International Collaboration in Chemistry: Block Copolymers with Photocleavable Junctions

由阿默斯特马萨诸塞州大学的Edward Bryan Coughlin教授提出的ICC提案将得到MPS化学部有机和大分子计划内动力学组的支持。德国的协调人是有机化学研究所的帕特里克·西亚托博士和约亨·S·德国美因茨约翰内斯古滕贝格大学物理化学研究所。他们将得到德国研究基金会（DFG）的支持。嵌段共聚物，两种化学性质不同的聚合物在一端连接在一起，分离成与聚合物链的尺寸相当的域阵列（大约在10纳米长度尺度上）。从有序嵌段共聚物生成纳米多孔材料依赖于选择性去除一个嵌段而不损害基质材料的完整性。通过在嵌段共聚物的接合点处使用光可裂解单元，组分之一的去除将不取决于次要组分的化学性质，因此将适用于更大种类的嵌段共聚物。裂解的交界点光解后，然后通过选择性溶剂萃取去除的次要成分，因此是一个很有前途的策略，用于制备下一代的纳米多孔结构的嵌段共聚物。 在这项提案中，PI将开发合成方法，将邻硝基苄基酯或苯甲酰甲基酯作为嵌段共聚物中的光可裂解接头。 这些材料将使用有机合成和受控自由基聚合的组合来制备。 PI将系统地探索光解条件，这将导致在溶液状态下快速，清洁和有效的光裂解。 有了这个知识基础，他们将研究圆柱形或穿孔层状微相分离的薄膜和散装形态。 光裂解和选择性溶剂萃取去除次要组分将产生新的纳米多孔模板。 在如何生成纳米多孔模板或支架方面获得的知识将在许多不同的科学领域中具有未来的应用。 一系列新型嵌段共聚物的开发也将使他们能够探索广泛的基础聚合物物理化学研究，包括从快速创建的亚稳态的聚合物链扩散动力学。这将提供的可能性，调查从一个定义的微相分离的嵌段共聚物形态的两个不混溶的均聚物的宏观分离取决于先前的内切形态的转变。 这项化学国际合作计划将允许美国研究生在德国进行博士研究的关键部分。 研究合作加上学生的国际交流将创造一个未来的美国科学家和工程师的劳动力是全球参与，科学以及文化和社会。

This ICC proposal by Professor Edward Bryan Coughlin of the University of Massachusetts, Amherst, will be supported by the Dynamics group within the Organic and Macromolecular Program in the Chemistry Division of MPS. The German collborators are Dr. Patrick Theato, Institute for Organic Chemistry, and Professor Jochen S. Guttmann, Instutute for Physical Chemistry, Johannes Gutenberg University, Mainz. They will be supported by the Deutsche Forschungs Gesellshaft (DFG). Block copolymers, two chemically different polymers joined together at one end, separate into arrays of domains comparable to the dimensions of the polymer chains (approximately on the 10 nanometer length scale). The generation of nanoporous materials from ordered block copolymers relies on a selective removal of one block without compromising the integrity of the matrix material. By use of a photocleavable unit at the junction point of a block copolymer, the removal of one of the components will not depend on the chemical nature of the minor component and thus will be applicable to a much larger variety of block copolymers. Cleavage of the junction point upon photolysis, followed by removal of the minor components via selective solvent extraction, is thus a promising strategy for preparation of the next generation of nanoporous structures from block copolymers. In this proposal the PIs will develop synthetic methodologies to incorporate o-nitrobenzyl esters or phenacyl esters as photocleavable junctions in block copolymers. These materials will be prepared using a combination of organic synthesis and then controlled radical polymerizations. The PIs will systematically explore photolysis conditions that will lead to rapid, clean and efficient photocleavage in the solution state. With this knowledge base they will then study cylindrically or perforated lamellar microphase separated morphologies in thin films and in the bulk. Photocleavage and removal of the minor component by selective solvent extraction will thus yield novel nanoporous templates. The knowledge gained in how to generate nanoporous templates or scaffolds will have future applications in a number of different scientific fields. The development of a range of novel block copolymers will also allow them to probe a broad scope of fundamental polymer physical chemistry investigations involving polymer chain diffusion dynamics from rapidly created meta-stable states. This will provide the possibility to investigate the transformation from a defined micro-phase separated block copolymer morphology to a macroscopic separation of two immiscible homopolymers depending on the previously inscribed morphology. This International Collaboration in Chemistry proposal will allow United States graduate students to perform critical portions of their doctoral research in Germany. The research collaboration coupled with the international exchange of students will create a future US workforce of scientists and engineers that are globally-engaged, scientifically as well as culturally and socially.