Study On Three-Dimensional Printing Based On TiO₂ Powder

Three-dimensional printing have become one of the most attractive hotspots around the world because of advanced principle of additive manufacturing and potential revolutionary application in many fields.The integration of metal oxides into three-dimensional(3D)printing technique enables the manufacturing of multi-functional 3D porous structures with controllable macro/microstructures,which making them have great potential and opportunities in many applications.Particularly,porous scaffolds based on metal oxides with advantages of low-density and high relative mechanical strength,tunable thermal properties,abundant micro or/and nano-sized pores,have been intensively investigated due to their many emerging applications,such as filtration,thermal insulation,biomedical scaffolds,catalyst supports and energy storage.Recently,3D printing has been applied to fabricate a variety of metal oxide scaffolds,such as aluminum oxide(Al2O3),calcium silicate(CaSiO3),barium titanate(BaTiO3)and titanium dioxide(TiO2).So far,3D printing of TiO2 dense scaffolds or components by direct writing of mainly sol-gel inks have been demonstrated.However,the tedious prepared process resulted in low throughput of the printable sol-gel inks from the expensive metal alkoxides precursors,which hinders their practical and commercial applications.3D printing of porous TiO2 scaffolds with relatively high structural strength,and applicable to low-cost and large-scale production still remains a formidable challenge.In this study,we report 3D printing of porous titanium dioxide(TiO2)scaffolds with tunable microstructure,geometry and structural strength via a simple direct-ink-writing(DIW)assembly route based on the particle-based TiO2 inks.This new type of TiO2 inks with controlled rheological properties can be directly printed in air at room temperature without the need for additional in-situ or post-solidification treatments,which providing controllability and flexibility over the printing process.Importantly,with the help of flexible DIW approach,the geometry and pores in mm-scale were controlled by adjusting the printing parameters,while the pores in micro-and nanoscale were tuned by incorporating TiO2 nanoparticles into the inks.The porous microstructure combined with heptadecafluorodecyltrimethoxysilane(HTMS)surface modification endow the TiO2 scaffolds possess good hydrophobic behavior.We also demonstrate 3D printed scaffold with color switching property,discovering the applications of 3D printed samples in photochromic field.Additionally,other material can be easily incorporated into the porous 3D TiO2 scaffolds by simply mixing the powders into the particle-based inks,which exhibits endless possibility of producing multi-functional components to meet the required functions for different applications.We also demonstrate 3D printed scaffold with color switching property,discovering the applications of 3D printed samples in photochromic field.