Collaborative Research: Fundamentals of Block Copolymer Ordering During Cold Zone Annealing

技术综述：通过热区退火法对嵌段共聚(BCP)薄膜进行非平衡处理有望克服传统热力学方法的巨大挑战，为高科技应用创造无缺陷和长程有序的功能薄膜。热区退火包括在薄膜平面上传递移动的热温度梯度，以局部熔化和固化薄膜。最近，一种低温“冷区退火”或CZA版本被展示出来，并取得了令人振奋的结果。由于大多数嵌段共聚物在高于熔点的显著高温下会降解，CZA广泛适用于许多嵌段共聚体系。CZA在玻璃圆柱体上形成PS-PMMA嵌段共聚物膜的结果表明，CZA在增强的有序化动力学和取向方面高达一个数量级。基于这些有希望的结果，CZA驱动的BCP有序化现象背后的关键分子机制将在基础水平上进行研究。这项研究将使用不同的嵌段共聚体系来研究CZA的这些基本方面，以阐明CZA诱导嵌段共聚薄膜体系有序化的一般规则。该研究计划的一个重要组成部分依赖于CZA中嵌段共聚物有序化的活化能分析，该分析来自CZA的颗粒尺寸生长或关联长度发展，作为CZA速度、最高温度和梯度大小参数以及BCP相对分子质量和嵌段相互作用参数的函数。此外，还将使用图案化和非图案化的衬底来阐明定向排列的起源和机制。非技术摘要：嵌段共聚材料在过去十年中一直是关注的焦点，作为从功能光子材料到兆比特密度数据存储设备等广泛新兴纳米技术需求的潜在解决方案。然而，使用这些材料的主要限制是存在缺陷。这项提议将寻求了解新的退火台的基本原理，该退火台可以显著降低消除缺陷的障碍。这些基本原理可能导致新的加工技术，从而在许多与工业相关的领域取得进展。PI的学生将在阿贡国家实验室的高级光子源获得经验，允许在国家研究设施进行曝光和培训。这项研究的一个积极组成部分旨在通过阿克伦大学早期高中计划和中学后远程学习机会计划，以及阿克伦圣文森特圣玛丽高中和聚合物科学与工程学院之间的一个新计划，让邻近高中的学生参与进来，学生和教师都参与其中。此外，这项研究将让少数族裔和女性参与他们的研究项目，阿克伦大学和阿肯色大学小石城分校都以其少数族裔和女性在研究项目中的高比例而闻名。此外，UALR的这项研究项目将通过一项名为奋力的计划，在暑期邀请中学理科教师参加。让教师接触这项研究，包括合成和纳米表征，将提高他们的科学技能以及他们对该领域的理解，使他们成为更好的教育者。

TECHNICAL SUMMARY: Non-equilibrium processing of block copolymer (BCP) thin films via thermal zone-annealing promises to overcome significant challenges of traditional thermodynamic approaches to create defect free and long-range ordered functional films for high-tech applications. Thermal zone annealing involves passing a moving thermal temperature gradient across the plane of the film to locally melt and solidify the film. Recently a low temperature "cold zone annealing" or CZA version was demonstrated with promising results. Since most block copolymers will degrade at significantly high temperatures above melt point, CZA is broadly applicable to many block copolymer systems. Results for CZA on glassy cylinder forming PS-PMMA block copolymer films indicate up to an order of magnitude in enhanced ordering kinetics and alignment. Based on these promising results, key molecular mechanisms underlying the CZA driven ordering phenomena for BCPs will be examined at a fundamental level. This research will investigate these fundamental aspects of CZA using different block copolymers systems to illuminate general governing principles of CZA induced ordering of block copolymer thin film systems. An important component of the research plan relies on an Activation Energy analysis of ordering of block copolymer in CZA from grain size growth or correlation length development as a function of CZA parameters of velocity, maximum temperature, and gradient magnitude and the BCP molecular weight and block-block interaction parameter. In addition, the origin and mechanism of orientational alignment will be elucidated using both patterned and non-patterned substrates.NON-TECHNICAL SUMMARY:Block copolymer materials have been the focus over the last decade as potential solutions to a wide range of emerging nanotechnology needs from functional photonic materials to terabit density data storage devices. The major limitation to the use of these materials, however, is the presence of defects. This proposal will seek to understand the fundamentals of a new annealing platform that significantly reduces the barrier to defect removal. These fundamentals could lead to new processing techniques allowing advances in many industrially relevant fields. The PI's students will get experience at the Advanced Photon Source at Argonne National Lab allowing for exposure and training at national research facilities. An active component of the research is aimed at involving students at adjacent high-schools through the Akron Early College High School program as well the Post Secondary Distance Learning Opportunities and through a new program between St. Vincent St. Mary's High School in Akron and the College of Polymer Science and Engineering involving both students and teachers. In addition, the research will involve minority and women participation in their research program and both the University of Akron and University of Arkansas at Little Rock are both well known for their high ratio of minorities and women in research programs. In addition, this research project at UALR would incorporate secondary high school science teachers during the summer through a program known as STRIVE. The exposure of the teachers to this research including synthesis and nanocharacterization would improve their science skills as well as their understanding of the field making them better educators.