Investigation of icephobic behavior of surfaces with tunable properties

1066426：康斯坦丁·梅加里水滴对固体表面的冲击和冻结不仅是一个非常重要的问题，而且是一个实际问题，对暴露在环境中的设备和机械的不间断运行构成了严峻的挑战。在过去的几年里，延缓结冰的表面(也就是疏水表面)引起了越来越多的关注，超疏水表面被认为是一种可能的解决方案。尽管在这一领域的工作有限，但水滴对表面的影响是环境中形成冰的一种常见机制，缺乏彻底的基础了解。对喷墨产生的过冷水微滴延迟冻结的初步工作表明，在这个问题上，表面粗糙度的影响可能与表面能量(即润湿性)同等重要。这项工作将研究过冷水滴对具有受控微纳尺度织构、指定润湿性(从疏水到超疏水)和自清洁能力的表面的影响和冻结。冻结延迟将通过高空间和时间分辨率仪器来量化；测量的冻结延迟将被用来评估每个表面的冰冷潜力。将分析润湿性(接触角)、自洁能力(液滴滚出倾角)、液滴撞击参数(直径、速度、入射角)和液滴/表面温差对液滴反弹、冻结和结冰/结霜的影响。除了上述延迟结冰的被动方法外，局部热输入将被视为一种减少结冰/结冰的主动方法，方法是使用由皮奥？S实验室开发的超疏水、导电、纳米颗粒填充、聚合物基复合涂层。这些新型涂层具有良好的微/纳米织构、可调的润湿性(接触角)、自清洁能力(接触角滞后)和良好的电性能。智力价值：这项工作被认为具有很强的变革性。它解决了一个尚未彻底调查的基本问题，尽管它与疏冰性具有很高的相关性，因为它与实际应用有关。这项拟议的研究利用了超排斥聚合物复合涂层的最新发展，这些涂层具有良好的微/纳米结构、可调的润湿性、自清洁能力和电性能，这些都是拟议研究的必要工具。该问题涉及丰富的流体物理和热传输现象、非平衡相变和超排斥多功能材料等。广泛影响：提出的程序将丰富疏水表面设计的科学基础，如果成功，将有可能指导具有优异性能的疏水表面的开发。这项研究将促进发现和基本理解，同时通过平行的教育/推广部分促进教学、培训和学习。PI将与当地一所为少数族裔服务的高中合作，让这些学生和他们的老师接触到令人兴奋的纳米科学世界，让他们参与在大学实验室进行的尖端研究。参与研究的研究生和本科生将担任高中生的导师。

1066426:Constantine MegaridisThe impact and freezing of water droplets on solid surfaces is a problem not only of intense fundamental interest but also a practical one, posing severe challenges to the uninterrupted operation of equipment and machinery exposed to the environment. Over the past few years, surfaces that retard ice formation (a.k.a. icephobic surfaces) have attracted increased attention, with superhydrophobic surfaces suggested as a possible solution. Despite some limited work in this area, the impact of droplets on surfaces, which is a common mechanism of ice-formation in the environment, lacks a thorough fundamental understanding. Preliminary work on delayed freezing of inkjet generated supercooled water microdroplets accumulating one-after-the-other on various surfaces -including superhydrophobic coatings- revealed that the effect of surface roughness in this problem might be equally as important as surface energy (i.e. wettability).The work will examine the impact and freezing of supercooled-water droplets on surfaces with controlled micro-to-nanoscale texture, prescribed wettability (ranging from hydrophobic to superhydrophobic) and self-cleaning ability. Freezing delays will be quantified by means of high spatial and temporal resolution instrumentation; the measured freezing delays will be used to evaluate the icephobic potential of each surface. The effects of wettability (contact angle), self-cleaning ability (droplet roll-off tilt angle), droplet impact parameters (diameter, velocity, incidence angle) and droplet/surface temperature difference on droplet bounce, freezing and ice/frost accumulation will be analyzed. In addition to the above passive means of delaying ice formation, localized heat input will be examined as an active method to reduce ice formation/build-up by using superhydrophobic, electrically-conducting, nanoparticle-filled, polymer-based, composite coatings developed in the PI?s laboratory. These novel coatings feature well-controlled micro/nanotexture, tunable wettability (contact angle), self-cleaning ability (contact angle hysteresis), and favorable electrical properties. Intellectual Merit: The work is believed to be highly transformative. It addresses a fundamental problem that has not yet been investigated thoroughly, although it is of high relevance to icephobicity as it pertains to practical applications. The proposed study takes advantage of recent developments on super-repellent polymer composite coatings that feature well-controlled micro/nanotexture, tunable wettability, self-cleaning ability and electrical properties, all necessary tools for the proposed investigation. The problem involves rich phenomena in fluid physics and heat transport, non-equilibrium phase change, and super-repellent multifunctional materials.Broader Impacts: The proposed program will enrich the science base for icephobic surface design, and if successful, has the potential to guide development of icephobic surfaces with superior properties. The research will advance discovery and fundamental understanding, while promoting teaching, training, and learning by means of a parallel education/outreach component. The PI will partner with a local minority-serving high school to expose these students and their teachers to the exciting world of nanoscience by involving them in cutting-edge research pursued in a university laboratory. Graduate and undergraduate students who will be involved in the research will serve as mentors to the high school students.