4D Printing Nanocomposite Hydrogel Based on PNIPAM and Prussian Blue Nanoparticles Using Stereolithography

The potential of photoactive Prussian blue nanoparticles dispersed in thermo-responsive PNIPAM hydrogels in 4D printing using a stereolithography is investigated with digital light processing. The proportion of Prussian blue nanoparticles used in the resin is chosen to deliver a significant photothermal effect providing a heating above the volume phase transition temperature of the final nanocomposite hydrogels; while, giving only a limited effect on light scattering during the 3D printing process. Four formulations with various amounts of Prussian blue nanoparticles are used to print 3D structures with different shapes, such as Aztec pyramids, cylinders, gyroid porous cubes, and porous films. The shrinkage effect triggered by light irradiation at 808 nm on the as-obtained nanocomposite hydrogels is demonstrated through the delivery of a representative molecule fluorescein and a triggered 4D shape-morphing effect. Nanocomposite hydrogels associating photoactive Prussian blue (PB) nanoparticles with a thermo-responsive matrix, poly(N-isopropylacrylamide are elaborated via a digital litography processing . The hydrogel-based objects are subjected, on request under Near InfraRed irradiation, to a 4D shape transformation in the solid state or to the release of fluorescein in solution.image