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Good jetting performance and pigment-dispersing stability are necessary for pigment-based ink-jet inks. This study investigates how the chemical structures of the polymeric dispersants affect the pigment-dispersing stability and jetting performance of ink-jet inks. A series of polymeric dispersants containing styrene (hydrophobic unit) and acrylic acid (hydrophilic unit) with different ratios have been synthesized and used to disperse different pigments. Because 3000–12,000 ink drops can be expelled from the nozzle of a thermal bubble-type ink-jet printer within 1 s, the jetting behavior is related to the rheology variation of a dilute solution under a high shear. An in situ drop formation system has been used to study the high-shear-rate rheology (dynamic surface tension and dynamic viscosity) of a solution with a viscosity lower than 3 cps, which no commercial rheometer can measure. Excellent ink-jet inks can only be produced by the combination of pigments, dispersants, and surfactants with appropriate hydrophilicity. Moreover, the correlation of the pigment surface properties, the chemical structures of the polymeric dispersants, and ink formulation is discussed. The effects of the surfactants and firing conditions on the jetting behavior of the ink-jet ink are also examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1909–1920, 2003

The desorption of C 12 E 8 out of an overcrowded interface due to the sudden shrinkage of a pendant bubble in a quiescent surfactant solution is studied. A video-enhanced pendant bubble tensiometry is utilized for the measurement of the relaxation in surface tension due to the desorption of surfactant. The desorption process is found to be diffusive-kinetic mixed controlled. Rate constants of adsorption/desorption are computed by comparing these tension profiles with numerical solutions, which consider both bulk diffusion and kinetic desorption processes. The values of the kinetic rate constants of C 12 E 8 obtained from the desorption experiment are nearly the same as that obtained from the clean adsorption study (Lin, S. Y., et al., Langmuir 1996, 12, 6530). The concept that there exists a shift in controlling mechanism from diffusion control at dilute concentration to mixed diffusion-kinetic control at more elevated bulk concentration for C 12 E 8 is therefore confirmed.

The adsorption of C12E4 onto a fresh air−water interface was investigated by using video-enhanced pendant bubble tensiometry. From the comparison between the equilibrium surface tension data and the theoretical relaxation profiles predicted by the Frumkin adsorption isotherm, the adsorption process was found to be anticooperative. Dynamic surface tension data for C12E4 molecules absorbing onto a freshly created air−water interface for different bulk concentrations were used for the determination of the controlling mechanism and the evaluation of diffusivity. Comparison was made for the entire relaxation period of the surface tension data and the model predictions. It is concluded that the adsorption process is of diffusion control and the diffusion coefficient is 6.4 × 10-6 cm2/s. The lower limit of the adsorption rate constant of C12E4 were obtained from the theoretical simulation. Besides, the pendant bubble, at which the interface had reached the equilibrium state, was expanded rapidly and a relationsh...