3D DLP Fabrication of Electrically Conductive Polypyrrole Nanocomposites

Conjugated polymers such as polypyrrole (PPy) combine high electronic conductivity with good biocompatibility, making them attractive for flexible electronics or biomedical applications. However, their limited processability remains a major challenge, motivating the exploration of advanced fabrication strategies such as additive manufacturing. Among these, light-based 3D printing offers high resolution and geometric freedom. However, its compatibility with strong absorbing and poor soluble materials such as PPy remains limited. Here, we report a new strategy integrating presynthesized, defined PPy nanoparticles into photocurable inks for digital light processing (DLP) 3D printing. Four distinct PPy nanoparticles have been synthesized via chemical oxidation polymerization using FeCl₃ or APS as oxidants and SDS or DBSA as surfactants in aqueous media. The resulting materials have been characterized in depth in terms of their structural, optical, morphological, and electrical properties. Stable inks containing 3.0-5.0 wt% PPy nanoparticles enable DLP printing at 405 nm, yielding single- and multilayer 3D structures with high fidelity, rapid curing and electrical conductivities up to 3 × 10^-2 S cm^-1. This work establishes a new route for direct incorporation of PPy into inks for DLP printing, opening new opportunities for the additive manufacturing of electrically conductive polymer materials.