Wąsik Patryk, Slastanova Anna, Wąsik Jacek M, Snow Tim, de Bruin Alexander Gerrit, Arnold Thomas, Briscoe Wuge H
National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States.
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K.
Langmuir. 2025 Jul 22;41(28):18730-18740. doi: 10.1021/acs.langmuir.5c01989. Epub 2025 Jul 9.
Mechanisms for surface pattern formation from evaporation of a nanofluid sessile drop are not well understood. In contrast to the coffee-ring effect from inert particles, rapid chemical and morphological transformation of reactive nanoparticles upon rapid evaporative drying are challenging to probe experimentally. Here, using grazing-incidence X-ray surface scattering, the nanostructure of nascent surface patterns has been probed as a ZnO nanofluid sessile drop rapidly dries. The high temporal resolution enabled by the high flux of synchrotron X-rays allows the observation of the emergence of Zn(OH) surface crystals from the onset of evaporation and their rapid evolution into the final residual surface pattern, transient layered complexes evident from the temporary appearance of X-ray diffraction peaks preceding Zn(OH) formation. The results offer mechanistic insights of morphogenesis of surface patterns from evaporation-induced self-assembly and self-organization of reactive nanofluids, previously untenable using other experimental methods.
纳米流体固着液滴蒸发形成表面图案的机制尚未得到充分理解。与惰性颗粒的咖啡环效应不同，反应性纳米颗粒在快速蒸发干燥时的快速化学和形态转变在实验上难以探究。在此，利用掠入射X射线表面散射技术，在ZnO纳米流体固着液滴快速干燥时对新生表面图案的纳米结构进行了探测。同步加速器X射线的高通量所带来的高时间分辨率使得能够观察到从蒸发开始时Zn(OH)表面晶体的出现以及它们迅速演变成最终的残余表面图案，在Zn(OH)形成之前X射线衍射峰的短暂出现表明存在瞬态层状络合物。这些结果为蒸发诱导反应性纳米流体的自组装和自组织形成表面图案的形态发生提供了机理见解，而这在以前使用其他实验方法是无法实现的。
