Spatial Control of Condensation and Freezing on Superhydrophobic Surfaces with Hydrophilic Patches
Spatial Control of Condensation and Freezing on Superhydrophobic Surfaces with Hydrophilic Patches
复制标题
DOI：
10.1002/adfm.201300418
复制
发表时间：
2013-09-25
影响因子：
19
通讯作者：
Hatton, Benjamin D.
中科院分区：
文献类型：
--
作者：
Mishchenko, Lidiya;Khan, Mughees;Hatton, Benjamin D.
某些自然生物体使用微图案表面化学或冰成核物质来控制水凝结和冰成核，以在极端条件下生存。作为与这些生物方法的类比，研究表明，沉积在超疏水柱尖端上的功能化亲水聚合物和颗粒可诱导对微米级水凝结和冻结的精确地形控制。自下而上的沉积工艺用于利用非润湿水溶液在超疏水表面上的有限接触面积。这些几何结构尖端上的亲水聚合物沉积可以对微米级水滴的成核、生长和聚结进行空间控制。亲水尖端使水滴成核，具有极其均匀的成核和生长速率、均匀的尺寸、增强的抗聚结稳定性以及不对称的液滴形态。通过在这些结构尖端沉积冰核 AgI 纳米颗粒也证明了对冻结行为的控制。尖端上的亲水聚合物和 AgI 颗粒的这种组合用于实现微米级冰成核的模板化。初步结果表明，用这种方法可以控制冰晶的大小、空间对称性和位置。这种方法可以作为系统分析微米级凝结和冻结现象的平台，并作为自然系统的模型。
Certain natural organisms use micro-patterned surface chemistry, or ice-nucleating species, to control water condensation and ice nucleation for survival under extreme conditions. As an analogy to these biological approaches, it is shown that functionalized, hydrophilic polymers and particles deposited on the tips of superhydrophobic posts induce precise topographical control over water condensation and freezing at the micrometer scale. A bottom-up deposition process is used to take advantage of the limited contact area of a non-wetting aqueous solution on a superhydrophobic surface. Hydrophilic polymer deposition on the tips of these geometrical structures allows spatial control over the nucleation, growth, and coalescence of micrometer-scale water droplets. The hydrophilic tips nucleate water droplets with extremely uniform nucleation and growth rates, uniform sizes, an increased stability against coalescence, and asymmetric droplet morphologies. Control of freezing behavior is also demonstrated via deposition of ice-nucleating AgI nanoparticles on the tips of these structures. This combination of the hydrophilic polymer and AgI particles on the tips was used to achieve templating of ice nucleation at the micrometer scale. Preliminary results indicate that control over ice crystal size, spatial symmetry, and position might be possible with this method. This type of approach can serve as a platform for systematically analyzing micrometer-scale condensation and freezing phenomena, and as a model for natural systems.