Abstract
Zeta potential of ink with three different cationic surfactants: dodecyl-, tetradecyl-, and hexadecyl or cetyl-trimethylammonium bromides (i.e., DTAB, TTAB, and CTAB, respectively) was measured at two pH levels of 11 and 12. These surfactants are chemically different in the number of carbon atoms of the alkyl tail group (i.e., 12, 14, and 16 for DTAB, TTAB, and CTAB, respectively). The zeta potential of ink particles increases and fractional ink removal increases with increasing alkyl chain size and increases with surfactant concentration, plateauing at some higher concentration. The zeta potential of each surfactant at pH 12 was higher than that at pH 11, while the efficiency for ink removal of these surfactants worked particularly well at pH 12. Inducing a higher negative charge on the ink particles by increasing pH or surfactant hydrophobicity and concentration is correlated with ink removal as repulsion between ink particles and polymer surface increases and dispersion stability of detached ink particles increases, presumably due to increased surfactant adsorption on the ink particles.
