Alkylphosphonate modified aluminum oxide surfaces
Alkylphosphonate modified aluminum oxide surfaces
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DOI：
10.1021/jp061327a
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发表时间：
2006-06-08
影响因子：
3.3
通讯作者：
Bhushan, B.
中科院分区：
文献类型：
--
作者：
Hoque, E.;DeRose, J. A.;Bhushan, B.
铝的表面性质，例如化学成分、粗糙度、摩擦、粘附和磨损，可以在微/纳米机电系统的性能中发挥重要作用，例如，数字化电子设备。采用X射线光电子能谱（XPS）、接触角测量和原子力显微镜（AFM）研究了十八烷基膦酸（ODP/Al）、癸基膦酸（DP/Al）和辛基膦酸（OP/Al）在铝基体上的化学反应。XPS分析证实了烷基膦酸酯分子在ODP/Al、DP/Al和OP/Al上的存在。纯水在ODP/Al和DP/Al上的座滴静态接触角通常大于115度，在OP/Al上通常小于105度，表明所有膦酸反应的Al样品都是高度疏水的。ODP/Al、DP/Al、OP/Al和裸Al的均方根表面粗糙度小于15 nm，如通过AFM测定的。ODP/Al和DP/Al的表面能分别为21和22 mJ/m（2），而OP/Al的表面能为25 mJ/m（2）。为了更好地了解它们的微/纳米摩擦学性能，我们采用摩擦力显微镜对ODP/Al和OP/Al进行了研究。ODP/Al的摩擦系数最低，而裸Al的摩擦系数最高。ODP/Al和OP/Al的粘附力相当。
The surface properties of aluminum, such as chemical composition, roughness, friction, adhesion, and wear, can play an important role in the performance of micro-/nano-electromechanical systems, e.g., digital micromirror devices. Aluminum substrates chemically reacted with octadecylphosphonic acid (ODP/Al), decylphosphonic acid (DP/Al), and octylphosphonic acid (OP/Al) have been investigated and characterized by X-ray photoelectron spectroscopy (XPS), contact angle measurements, and atomic force microscopy (AFM). XPS analysis confirmed the presence of alkylphosphonate molecules on ODP/Al, DP/Al, and OP/Al. No phosphonates were found on bare Al as a control. The sessile drop static contact angle of pure water on ODP/Al and DP/Al was typically more than 115 degrees and on OP/Al typically less than 105 degrees indicating that all phosphonic acid reacted Al samples were highly hydrophobic. The root-mean-square surface roughness for ODP/Al, DP/Al, OP/Al, and bare Al was less than 15 nm as determined by AFM. The surface energy for ODP/Al and DP/Al was determined to be approximately 21 and 22 mJ/m(2), respectively, by the Zisman plot method, compared to 25 mJ/m(2) for OP/Al. ODP/Al and OP/Al were studied by friction force microscopy, a derivative of AFM, to better understand their micro-/nano-tribological properties. ODP/Al gave the lowest coefficient of friction values while bare Al gave the highest. The adhesion forces for ODP/Al and OP/Al were comparable.