Tribological properties of flexible composite surfaces through direct ink writing for durable wearing devices

Polydimethylsiloxane (PDMS), as a polymer material with excellent mechanical properties and flexibility, is widely used in flexible wearable devices, soft robots and other fields. Commonly, the Mold-flipping is used to produce PDMS based samples, while it is time-consuming and impractical for the large-scale fabrication. With the additive manufacturing, printing pastes can be freely configured thanks to direct ink writing (DIW) technology, enabling rapid and high precision manufacturing. Herein, we have improved the rheology of Sylgard-184 by adding crosslinkers and silica nanoparticles to make it printable. By adjusting the printing path, flexible surfaces with textures were created. Ball-on-disc dry friction experiments were carried out on the specimens. Results show that the texture produced by the print path can effectively reduce the coefficient of friction (COF) compared to samples produced by the conventional molding. When the print path is at 60° to the sliding direction, COFs for samples are reduced by 23.2% to 32.9%. Our findings provide a new strategy for preparing flexible and wearable devices through significantly enhancing the wear resistance of substantiable usage and prolonging the lifespan.