Bouffier Laurent, Reculusa Stéphane, Ravaine Valérie, Kuhn Alexander
Univ. Bordeaux, ISM, UMR 5255, F-33400, Talence, France.
CNRS, ISM, UMR 5255, F-33400, Talence, France.
Chemphyschem. 2017 Oct 6;18(19):2637-2642. doi: 10.1002/cphc.201700398. Epub 2017 Jun 13.
A new simple and versatile method for the preparation of surface-wetting gradients is proposed. It is based on the combination of electrode surface structuration introduced by a sacrificial template approach and the formation of a tunable molecular gradient by bipolar electrochemistry. The gradient involves the formation of a self-assembled monolayer on a gold surface by selecting an appropriate thiol molecule and subsequent reductive desorption by means of bipolar electrochemistry. Under these conditions, completion of the reductive desorption process evolves along the bipolar surface with a maximum strength localized at the cathodic edge and a decreasing driving force towards the middle of the surface. The remaining quantity of surface-immobilized thiol, therefore, varies as a function of the axial position, resulting in the formation of a molecular gradient. The surface of the bipolar electrode is characterized at each step of the modification by recording heterogeneous electron transfer. Also, the evolution of static contact angles measured with a water droplet deposited on the surface directly reveals the presence of the wetting gradient, which can be modulated by changing the properties of the thiol. This is exemplified with a long, hydrophobic alkane-thiol and a short, hydrophilic mercaptan.
提出了一种制备表面润湿性梯度的新型简单通用方法。该方法基于牺牲模板法引入的电极表面结构化与双极电化学形成的可调分子梯度相结合。该梯度包括通过选择合适的硫醇分子在金表面形成自组装单分子层，以及随后通过双极电化学进行还原解吸。在这些条件下，还原解吸过程在双极表面上进行，最大强度位于阴极边缘，向表面中部的驱动力逐渐减小。因此，表面固定硫醇的剩余量随轴向位置而变化，从而形成分子梯度。通过记录异质电子转移，在修饰的每个步骤中对双极电极的表面进行表征。此外，直接测量沉积在表面的水滴的静态接触角的变化，直接揭示了润湿性梯度的存在，通过改变硫醇的性质可以对其进行调节。这通过长链疏水烷硫醇和短链亲水硫醇得到了例证。
