Ordered Mesoporous Materials with Closed Pores

具有闭孔的有序介孔材料

• 批准号: 0907487
• 负责人: Michal Kruk
• 金额: $ 18.58万
• 依托单位: CUNY College of Staten Island
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0907487&HistoricalAwards=false
• 关键词: Ordered; Mesoporous; Materials; Closed; Pores

NON-TECHNICAL DESCRIPTION: A grand challenge in materials chemistry is to control the structure and properties of materials at nanoscale. One of the focal points in the effort to meet this challenge is the ability to introduce well-defined nanoscale voids (pores) in the structure of materials. While the last two decades brought milestones in the design of materials with accessible (open) nanopores, advances in the development of materials with closed (isolated) nanoscale pores were limited, even though the latter materials are of significant interest in electronics industry as low-dielectric-constant on-chip insulating media in integrated circuits. The current project is focused on exploring a predictive way to synthesize closed-pore materials, which is based on the use of surfactant micelles as templates to generate well-defined pore arrays. The surfactant templating has revolutionized the synthesis of nanoporous materials, but because of the need to remove the surfactant template from the pores, it seemed to be inherently suitable for open-pore rather than closed-pore architectures. Recently, the micelle-templating approach to generate closed-pore materials was developed which was based on identifying conditions at which the template is removed before the pores close. The current research effort is focused on extending the scope of this powerful approach on new material compositions and on achieving more beneficial structural properties of the closed-pore materials. Thus, the project will provide a knowledge base for the development of closed-pore materials with designed structures and properties and is expected to benefit a broad range of scientists and engineers that study and apply porous materials. The project involves postdoctoral fellows, graduate students and undergraduate students, with a special focus on minority undergraduate students.TECHNICAL DETAILS: This work will explore a new and transformational approach to the synthesis of well-defined materials with closed (isolated) nanopores, which is based on recently discovered thermally-induced pore closure phenomenon in micelle-templated mesoporous materials. This process promises to be a predictive pathway for the synthesis of closed-pore nanoporous silicas and is expected to be applicable for organosilicas. Ways to obtain silicas and organosilicas with closed spherical pores of diameter 5 nm or lower, which are most appropriate in applications as low-k materials, are being explored. Materials that exhibit the pore closure at as low temperatures as possible (preferably around 300°C) are sought. Ways to achieve the thermally-induced pore closure with minimized extent of shrinkage will be delineated. Periodic mesoporous organosilicas, which are inherently more suitable than silicas for low-k applications due to their lower bulk dielectric constant, are being explored as closed-pore materials candidates. Ways to increase the pore volume of closed-pore materials, thus reducing the dielectric constant, are being developed. Synthetic pathways to materials with closed cylindrical pores are being explored. The study focuses on samples in powder form due to the lack of readily accessible facilities to characterize thin films, but conclusions of the study are expected to extend to materials in the thin-film form. The project will generate the knowledge base for the synthesis of closed-pore nanoporous materials with tailor-made framework composition, pore size, pore shape and pore volume. This effort contributes to the current quest to overcome limitations in the processing speed of electronic devices by exploring a new avenue to the low dielectric constant materials. The project involves the training of scientists and students in the synthesis and characterization of cutting-edge nanoscale materials.

非技术描述：材料化学中的一个重大挑战是在纳米尺度上控制材料的结构和性能。努力迎接这一挑战的焦点之一是在材料结构中引入定义明确的纳米级空洞(气孔)的能力。虽然在过去的二十年里，具有可接近(开放)纳米孔的材料的设计取得了里程碑，但具有封闭(隔离)纳米孔的材料的开发进展是有限的，尽管后者作为集成电路中的低介电常数片上绝缘介质在电子工业中引起了极大的兴趣。目前的项目集中在探索一种可预测的合成闭孔材料的方法，该方法基于使用表面活性胶束作为模板来生成定义良好的孔阵列。表面活性剂模板法使纳米多孔材料的合成发生了革命性的变化，但由于需要将表面活性剂模板从孔中移除，它似乎固有地适合于开孔而不是闭孔结构。最近，胶束模板法制备闭孔材料的方法被开发出来，该方法是基于识别在孔闭合之前模板被移除的条件。目前的研究工作集中在扩大这一强有力的方法在新材料组成上的范围，并获得更有利的闭孔材料的结构性能。因此，该项目将为开发具有设计结构和性能的闭孔材料提供知识基础，并有望使研究和应用多孔材料的广泛的科学家和工程师受益。该项目涉及博士后、研究生和本科生，特别关注少数族裔本科生。技术细节：这项工作将探索一种新的、变革性的方法来合成具有封闭(孤立)纳米孔的明确材料，该方法基于最近发现的胶束模板化介孔材料中的热诱导孔闭合现象。该工艺有望成为合成闭孔纳米多孔二氧化硅的一条可预测的途径，并有望应用于有机硅。人们正在探索获得直径为5 nm或更小的闭合球形孔的二氧化硅和有机硅的方法，这些方法最适合作为低k材料应用。寻找在尽可能低的温度下(最好在300℃左右)表现出气孔闭合的材料。将描述如何在最小程度收缩的情况下实现热诱导的气孔闭合。周期性介孔有机硅由于其较低的体介电常数而比二氧化硅更适合于低k应用，作为闭孔材料的候选材料正在被探索。增加闭孔材料的孔体积，从而降低介电常数的方法正在开发中。人们正在探索合成具有闭合圆柱孔的材料的途径。由于缺乏易于获取的设备来表征薄膜，研究的重点是粉末形式的样品，但研究的结论预计将延伸到薄膜形式的材料。该项目将为合成具有量身定制的骨架组成、孔尺寸、孔形状和孔体积的闭孔纳米多孔材料生成知识库。这一努力有助于目前通过探索低介电常数材料的新途径来克服电子设备处理速度的限制。该项目涉及对科学家和学生进行尖端纳米材料的合成和表征方面的培训。