The modified surfaces were characterized for spectral absorbance bonding information, weight yield of TMAPS modification, surface composition, surface charge as a function of pH, and surface area with an average meso- and micropore size.
TMAPS-modified boehmites were characterized with FTIR to confirm chemical bonding, with TGA to quantify the weight of bonded TMAPS, and with XPS to analyze the elemental composition of the modified boehmite surface.
Bands that increased in intensity with stoichiometric ratio and corresponding to the surface TMAPS group were observed at 1491 (asym str) and 1479 (sym str), H-C(-N); 1241 (bend), Si-C; and 1000 [cm.sup.-1] (N-C), which showed the presence of TMAPS in the modified samples.
Onset for weight loss of TMAPS from the boehmite surface was relatively low, near 235[degrees]C, compared to that of boehmite, whose weight loss has an onset at 540[degrees]C.
Theoretical weight loss for added TMAPS was calculated as 2.3% based on 58 [[Angstrom].sup.2]/surface TMAPS site, molecular weight of the volatile portion of TMAPS (136.5g/mol TMAPS), the measured weight loss per gram of native boehmite (0.156 g/g), and the nonvolatile silica weight added to one gram of boehmite (0.052 g/mol TMAPS).
Aluminum content after modification was about 25%; thus, it appeared the X-ray beam was able to penetrate the TMAPS surface to visualize the underlying aluminum oxide, which further supported the presence of a thin surface layer of TMAPS much less than 50 [Angstrom] in thickness.
The reason for the decrease in zeta potential near pH 12 was unclear, but could have resulted from deprotonation of residual TMAPS silanols or underlying boehmite surface groups at extreme pH.
BET PORE AND SURFACE AREA ANALYSIS: Specific surface area, pore size, and pore volume for meso-and micropores were characterized and correlated with the content of bonded TMAPS on the boehmite surface.
The viscosity of TMAPS-modified boehmite showed a decreasing trend with an increasing amount of TMAPS to 6%, with similar viscosity shown for 8%.
The number of dye molecules per theoretical surface charge for each sample was calculated from moles of TMAPS per square area, as shown in Table 4 and plotted in Figure 7.
However, modified boehmites showed proportionately deeper colors as a function of increasing TMAPS modification.
Delta E values larger than 5 for green and yellow colors suggested that the yellow dye used in the commercial CMYK ink cartridge was water sensitive, bulky in structure, or not well mordanted by TMAPS. Similarly, lower adsorption capacity for the DY50 dye was observed, perhaps in part because of the large ionic demand of the yellow dye, containing four sulfonate groups.