Tris (tris(hydroxymethyl)aminomethane) was used as the dispersant to enhance
the colloidal stability of titania nanoparticles in different alcohols
(methanol, ethanol, isopropanol and butanol). Acetic acid (AA) was also used
to increase the ionization of Tris via acid-base reaction. The effect of Tris
on the stability of suspensions in the absence as well as the presence of AA
was investigated by different analysis, such as conductivity and zeta
potential measurement as well as FTIR analysis. It was found that Tris is
protonated and adsorbed on the titania nanoparticles. It enhances their zeta
potential and thus colloidal stability. The optimum concentration of Tris
increased with molecular weight of alcohol (0.1, 0.2, 0.3 and 0.6 g/l for
methanolic, ethanolic, isopropanolic and butanolic suspensions,
respectively). The optimum concentration of Tris decreased to 0.1 g/ l for
all AA containing suspensions except the methanolic ones. Titania coating was
obtained by electrophoretic deposition (EPD) performed at 60 V. The current
density and in-situ kinetics of deposition were recorded during EPD. It was
found that the kinetics of EPD is the fastest for the suspensions with the
optimum concentration of Tris (the highest zeta potential). Calcium phosphate
phases were formed on the surface of titania coating after its immersion for
one week in SBF at 37.5?C.