Fabrication of Freeform Hierarchical Micro/Nanostructures by Control of Capillary Interactions with Aligned Carbon Nanotubes

通过控制对齐碳纳米管的毛细管相互作用来制造自由分层微/纳米结构

• 批准号: 0927634
• 负责人: Anastasios John Hart
• 金额: $ 32万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2013-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0927634&HistoricalAwards=false
• 关键词: Fabrication; Freeform; Hierarchical; Micro; Nanostructures

Despite the excellent properties of individual carbon nanotubes (CNTs), their properties as assemblies are typically poor due to the low packing density even when they are self assembled to create vertically aligned ?forests? during growth. This renders current CNT forests inadequate for most MEMS device applications, and also largely prevents their compatibility with post-processing by traditional microfabrication. This project will overcome the barrier to use of CNTs in microfabrication by creating a new manufacturing process for robust and complex three dimensional microstructures made of aligned CNTs. This process consists of growth of CNT forests by thermal chemical vapor deposition, followed by controlled densification of the CNTs using capillary forces. Because capillary forces can infiltrate CNT forest microstructures individually, this process can create a wide variety of shapes in parallel. Building from our recent demonstration of this ?capillary forming? process, we will: (1) perform rigorous experiments on capillary forming of a library of archetypal CNT shapes, and relate the results to CNT structural characteristics in a nondimensionalized fashion; (2) create a finite element model that couples the free energy balance at a dynamic liquid-vapor interface to the deformation of a CNT forest, and compare the model results to experiments; (3) measure their mechanical properties of the freeform CNT structures by nanoindentation; and (4) create and test polymer-coated and metal-coated CNT cantilevers for application as anisotropic wetting surfaces and microspring contacts. Intellectual merit will result from our understanding of how to engineer robust freeform structures of CNTs, and more broadly of how a balance between surface tension and elastic forces governs the organization of fibrous networks. These insights will relate to self-assembly in natural systems and will be applicable to other nanostructured materials. We will connect our findings to broad audiences across multiple disciplines through: involvement of minority undergraduate and graduate students in research; a new undergraduate laboratory experiment involving CNT growth and capillary forming; and by creating structural models and exhibits in collaboration with artists and architects.

尽管单个碳纳米管（CNT）具有出色的特性，但由于堆积密度低，它们作为组件的特性通常很差，即使它们是自行组装以创建垂直对齐的森林？在生长期间。 这使得当前的CNT森林在大多数MEMS设备应用中不足，并且在很大程度上可以防止其与传统微加工后处理的兼容性。该项目将通过创建一个新的制造工艺来克服在微分化中使用CNT的障碍，以针对由Aligned CNT制成的稳健且复杂的三维微观结构。 该过程包括通过热化学蒸气沉积来生长CNT森林，然后使用毛细作用力控制CNT。 由于毛细管可以单独渗透CNT CNT森林微观结构，因此此过程可以并行产生各种形状。从我们最近对毛细血管形成的演示中建立？过程，我们将：（1）对原型CNT形状库的毛细管形成进行严格的实验，并以非量化的方式将结果与CNT结构特征相关联； （2）创建一个有限元模型，该模型将动态液体蒸气界面处的自由能平衡与CNT森林的变形相结合，并将模型结果与实验进行比较； （3）通过纳米构度测量自由形式CNT结构的机械性能； （4）创建和测试聚合物涂层和金属涂层的CNT悬臂，以应用作为各向异性润湿表面和微弹性接触。智力优点将是我们对如何设计CNT的强大自由形式结构的理解，以及更广泛地了解表面张力与弹性力之间如何平衡纤维网络的组织。 这些见解将与自然系统中的自组装有关，并适用于其他纳米结构材料。 我们将通过：少数学科和研究生参与研究的参与，将我们的发现与多个学科的广泛观众联系起来；一个新的本科实验室实验，涉及CNT生长和毛细血管形成；并通过与艺术家和建筑师合作创建结构模型和展览。