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。微结构超疏水表面可以保留气囊，在水和船体之间起到气体润滑的作用。虽然对超疏水表面的研究已有近20年的历史，但直到最近，周期性的线性沟槽结构才被证明对在代表海洋、海洋和湖泊的开阔水域航行的海洋船只是有效的。这种定义明确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。这些硅工艺的成本高得令人望而却步，而且不能扩展到大面积的表面，如船体。为了应对这些挑战，来自北卡罗来纳州立大学和加州大学洛杉矶分校的一个团队希望利用以低成本和大规模生产而闻名的辊涂方法在大型基板上形成周期性微结构。这一新工艺的研究是为了开发船体减摩涂层，并研究其物理和化学耐久性。因此，这项研究的成果将有利于广泛的海洋应用，包括在国家和全球经济和安全应用中发挥重要作用的商业和军用船舶。该项目研究了滚涂过程中聚合物表面的自发图案生成，采用了一种全新的方法在大面积衬底上制造三维微米和纳米结构。其目的是为控制滚涂过程中形成的微观组织提供科学依据，并制作和验证在现实的开阔水域和雷诺数大于100万的流动条件下表面的减阻效果。研究小组将利用计算建模来预测实验观察证实的粘弹性聚合物的变形行为。为了在真实流动中验证减阻的概念，将在摩托艇底部铺设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培养下一代工程师和科学家。研究成果还将用于通过各种形式教育K-12、本科生和研究生，如外展活动和创新课程努力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.