Wettability of ink on paper is a key phenomenon underlying the inkjet printing process. The goal of this project is to establish a fast and reliable method to predict the degree of wettability of liquids on substrates.
We developed a method whereby the contact angle of a liquid droplet deposited on a substrate is extracted from simulations of the bulk liquid and the bulk substrate, without the two ever coming into contact in the simulations. The figure shows the excellent agreement between simulation results and experimental data. We also proposed a 3D wettability space, inspired by the Hansen solubility parameter space, to generate the wetting spheres of substrates, see Figure. This permits a fast prediction of the wettability properties of liquids and liquid mixtures on these substrates, facilitating the design of suitable inks for specific substrates.
a) Simulation-based versus experimental contact angle of several liquids on various polymeric substrates. PMMA: polymethyl methacrylate, PTFE: polytetrafluoroethylene, PP: polypropylene, PC: polycarbonate, PET: polyethylene terephthalate, POM: polyoxymethylene, PS: polystyrene and PVA: polyvinyl alcohol.
b) Wettability spheres with liquids, represented by dots, inside the blue (red) sphere forming contact angles of less than 15° (90°) on PTFE.