Patterned Polymer Brushes as the Basis of Shape Selected Molecular Objects

技术概述：本研究项目将研究从二嵌段和三嵌段共聚物刷生长的合成、表征和光刻处理。通过将刷子生长和自组装与精密图案化相结合，将创造出各种用其他方法不易制造的新的聚合物微结构和纳米结构。拟议研究的一个关键方面是关注不混溶的块段组合，这些组合以相反的方式对光刻图案期间使用的辐射产生反应。通过使用一种交联相和另一种容易去除的相，将形成新的周期性结构、多孔材料、刷膜、纳米片和纳米带。通过刷子生长来设定成分和高度，通过图案来确定横向尺寸和形状。先进的图案化方法最初将包括电子束技术，随后将涉及深紫外光工艺。为了加快对刷子结构及其对图案形成的影响的评估，将使用引发剂密度梯度和刷子段大小梯度。将研究由可交联段和可裂解段组成的混合刷子、二元刷子和嵌段共聚刷子。将使用各种分析工具对图案化前后的刷子进行表征，包括X射线反射仪、掠入射(GI)SAXS和WAXS、中子反射率和近边X射线吸收精细结构(NEXAFS)测量。每种技术都将提供有关材料内部或表面组织的信息，并有助于我们对所产生的结构的理解。尤其是当刷子经历图案化过程时，中子反射率将提供有关刷子链构象的信息。将对几个模型系统进行调查，以更好地了解过程限制和可以从这些画笔产生的可能架构。将探索混合梯度刷子、支撑膜和无绳纳米片和纳米带。预计这些刷子的应用将包括用于净水的新型膜、用于小型流体设备的纳米通道以及基于刷子梯度的新型纳米结构。非技术摘要：聚合物刷子是将材料表面与环境相连接的理想结构。与许多天然表面一样，聚合物链从表面延伸，并提供具有官能团的有机涂层，这些官能团可以在许多应用中进行改性或使用。除了这些材料的系统合成和表征外，还有望制造具有梯度控制性能的刷子表面，能够包裹药物和其他有用材料以供以后释放的纳米片，有助于更好地改善干旱地区饮用水的新型净水膜，以及能够在传感器等小型设备中实现流体传输的纳米通道。该研究计划将作为一种机制，吸引本科生从事聚合物科学和材料研究。研究生将成为这些年轻学生的导师和榜样，同时获得监督技能。研究生将有机会与我们的合作者的研究小组合作，并参与交流访问。来自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学生将在夏季几个月参与研究，重点是代表性不足的学生。参加该项目的康奈尔大学本科生将被鼓励到我们将与之互动的公司和大学实验室实习。从这些研究项目中学到的经验教训将被纳入到项目中，在这些项目中，PI和研究生志愿者与高中教师互动。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。基板上的样本画笔将提供给感兴趣的教师，国际学生联合会将在康奈尔大学提供的教师研讨会上开会。

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.