EAGER: An Innovative Way to Enhance Cross-Plane Thermal Conductivity of Polymer-Based Thin Films

当前电子设备最关键的问题之一是热管理——从纳米级区域去除热量。由于功率密度呈指数增长，器件尺寸显著减小，热强度急剧增加。热管理成为推进各种重要国防、空间和商业应用的关键瓶颈。开发节能冷却技术是提高电子设备节能、性能、可靠性和使用寿命的关键。热界面材料的革新对于散热技术的发展至关重要，因为热界面材料的热阻占设备到空气总热阻的很大一部分。具有高交叉平面导热性的更好的热界面材料可以减小其他组件的尺寸，成本和重量。该项目建议研究具有垂直排列或约束链的聚合物基薄膜，作为热界面材料的潜在创新解决方案。通过提高界面的散热效率，所提出的工作将显著有助于全球可持续能源解决方案。研究成果将通过以下方式传播给更广泛的受众：1)面向大学预科学生的拓展活动；2)本科生的研究活动和非正式会谈；3)与行业合作伙伴的合作。在目前成功的基础上，PI将尽一切努力促进学术多样性，并招收代表性不足的学生。本提案的研究目的是验证垂直排列或限制在垂直排列的纳米通道中的聚合物链可以增强薄膜的平面导热性的假设，并了解增强的最佳条件，如果有的话。目标是加速合理设计具有高跨平面导热系数的聚合物或聚合物-无机杂化薄膜，用于变革性热应用，如有前途的电子热管理热界面材料。将进行分子动力学模拟来计算我们感兴趣的薄膜的热导率，以1)建立垂直排列和其他方向（水平排列和非晶态薄膜）之间的基线比较；2)构建构性关系；3)通过研究振动模式和量化链结晶度和约束来了解微观机制。如果这一假设得到证实，这将为设计具有高平面交叉导热性的聚合物基薄膜提供令人兴奋的机会。提出的研究将促进对垂直取向或约束下聚合物薄膜热传输的基本理解，并回答垂直取向或约束是否可能实现高的跨平面导热性，以及如何优化这种增强（如果有的话）。这种独特形态的聚合物基薄膜的热输运过程的基础研究突出了这项工作的智力价值。

#1641103Tain, ZhitingOne of the most critical problems with current electronic devices is thermal management - removing heat from nanoscale regions. The heat intensities increase steeply, created by an exponential increase in power densities and a significant decrease in device sizes. Thermal management becomes a critical bottleneck for the advancement of a variety of important defense, space and commercial applications. Developing energy-efficient cooling technologies is the key to improving energy saving, performance, reliability and lifetime of electronic devices. Revolutionizing thermal interface materials is crucial for the development of heat rejection technologies because the thermal resistance of thermal interface materials comprises a significant fraction of the total thermal resistance from device to air. Better thermal interface materials with high cross-plane thermal conductivity allow reduction of size, cost and weight of other components. This project proposes to study polymer-based thin films with vertically aligned or confined chains as a potentially innovative solution to thermal interface materials. By improving the efficiency of heat rejection at the interface, the proposed work will notably contribute to global sustainable energy solutions. The research findings will be disseminated to a broader audience through 1) outreach activities for precollege students 2) undergraduate research activities and casual talks and 3) collaboration with industry partners. Building on current success, the PI will make every effort to promote academic diversity and recruit underrepresented students.The research objective of this proposal is to test the hypothesis that polymer chains, which are vertically aligned or confined in vertically aligned nanochannels, can enhance the cross-plane thermal conductivity of thin films and to understand the optimal conditions for enhancement, if any. The goal is to accelerate rational design of polymer or polymer-inorganic hybrid thin films with high cross-plane thermal conductivity for transformative thermal applications such as promising thermal interface materials for electronics thermal management. Molecular dynamics simulations will be performed to compute the thermal conductivity of thin films of our interest to 1) establish the base line comparison between vertical alignment and other orientations (horizontal alignment and amorphous films); 2) build the structure-property relation; and 3) understand the microscopic mechanisms by investigating the vibrational modes and quantifying the chain crystallinity and confinement. If the hypothesis is proven, this may open up exciting opportunities to engineer polymer-based thin films with high cross-plane thermal conductivity. The proposed study will advance the fundamental understanding of thermal transport in polymer-based thin films with vertical alignment or confinement, and answer whether the vertical alignment or confinement could potentially achieve high cross-plane thermal conductivity and how the enhancement, if any, can be optimized. The fundamental study of thermal transport processes in polymer-based thin films of this unique morphology highlights the intellectual merits of this work.