Geometric control of inkjet printed features using a gelating polymer

Abstract

When an inkjet printed feature is formed, the behaviour of the ink on the substrate is of great importance. In order to investigate the possibility of increased control over the as-printed feature on a substrate, a TiO 2 ink was formulated that gels above a certain temperature. The TiO 2 particles in the ink are colloidally stabilised by an adsorbed layer of poly(vinyl methyl ether)block-poly(vinyloxy-4-butyric acid) diblock copolymer. The thermal gelation, at about 37 uC, is due to the limited solubility of the poly(vinyl methyl ether) buoyant block in the continuous medium of the ink. Drops and lines with improved morphological control and resolution were achieved using the thermal gelation effect. Lines printed using this approach did not display deviations at their starts and ends; and bulges in the line could be avoided. Finally, defect-free straight lines could be printed on very hydrophobic surfaces, which is impossible with regular inks due to the de-wetting nature of such substrates.

Inkjet Printing—Process and Its Applications

“…Use of thermally gelating polymers is one method that can help ensure this outcome. Printing of continuous polymer lines using gelating polymers has been demonstrated by van den Berg et al [14] The authors used a diblock copolymer poly(vinyl methyl ether)-block-poly(vinyloxy-4-butyric acid) colloidally stabilizing a TiO 2 ink. Thermally gelating materials exhibit strong temperature dependence.…”

Inkjet Printing of Narrow Conductive Tracks on Untreated Polymeric Substrates

“…Preferably, the surface energy should not be too low, because printing on such foils introduces bulges into the printed features, [25,26] for example with poly(tetrafluorethylene) (PTFE) foils. Line-bulging is an unwanted mechanism that locally broadens the printed structures, as can be seen on the left-hand side of Figure 1.…”

Integration of additive manufacturing and inkjet printed electronics: a potential route to parts with embedded multifunctionality

“…A final morphology observed in printed lines is that of ''bulging'' [68,88,89,104,106]. This was first observed by Duineveld [88], and was explained due to the relative driving forces for flow of newly deposited droplets.…”

“…The impingement process should dissipate any excess energy of the droplet upon impact and reach an energetically stable state with both the substrate and any other droplets previous deposited within the locale. The phase change typically takes the form of evaporation of carrier solvent [38-40, 44, 54, 60, 67], although can also be via solidification [47,51,56], or gelation [68,69]. Depending upon the ink system used, it may subsequently be necessary to perform further processing to achieve the desired functionality, such as thermal treatment [44,[70][71][72], electromagnetic irradiation [73][74][75], or chemical treatment [76][77][78][79][80][81].…”