Coalescence of sessile polymer droplets: A molecular dynamics study

TL;DR

This study uses molecular dynamics simulations to analyze how polymer droplet coalescence on substrates depends on wettability and polymer chain length, revealing key factors affecting coalescence dynamics.

Contribution

It provides new insights into the effects of substrate wettability and polymer chain length on droplet coalescence dynamics through detailed molecular simulations.

Findings

Smaller contact angles lead to faster bridge growth.

Increasing polymer chain length slows down coalescence.

Substrate wettability influences approach dynamics more than chain length.

Abstract

Droplet coalescence is ubiquitous in nature and the same time key to various technologies, such as inkjet printing. Here, we report on the coalescence of polymer droplets with different chain lengths coalescing on substrates of different wettability. By means of molecular dynamics simulations of a coarse-grained model, it is found that the rate of bridge growth is higher in the case of droplets with smaller contact angles (more wettable substrates) and decreases with the increase of the chain length of the polymers. Different behavior has also been identified in the dynamics of the approach of the two droplets during coalescence with the substrate wettability playing a more important role compared to the chain length of the polymers. While the dynamics of the droplet are greatly affected by the latter parameters, the density profile and flow patterns remain the same for the different cases. Thus, we anticipate that our work provides further insights into the coalescence of liquid polymer droplets on solid substrates with implications for relevant technologies.