Predictive Mastercurves for Direct Ink Writing: Application to Sustainable and Piezoelectric PLA‐Anisole Inks

ABSTRACT

Direct ink writing represents a straightforward printing technique for functional inks. Predicting their behavior is of prime importance to optimize ink formulations for high‐quality printed designs. DIW behaviors of sustainable and Newtonian PLA‐anisole inks are here investigated along with piezoelectric inks based on barium titanate microparticles. Flow rates in printing needles were controlled by printing pressure, needle diameter, and viscosity. The importance of capillary forces is pointed out for their deposition on flexible substrates. Geometries of printed tracks were analyzed depending on printing pressure and speed. Ink viscosities played a major role, and PI/PET are ideal substrates due to excellent wetting, ensuring continuous tracks with a high regularity even at elevated speeds. All printing data from various inks and substrates successfully collapsed onto a single scaling law by integrating a substrate‐specific wetting factor coupled with reduced parameters. The final resolution is consequently governed by mass conservation and wettability. The DIW mastercurve efficiently predicts printing pitches for optimal production of high‐quality surfaces. Successful transposition to piezoelectric inks was attested, and piezoelectric surfaces exhibited competitive performances compared to cast films. This framework consequently offers rational guidelines for functional ink formulation and optimal DIW printing on many flexible substrates.