Fabrication of Surface Charge Gradients in Open-Tubular Capillaries and Their Characterization by Spatially Resolved Pulsed Streaming Potential Measurements

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• 作者：Balamurali Kannan ; Kenji Nokura ; Julio C. Alvarez ; Daniel A. Higgins ; Maryanne M. Collinson
• 刊名：Langmuir
• 出版年：2013
• 出版时间：December 10, 2013
• 年：2013
• 卷：29
• 期：49
• 页码：15260-15265
• 全文大小：266K
• 年卷期：v.29,no.49(December 10, 2013)
• ISSN：1520-5827

文摘

Surface charge gradients have been formed on the inside surface of 75 渭m i.d. silica capillaries via controlled rate infusion using 3-aminopropyltriethoxysilane as the reactive precursor. These 400 mm length gradients have been characterized using spatially resolved streaming potential measurements, from which the zeta potential as a function of distance was determined. The gradient capillaries exhibited a gradual variation in zeta potential from top to bottom, whereas uniformly modified and as-received capillaries were relatively homogeneous along their length. For a gradient prepared with a relatively high concentration of aminosilane, the zeta potential changed over 60 mV from one end of the capillary to the other, yielding a variation in the magnitude of the apparent surface charge of 7 fold. By changing the concentration of the aminoalkoxysilane and/or the rate of infusion, both the value of the zeta potential (and hence surface charge) and its spatial profile (i.e., rate of change with distance) could be manipulated.