Optimization in 3D Printable Silicone DIW Ink Formulations: Gelling Behavior Control and the Use of Carbon Nanotubes

ABSTRACT In this study, a polydimethylsiloxane (PDMS)‐based particle‐filled two‐component reactive dispensable elastomeric ink was designed, formulated, and compounded to achieve balanced rheology and cure kinetics for high‐volume commercial direct ink writing (DIW) 3D printing. When mixed in equal proportions in situ before DIW printing, this ink gels rapidly via covalent crosslinking at ambient temperature. Subsequently, it undergoes progressive curing, transforming into a solid composite elastomer as it ascends toward the desired build height, with dimensional stability and no by‐products generated. This formulated DIW ink addresses several shortcomings inherent in existing elastomeric ink materials, thereby removing the barrier preventing the widespread adoption of DIW technology in commercial applications. Three modeling strategies were also performed to elucidate the structure–property relationship of this DIW ink: investigating the influence of percent inhibitor on the rate of crosslink gel formation to achieve flexibility in manufacturing operations; evaluating the impact of crosslinkers with increasing hydride content on gel time, cure hardness, and mechanical properties; and studying the potential effect of CNT addition on the rheological, mechanical, thermal, and electrical properties of the resulting nanocomposite DIW ink.