Collaborative Research: Template-Free Manufacturing of Regular Microstructures by Ribbing-Enhanced Roll Coating

一项能够减少船体摩擦或阻力的技术将通过提高燃料效率而产生重大的经济和环境影响。微结构化的超疏水表面可以保持气穴，所述气穴可以用作水和船舶船体之间的气体润滑。虽然超疏水表面已经研究了近二十年，但直到最近才证明周期性线性沟槽结构对在开放水域（代表海洋，海洋和湖泊）中航行的海洋船只有效。这种良好限定的微沟槽的制造依赖于基于半导体制造方法的硅基微制造。这些硅工艺非常昂贵，并且不能扩展到大的表面积，例如船体。为了应对这些挑战，来自北卡罗来纳州州立大学和加州大学洛杉矶分校的一个团队希望利用辊涂方法，这是众所周知的成本效益和大规模生产，以形成大基板上的周期性微结构。本研究旨在开发船体减摩涂料，并对其物理化学耐久性进行研究。因此，这项研究的成果将有利于广泛的海洋应用，包括商业和军用船舶，这些船舶在国家和全球经济以及安全应用中发挥着重要作用。该项目研究了在辊涂过程中聚合物表面以有序的方式通过肋状结构自发产生的图案，使用一种全新的方法在大面积基底上制造三维微米和纳米级结构。其目的是建立科学的基础，以控制在辊涂过程中形成的微观结构，并制造和验证的表面在开放的水和雷诺数大于100万的实际流动条件下的减阻效率。研究团队将利用计算建模来预测经过实验观察验证的粘弹性聚合物的变形行为。为了在实际流动中进行减阻的概念验证，将在摩托艇的底部分层微结构薄膜和光滑薄膜，专门配备以可靠地比较两者上的流体剪切应力。该项目将通过涉及制造，材料科学，计算建模和流体力学的多学科研究来教育下一代工程师和科学家。研究成果也将用于教育K-12，本科生，以及研究生水平的学生，通过各种形式，如外展活动和创新课程的努力。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

A technology that can reduce the friction or drag on ship hulls would have a substantial economic and environmental impact by improving fuel efficiency. Microstructured superhydrophobic surfaces may retain air pockets that can act as gas lubrication between the water and the ship hull. Although the superhydrophobic surfaces have been studied for nearly two decades, it is only recently that periodic linear-trench structures have been shown to be effective for marine crafts traveling in open water, which represents sea, oceans, and lakes. The manufacturing of such well-defined micro-trenches has relied on silicon-based microfabrication based on semiconductor manufacturing approaches. These silicon processes are prohibitively expensive and not scalable for large surface areas, such as ship hulls. To address these challenges, a team from North Carolina State University and University of California at Los Angeles would like to utilize roll coating methodology, which is well known for cost-effective and large-scale production, to form the periodic microstructures on large substrates. This new process is researched to develop friction-reduction coatings for ship hulls and study their physical and chemical durability. Hence, outcomes from this research will benefit a wide array of marine applications, including commercial and military ships, which play a significant role in the national and global economies and security applications. This project is investigates the spontaneous pattern generation by ribbing on polymer surfaces during roll coating in an ordered manner using a fundamentally new approach to manufacture three-dimensional micro and nano-scale structures on a large-area substrate. The objectives are to establish the scientific foundation to control the microstructures formed during the roll coating, and to fabricate and validate the drag reduction efficiency of the surfaces in realistic flow conditions of open water and Reynolds number greater than 1 million. The research team will utilize computational modeling to predict the deformation behavior of the viscoelastic polymer verified by the experimental observations. For the proof-of-concept of drag reduction in realistic flows, a microstructured film and a smooth film will be layered on the bottom of a motorboat specifically outfitted to reliably compare the fluid shear stresses on the two. This project will educate the next generation of engineers and scientists through multidisciplinary research involving manufacturing, materials science, computational modeling, and fluid mechanics. The research outcome will be also used to educate K-12, undergraduate, as well as graduate-level students through various formats such as outreach activities and innovative curricular efforts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.