Stereolithography 3D Printing of Functional Hydrogel Nanocomposites

Hydrogels are recognized as one of the most promising functional materials, as they are dynamic, tunable, biocompatible, biodegradable, and capable of encapsulating large water content. On this basis, hydrogels and their composites are gaining tremendous popularity in various fields such as biomedical, food packaging and agriculture, water purification, sensing, and soft robotics, etc. However, hydrogels utilization is limited by the traditional processing methods, mainly molding for 3D geometries, which is a huge drawback for rapid product development. Moreover, molding techniques suffer from materials limitation as it allows only for a single material utilization. The limitation of conventional fabrication can be overcome by the recent advances in additive manufacturing, which enable the fabrication of complex three-dimensional and hybrid structures with enhanced functionality. Herein, we utilize stereolithography 3D printing to fabricate hydrogel nanocomposite through a novel approach. The direct 3D printing of composite inks, particles in ink, show limitations such as inhomogeneous particle distribution, agglomeration, and scattering of curing light, thus compromising the printed object quality and resolution. To avoid this, a new strategy is devised to introduce nanoparticles into the 3D printed hydrogels post the printing process. Metal salts as precursors of nanoparticles are added into the printing ink to develop different types of nanoparticles, including Fe₃O₄, NiO, and CuO, post the printing. The proposed method allows for the development of hybrid 3D structures in one device without compromising the printing resolution. The versatility of the proposed approach to fabricate 3D hydrogel composites using wide range of nanoparticles offers huge potential to practically utilize hydrogels for water, food and energy nexus.