Patterned Polymer Brushes as the Basis of Shape Selected Molecular Objects

技术概述：本研究项目将研究二嵌段和三嵌段共聚物刷的合成、表征和光刻工艺。通过将刷状生长和自组装与精密图案相结合，将创造出各种新的聚合物微纳米结构，这些结构是其他方法难以生产的。提出的研究的一个关键方面是关注不混相块段组合，这种组合对光刻图版中使用的辐射有相反的反应。通过使用一个交联相和一个断裂相（很容易去除），新的周期结构、多孔材料、刷膜、纳米片和纳米带将形成。通过画笔的生长，组成和高度将被设定，通过图案的横向大小和形状将被确定。先进的图案化方法最初将包括电子束技术，随后将涉及深紫外处理。为了更快地评估电刷结构及其对图案形成的影响，将使用引发剂密度梯度和电刷段尺寸梯度。混合刷，二元刷和嵌段共聚物刷组成的交联和可剪段将进行研究。将使用各种分析工具，包括x射线反射仪，掠入射（GI） SAXS和WAXS，中子反射率和近边缘x射线吸收精细结构（NEXAFS）测量，对刷的图案前后进行表征。每种技术都将提供有关材料内部或表面组织的信息，并有助于我们理解所产生的结构。特别是中子反射率将提供有关电刷链构象的信息，因为电刷经历了图案化过程。几个模型系统将被调查，以更好地了解工艺限制和可能的架构，可以从这些刷子生产。混合梯度刷，支撑膜和无系留纳米片和纳米带将被探索。预计这些刷子的应用将包括用于水净化的新型膜，用于小型流体装置的纳米通道以及来自刷子梯度的新型纳米图案结构。非技术概述：聚合物刷是一种理想的结构，可以将材料表面与其环境连接起来。像许多天然表面一样，聚合物链从表面延伸出来，提供了一种有机涂层，其官能团可以被修改或用于许多应用。随着这些材料的系统合成和表征，有可能制造出具有梯度控制特性的刷状表面，能够包裹药物和其他有用材料以供稍后释放的纳米片，用于水净化的新膜，以帮助更好地改善干旱地区的饮用水，以及能够在传感器等小型设备中运输液体的纳米通道。该研究项目将作为一种机制，吸引本科生从事高分子科学和材料研究。研究生将作为这些年轻学生的导师和榜样，同时获得管理技能。研究生将有机会与我们的合作者的研究小组一起工作，并参加交流访问。康奈尔大学的本科生将在学年期间参加研究，而来自其他学校的REU学生将在夏季参加研究，重点是代表性不足的学生。参加这个项目的康奈尔大学本科生将被鼓励在我们将与之互动的公司和大学实验室实习。从这些研究项目中吸取的经验教训将被纳入PI和研究生志愿者与高中教师互动的项目中。有图案的刷子是有趣的视觉辅助工具，因为疏水刷子可以排斥水。对基板上的样品刷将提供给感兴趣的教师，PI将在康奈尔大学提供的教师研讨会上与他们会面。

TECHNICAL SUMMARY:This research program will examine the synthesis, characterization and lithographic processing of "grown from" di- and triblock copolymer brushes. By combining brush growth and self-assembly with precision patterning a variety of new polymer micro- and nanostructures will be created that are not easily produced by other means. A key aspect of the proposed research is a focus on immiscible block segment combinations that react in opposite ways to the radiation used during lithographic patterning. By using one phase that crosslinks and one that is scissioned (and easily removed), new periodic structures, porous materials, brush membranes, nanosheets and nanoribbons will be formed. Through brush growth the composition and height will be set and through patterning lateral size and shape will be determined. Advanced patterning methods will initially include electron beam techniques and will subsequently involve deep UV processes. In order to speed evaluation of brush architecture and its effect on pattern formation, the use of initiator density gradients and brush segment size gradients will be employed. Mixed brushes, binary brushes and block copolymer brushes consisting of crosslinkable and scissionable segments will be investigated. Characterization of the brushes before and after patterning will be made using a variety of analytical tools including X-ray reflectometry, grazing incidence (GI) SAXS and WAXS, neutron reflectivity and near edge X-ray absorption fine structure (NEXAFS) measurements. Each technique will provide information about the internal or surface organization of the material and will aid our understanding of the structures produced. Neutron reflectivity in particular will provide information about the brush chain conformation as the brush undergoes the patterning process. Several model systems will be investigated to better understand the process limitations and the possible architectures that can be produced from these brushes. Mixed gradient brushes, supported membranes and untethered nanosheets and nanoribbons will be explored. It is anticipated that applications for these brushes will include new membranes for water purification, nanochannels for small-scale fluidic devices and new nanopatterned strucures from brush gradients. NON-TECHNICAL SUMMARY:Polymer brushes are ideal structures to interface the surface of a material with its environment. Like many natural surfaces, polymer chains extend from a surface and provide an organic coating with functional groups that can be modified or used in a number of applications. Along with systematic synthesis and characterization of these materials, there are prospects for making brush surfaces with gradient controlled properties, nanosheets with the ability to wrap drugs and other useful materials for later release, new membranes for water purification to help better improve drinking water in arid regions and nanochannels that will enable transport of fluids in small devices such as sensors. The research program will act as a mechanism to engage undergraduates in polymer science and materials research. Graduate students will serve as mentors and role models to these young students, while at the same time gaining supervisory skills. Graduate students will have an opportunity to work with the research groups of our collaborators and to take part in exchange visits. Undergraduates from Cornell will take part during the academic year while REU students from other schools with an emphasis on underrepresented students will participate in research during the summer months. Cornell undergraduates taking part in this program will be encouraged to take internships at the companies and university labs we will interact with. Lessons learned from these research programs will be factored into programs in which the PI and graduate student volunteers interact with high school teachers. Patterned brushes make interesting visual aids because hydrophobic brushes can repel water. Sample brushes on substrates will be made available to interested teachers the PI will meet at teacher workshops offered by Cornell.