Thin, binary liquid droplets, containing polymer: An investigation of the parameters controlling film shape

Accepted version
Repository DOI

Type
Article
Change log
Authors
Eales, AD 
Dartnell, N 
Goddard, S 
Routh, AF 
Abstract

jats:pFor the fabrication of P-OLED displays, using inkjet printing, it is important to control the final shape resulting from evaporation of droplets containing polymer. Due to peripheral pinning and consequent outward capillary flow, a ring-like final shape is typically observed. This is often undesirable, with a spatially uniform film usually required. Several experimental studies have shown that binary liquid inks can prevent ring formation. There is no consensus of opinion on the mechanism behind this improvement. We have developed a model for the drying of thin, binary liquid droplets, based on thin-film lubrication theory, and we solve the governing equations to predict the final shape. White-light interferometry experiments are conducted to verify the findings. In addition, we present the results of a linear stability analysis that identifies the onset of an instability driven by a difference in surface tension. If the more volatile liquid is more abundant, an instability becomes increasingly likely.</jats:p>

Description
Keywords
capillary flows, colloids, thin films
Journal Title
Journal of Fluid Mechanics
Conference Name
Journal ISSN
0022-1120
1469-7645
Volume Title
794
Publisher
Cambridge University Press (CUP)
Sponsorship
This research has been funded by the Engineering & Physical Sciences Research Council, UK and CASE studentship funding from Cambridge Display Technology Ltd., UK. We thank Dr Mark Dowling of Cambridge Display Technology Ltd., for help with the experimental setup.