Investigation of icephobic behavior of surfaces with tunable properties

[66426] Constantine megaridis水滴在固体表面上的撞击和冻结不仅是一个重要的基本问题，也是一个实际问题，对暴露在环境中的设备和机械的不间断运行提出了严峻的挑战。在过去的几年里，阻碍冰形成的表面（又称疏冰表面）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。尽管在这方面的工作有限，但液滴对表面的影响是环境中冰形成的常见机制，缺乏彻底的基本理解。对喷墨延迟冻结产生的过冷水微滴一个接一个地积聚在各种表面（包括超疏水涂层）的初步研究表明，在这个问题中，表面粗糙度的影响可能与表面能（即润湿性）同样重要。这项工作将研究过冷水滴在受控微纳米级纹理、规定润湿性（从疏水到超疏水）和自清洁能力的表面上的影响和冻结。冻结延迟将通过高空间和时间分辨率仪器进行量化；测量的冻结延迟将用于评估每个表面的疏冰潜力。分析润湿性（接触角）、自清洁能力（液滴滚脱倾斜角）、液滴冲击参数（直径、速度、入射角）和液滴/表面温差对液滴弹跳、冻结和冰/霜积累的影响。除了上述延迟冰形成的被动方法外，局部热输入将作为一种主动方法进行研究，通过使用超疏水、导电、纳米颗粒填充、聚合物基复合涂层来减少冰的形成/积聚。s实验室。这些新型涂层具有可控的微/纳米结构、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。知识价值：这项工作被认为具有高度的变革性。它解决了一个尚未彻底调查的基本问题，尽管它与实际应用中的恐冰性高度相关。这项研究利用了最近发展起来的具有良好控制的微/纳米结构、可调节的润湿性、自清洁能力和电性能的超驱避聚合物复合涂层，这些都是研究所必需的工具。该问题涉及流体物理和热输运的丰富现象、非平衡相变和超驱避多功能材料。更广泛的影响：拟议的项目将丰富疏冰表面设计的科学基础，如果成功，有可能指导具有优越性能的疏冰表面的开发。这项研究将促进发现和基本理解，同时通过平行教育/外展组成部分促进教学、培训和学习。PI将与当地一所少数民族高中合作，通过让这些学生和他们的老师参与大学实验室的前沿研究，让他们接触到令人兴奋的纳米科学世界。参与研究的研究生和本科生将作为高中学生的导师。

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.