Weston J S, Venkataramani D, Aichele C P, Grady B P, Harwell J, Resasco D
School of Chemical, Biological and Materials Engineering, University of Oklahoma , Norman, Oklahoma 73019, United States.
Langmuir. 2014 Dec 16;30(49):14982-90. doi: 10.1021/la503442a. Epub 2014 Dec 1.
Hydroxyl groups on the surface of metal oxide nanoparticles (nps) can be protonated or deprotonated depending on solution pH, changing both the magnitude and sign of the nps' surface charge. Binary mixtures of fumed metal oxide nps, dispersed in water at a solution pH where one species is positively charged and the other is negatively charged, form pseudosolid gels at volume fractions as low as 1.5 vol %. This work maps out regions of gel formation for binary mixtures of silica and alumina nps, silica and titania nps, and alumina and titania nps. The microscopic structure of these gels is investigated using transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), acoustic spectroscopy, and light microscopy.
金属氧化物纳米颗粒（NPs）表面的羟基可根据溶液pH值发生质子化或去质子化，从而改变NPs表面电荷的大小和符号。气相法金属氧化物NPs的二元混合物，在一种物质带正电而另一种物质带负电的溶液pH值下分散于水中，在低至1.5体积%的体积分数下形成假固体凝胶。这项工作绘制了二氧化硅和氧化铝NPs、二氧化硅和二氧化钛NPs以及氧化铝和二氧化钛NPs二元混合物的凝胶形成区域。使用透射电子显微镜（TEM）、小角X射线散射（SAXS）、声学光谱和光学显微镜研究了这些凝胶的微观结构。
