Self-assembled titanium-based macrostructures with hierarchical (macro-, micro-, and nano) porosities: A fundamental study

This study details the novel self -assembly of sodium titanate converted Ti -based microspheres into hierarchical porous 3D constructs, with macro-, micro-, and nanoporosity, for the first time. Ti6Al4V microspheres were suspended into 5 M NaOH (60 C-degrees /24 h) solutions, with extensive variations in microsphere:solution ratios to modify microsphere interaction and initiate self -assembly through proximity merging of titanate surface dendritic growth. The formed structures, which either produced 1) unbonded, sodium titanate-converted microspheres; 2) flat (non-macroporous) scaffolds; or 3) open, hierarchically porous scaffolds, were then assessed in terms of their formation mechanism, chemical composition, porosity, as well as the effect of post -heat treatments on compressive mechanical properties. It was found that specific microsphere:solution ratios tended to form certain structures (<(1)/(3) powder, 0.5 to 3 porous, >3 flat non-macroporous, >8 powder) due to a combination of microsphere freedom of movement, H-2 gas bubble formation, and exposed surface reactivity. This promising discovery highlights the potential for lower temperature, simplistic production of 3D constructs with modifiable chemical properties due to the ion -exchange potential of titanate structures, with clear applications in a widerange of fields, from medical materials to catalysts.