Opportunities in Block Copolymers: Reactive Rod/Coils and Magnetooptic Nanocomposites

所提出的研究将进一步推动嵌段共聚物进入更高价值的高科技应用领域，如化学图案化表面涂层、光刻掩模和改进的光学元件。为此，研究人员提出了两个广泛相关的基础研究领域：(1)用表面反应性棒/线圈两嵌段共聚物制造纳米材料；(2)用纳米粒子填充的嵌段共聚物制造可调磁光材料。在这两个项目中，PI以前在嵌段共聚物加工和结构-性能表征方面的经验将为在主体共聚物与基材和/或外加电场之间或主体聚合物与表面工程纳米颗粒之间建立结构和化学相互作用提供坚实的基础，从而决定所产生的纳米复合材料形态将允许获得新的和增强的物理性能。对如何最好地创建有序嵌段共聚体系的原理的更深入的洞察将对许多新兴技术具有广泛的适用性。关键是了解加工条件如何与化学结构相互作用以达到理想的最终状态，从而提供基于BCP的优质材料。棒状/盘状BCP及其与线团和棒状均聚物的混合物在很大程度上尚未被探索，这为了解液晶度在微相分离中的作用提供了机会。重点将放在棒/线圈共混物上，以研究棒BCP胶束，以及棒块上反应性基团的存在，以提供锁定形态结构、调节底物相互作用的手段，并创建合成的各向异性有机纳米对象，然后将其用作分级自组装的独特构建块。基于聚合物-无机材料的自组装纳米复合材料具有磁场可调的光学性质，通过空间模板将超顺磁性纳米颗粒组装到BCP中，可以得到自组装纳米复合材料。表面工程纳米粒子将被隔离在BCP中，由于其尺寸小(单域粒子)，应该会显示出比相应的块体材料更好的性能。通过选择一种具有足够分子质量的BCP，使得微区的周期性提供可见的波长光子禁带(PBG)，这些研究人员将制备出磁场可调的PBG材料。这种材料通过复合材料的场相关Verdet常数，具有作为偏振旋转器和光隔离器(“单向光阀”)的潜力。此外，纳米粒子-BDP形态的实验数据集将被用来与最近关于纳米粒子-BCP自组装几何的理论模型进行比较。该项目有几种影响社会的方式。研究生访问其他大学和工业的设想是让他们有更广泛的经验，以及获得新的仪器。PI有几个卓有成效的合作：C.Ober和S.Gruner(康奈尔大学)-嵌段共聚物合成和同步辐射(3-4名学生例行访问国际象棋和短期(一周)Ober实验室；S.Marel(Var-Llan，以色列)-纳米粒子合成(由于以色列目前的情况，还没有学生访问他的实验室)和B.Lotz Strasburg)--透射电子显微镜和电子衍射表征(对CNRS为期一个月的访问)。PI最近有共同创建初创企业的经验(Omni Guide Communications，Inc.)与另一位教授和一名前研究生一起，提供了如何将技术从大学转移到市场的视角。在过去的12年里，PI总共提交了15项专利披露，并已颁发了5项专利。此外，PI的小组一直在麻省理工学院招待几名被称为UROP的本科生。他们成功地参与了研究，几份出版物的合作证明了这一点。

The research proposed will further the possibility that block copolymers gain entry into higher value, high technology applications, such as chemically patterned surface coatings, lithographic masks and improved optical components. To this end, the investigator proposes two broadly related fundamental research areas: (1) creation of nanopatterns with surface-reactive rod/coil diblock copolymers and (2) fabrication of tunable magneto-optical materials from nanoparticle-filled block copolymers. In both these projects, the PI's previous experience with block copolymer processing and structure-property characterization will provide a firm base to build structure and chemical interactions between the host copolymer and a substrate and/or an applied field, or between the host polymer and surface engineered nanoparticles determines the resultant nanocomposite morphology will permit attainment of new and enhanced physical properties. Improved insight into the principles of how to best create ordered block copolymer based systems will have broad applicability to a host of emerging technologies. Key to this will be knowledge of how the processing conditions interplay with chemical structure to achieve desirable end states and thus afford superior materials based on BCPs.Rod/coil BCPs and their blends with both coil- and rod-homopolymers are largely unexplored and present an opportunity to learn about the role of liquid crystallinity on microphase separation. Emphasis will be on rod/coil - coil blends to investigate rod BCP micelles, and on the presence of reactive groups on the rod block to provide means for locking-in morphologics, for tuning substrate interaction, and to create synthetic anistropic organic nano-objects, which can then be employed as unique building blocks in hierarchical self assembly. Self assembled nanocomposites based on polymer-inorganic materials with magnetic field tunable optical properties will be produced by spatially templating superparamagnetic nanoparticles in BCPs. Surface engineering nanoparticles will be sequestered in the BCP and should display superior properties over the corresponding bulk materials due to their small size (single domain particles). By choosing a BCP that has sufficient molecular weight so that the microdomains' periodicity provides a visible wavelength photonic ban gap (PBG), these researchers will fabricate a magnetic field tunable PBG materials. Such materials have potential as polarization rotators and optical isolators ("one way light valves") via the field dependent Verdet constant of the composite. In addition, the experimental data set of nanoparticle-BDP morphologies will be used to compare to recent theoretical models of the geometry of nanoparticle-BCP self-assembly.This project has several ways to impact society. Visits of graduate students to other universities and to industry are envisioned to give them a broader experience, as well as to access to novel instrumentation. The PI has several highly productive collaborations: C. Ober and S. Gruner (Cornell) - block copolymer synthesis and synchrotron scattering (routine visits by 3-4 students to CHESS and short (one week) periods to Ober lab; S. Margel (Var-Llan, Israel) - nanoparticle synthesis (due to the present situation in Israel, no students have yet visited his lab) and B. Lotz Strasbourg) - TEM and electron diffraction characterization (month long visit to CNRS). The PI has recent experience co-founding a start up (Omni Guide Communications, Inc.) with another professor and a former graduate student, affording a perspective on how to undertake tech transfer from the university into the market place. Over the past 12 years, the PI has filed a total of 15 patent disclosures and 5 patents have been issued. In addition, the PI's group has always hosted several undergraduates, called UROPs, at MIT. Their successful participation in research is attested by co-authorzship of several publications.