Effect of ammonium polyacrylate on dispersion and rheology of aqueous ITO nanoparticle colloids
Effect of ammonium polyacrylate on dispersion and rheology of aqueous ITO nanoparticle colloids
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聚丙烯酸铵对水性ITO纳米颗粒胶体分散和流变的影响
DOI：
10.1016/j.colsurfa.2005.09.046
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
F. Tzeng
中科院分区：
文献类型：
--
作者：
W. Tseng;F. Tzeng
通过流变学表征检查氧化铟锡 (ITO) 纳米颗粒在水中的分散情况。当将 0.5-2wt.% 的聚丙烯酸铵 (NH4PA) 引入水性纳米颗粒胶体时，在 100s−1 的剪切速率下，粘度显着降低超过 99%。 Zeta电位测量表明NH4PA分子优先吸附在纳米粒子表面，在粒子表面之间提供足够的电空间斥力，从而降低流动阻力。悬浮液流变学类似于剪切速率 (γ˙) 范围为 10 至 ∼500s−1 的牛顿流动。随着 γ˙ 进一步增加，胶体流变特性转变为剪切增稠流。纳米颗粒悬浮液从液体形式转变为“固体”块体时的最大固体浓度（Φmax）被确定为在γ˙=100s−1时Φmax=0.34。这种较低的 phimax 值表明，尽管存在 NH4PA 表面活性剂分子，但当颗粒间分离减少到临界水平时，纳米颗粒悬浮液中涉及的范德华引力最终会压倒所有其他颗粒间力和流体动力。
Dispersion of indium tin oxide (ITO) nanoparticles in water is examined via rheological characterizations. A pronounced viscosity reduction exceeding 99% at a shear-rate of 100s−1resulted when an ammonium polyacrylate (NH4PA) of 0.5–2wt.% was introduced into the aqueous nanoparticle colloids. Zeta-potential measurement reveals that the NH4PA molecules adsorb preferentially on the nanoparticle surface, providing a sufficient electrosteric repulsion between particle surfaces so that the flow resistance was reduced. Suspension rheology resembles that of the Newtonian flow over a shear-rate (γ˙) range 10 to ∼500s−1. The colloidal rheology then changes into a shear-thickening flow as γ˙ was further increased. A maximum solids concentration (ϕmax) at which the nanoparticle suspensions changes from a liquid-like form into a “solid” bulk is determined as ϕmax=0.34 at γ˙=100s−1. This low value of ϕmaxsuggests that the van der Waals attraction involved in the nanoparticle suspensions eventually prevails over all other interparticle and hydrodynamic forces when the interparticle separation is reduced to a critical level, despite the presence of the NH4PA surfactant molecules.