping chain release reduces the interface width.

Relaxed interface width scales inversely with the square root of the field.

Abstract

Using different segmental dynamics and relaxation, characteristics of the interface growth is examined in an electrophoretic deposition of polymer chains on a three (2+1) dimensional discrete lattice with a Monte Carlo simulation. Incorporation of faster modes such as crankshaft and reptation movements along with the relatively slow kink-jump dynamics seems crucial in relaxing the interface width. As the continuously released polymer chains are driven (via segmental movements) and deposited, the interface width $W$ grows with the number of time steps $t$, $W \propto t^{\beta},$ ($\beta \sim 0.4$--$0.8)$, which is followed by its saturation to a steady-state value $W_s$. Stopping the release of additional chains after saturation while continuing the segmental movements relaxes the saturated width to an equilibrium value ($W_s \to W_r$). Scaling of the relaxed interface width $W_r$ with the driving field $E$, $W_r \propto E^{-1/2}$ remains similar to that of the steady-state $W_s$ width. In contrast to monotonic increase of the steady-state width $W_s$, the relaxed interface width $W_r$ is found to decay (possibly as a stretched exponential) with the molecular weight.