Effect of molecular weight on polymer solution facilitated transfer of non-Brownian particles

Abstract

Solution driven particle transfer on solid substrates has many industrial applications but can be difficult to control and characterize. In this study, poly(methyl methacrylate) (PMMA) is considered as the binder polymer, and the effect of the molecular weight (MW) on particle transfer through entrainment is investigated. The transfer phenomenon of polydisperse spherical rigid micro-particles from the PMMA solution has been analyzed and two hypotheses are tested here: (i) there exists a threshold polymer content below which only the smallest particles will be transferred from the bulk; (ii) at the same viscosity of different molecular weight PMMA solution, the solid transfer phenomenon will be similar. By changing the mass and viscosity using three PMMA samples with different MWs in the 1,3-dioxolane solvent, we observe low, intermediate, and high viscous regimes of the PMMA-dioxolane solution system. The low, intermediate, and high viscous regimes can be controlled with the MW and can entrain distinct particle size distributions onto surfaces. This behavior is thoroughly analyzed and relates to the film formation. These results confirmed our first hypothesis that we could use polymer content to control the particle size distribution and that a threshold polymer content exists. However, at similar viscosities, higher molecular weight polymers yielded lower average particle sizes and narrower distributions, which is counter to our second hypothesis. These findings can provide a better understanding of the binder behavior and its influence on the particle transfer process which opens-up the possibility of particle sorting process from a polydisperse suspension mixture and high-yield material transfer for porous structure coating and joining processes. Understanding the particle transfer process can also enable reverse engineering of the liquid carrier system in a complex mixture, which can be beneficial for industrial applications.