School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, IN 47907-2100, USA.
J Colloid Interface Sci. 2011 Oct 1;362(1):33-41. doi: 10.1016/j.jcis.2011.04.050. Epub 2011 Apr 24.
The effect of Triton X-100 on the colloidal dispersion stability of CuPc-U (unsulfonated and hydrophobic) and CuPc-S (surface sulfonated and hydrophilic) particles in aqueous solutions (water and NaNO(3)) was investigated at 25 °C. Its adsorption density was determined from surfactant concentrations analyzed by an HPLC method with a UV detector. The experimental dispersion stability ratios of the particles were determined from dynamic light scattering (DLS) data, with the Rayleigh-Debye-Gans (RDG) light scattering theory. The adsorption densities of Triton X-100 on both the CuPc-U and CuPc-S increase with increasing concentration of surfactant up to the critical micelle concentration (cmc), and then reach a plateau. The maximum adsorption density Γ(m) is higher for the CuPc-U (d(h)=160 nm) than that for the CuPc-S (d(h)=90 nm). The hydrophobic chains are inferred to be adsorbed onto the surfaces, and the hydrophilic ethylene oxide chains are in a coil conformation. The W(app)-values for the CuPc-U dispersions are affected mainly by the surfactant fractional surface coverage θ. Adding NaNO(3) has no significant effect on the dispersion stability. The stabilization mechanism for the CuPc-U is inferred to be primarily steric, as expected. The stability ratios for the CuPc-S in solutions with NaNO(3) are higher than those for CuPc-U, and decrease with increasing concentration of NaNO(3), indicating that the stabilization is affected by the screening of electrostatic repulsive forces. The zeta potential is not a good predictor of the electrostatic stabilization, pointing to the need for new and improved theories.
在 25°C 下，研究了 Triton X-100 对水中（水和 NaNO₃）CuPc-U（未磺化和疏水性）和 CuPc-S（表面磺化和亲水性）颗粒胶体分散稳定性的影响。通过 HPLC 方法和紫外检测器分析表面活性剂浓度来确定其吸附密度。实验中通过动态光散射（DLS）数据确定了颗粒的分散稳定性比，采用瑞利-德拜-甘斯（RDG）光散射理论。Triton X-100 在 CuPc-U 和 CuPc-S 上的吸附密度随表面活性剂浓度的增加而增加，直至达到临界胶束浓度（cmc），然后达到一个平台。CuPc-U（d(h)=160nm）的最大吸附密度Γ(m)高于 CuPc-S（d(h)=90nm）。推断疏水性链吸附在表面上，而亲水性的氧化乙烯链呈卷曲构象。CuPc-U 分散体的 W(app)-值主要受表面活性剂分数覆盖率θ的影响。添加 NaNO₃ 对分散稳定性没有显著影响。推断 CuPc-U 的稳定机制主要是空间位阻，这是预期的。在含有 NaNO₃ 的溶液中，CuPc-S 的稳定性比 CuPc-U 高，并且随着 NaNO₃浓度的增加而降低，表明稳定作用受到静电排斥力屏蔽的影响。Zeta 电位不是静电稳定的良好预测指标，这表明需要新的和改进的理论。
