Additive manufacturable polyimide vitrimer sensors for soft structural materials

Abstract

This study introduces a novel polyimide vitrimer ink specifically formulated for additive manufacturing on non-planar textile surface (i.e., Kevlar) substrates, aiming to advance the integration of strain sensors in aerospace and defense applications. The ink incorporates disulfide exchanges that enable reversible covalent adaptability, facilitating post-processing modifications and enhancing material recyclability. The synthesis involved a two-step process under nitrogen atmosphere, starting with the formation of polyamic acid (PAA) from 4-amino phenyl disulfide and pyromellitic dianhydride, followed by making the polymer UV-sensitive through the addition of a DMAEMA salt solution and a photoinitiator. Optimal printing parameters were established through experimental tuning of viscosity and modulus, enabling effective direct ink writing (DIW) on Kevlar. The printed sensors exhibited high sensitivity and durability under mechanical stress. Notably, the vitrimer’s disulfide linkages allowed for straightforward removal from substrates using a tailored solvent mixture, underscoring the potential for reusability and recycling in practical applications. This research demonstrates that polyimide vitrimers can be effectively used to create high-performance, adaptable, and recyclable sensors via additive manufacturing, providing a significant advancement in the field of smart materials for dynamic and harsh environments.