Coalescence and movement of nanobubbles studied with tapping mode AFM and tip-bubble interaction analysis
Coalescence and movement of nanobubbles studied with tapping mode AFM and tip-bubble interaction analysis
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DOI：
10.1088/0953-8984/20/48/485004
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发表时间：
2008-12-03
影响因子：
2.7
通讯作者：
Maali, Abdelhamid
中科院分区：
文献类型：
--
作者：
Bhushan, Bharat;Wang, Yuliang;Maali, Abdelhamid
利用原子力显微镜（AFM）在攻丝模式（TMAFM）下对聚苯乙烯（PS）包覆硅片进行了浸入去离子水的成像。如前所述，在PS表面观察到球形帽状结构域，称为纳米气泡。实验表明，除了众所周知的扫描载荷参数外，扫描速度也是影响纳米气泡聚并的重要参数。研究了纳米气泡的聚结过程。研究发现，在聚并过程中，小的纳米气泡很容易移动并合并成较大的纳米气泡。基于AFM悬臂端与气泡在TMAFM力调制模式下的相互作用，提取了给定气泡的高度和附着力信息。采用粘弹性模型计算了纳米气泡的相互作用刚度和阻尼系数，为研究纳米气泡的力学性能提供了一种方法。利用该模型进一步研究了表面张力对吸力的影响以及接触角滞后对尖泡相互作用过程中相互作用阻尼系数变化的影响。
Imaging of a polystyrene (PS) coated silicon wafer immersed in deionized (DI) water was conducted using atomic force microscopy (AFM) in the tapping mode (TMAFM). As reported earlier, spherical cap-like domains, referred to as nanobubbles, were observed to be distributed on the PS surface. Experiments reveal that, in addition to the well-known parameter of scan load, scan speed is also an important parameter which affects nanobubble coalescence. The process of nanobubble coalescence was studied. It was found that during coalescence, small nanobubbles were easily moved and merged into bigger ones. Based on the interaction between the AFM cantilever tip and a bubble in the so-called force modulation mode of TMAFM, bubble height and adhesive force information for a given bubble was extracted. A viscoelastic model is used to obtain the interaction stiffness and damping coefficient, which provides a method to obtain the mechanical properties of nanobubbles. The model was further used to study the effect of surface tension force on attractive interaction force and contact angle hysteresis on the changes of the interaction damping coefficient during tip-bubble interaction.