Collaborative Research: Polymer Single Crystal-Assisted "Grafting From": A Versatile Approach towards Multicomponent Polymer Brushes with Well-Defined Architectures and Grafting

材料的表面性能对其应用至关重要（例如，胶带的粘合性能、防水服装的不湿性能和炊具的不粘表面）。通常，材料表面需要进行化学修饰以适应其性能。在这项合作研究中，田纳西大学诺克斯维尔分校的赵斌教授和德雷塞尔大学的克里斯托弗·李教授开发了一种可行的方法，可以用含有明确结构的聚合物修饰表面，从而实现对表面结构和性能的精确控制。这一基础化学研究有望推动聚合物科学领域的发展，并为材料和技术的发展提供新的机遇。该项目的其他更广泛的影响包括教育和培训聚合物化学和物理方面的本科生和研究生，为聚合物（塑料）行业准备劳动力。聚合物化学被整合到面向高中教师和学生的拓展活动中（例如，德雷克塞尔大学暑期拓展项目中的“泡沫和黏液形成”等演示实验），以激发他们对科学的兴趣。美国国家科学基金会化学部的大分子、超分子和纳米化学项目支持这项研究，以开发一种强大而通用的策略，用于在平坦的固体衬底（例如硅晶片和玻璃衬底）上制备各种定义良好的多组分聚合物刷。本研究旨在结合聚合物单晶辅助的“接枝到”和表面引发的“活的”/控制聚合（即“接枝从”），合成具有复杂结构的刷子，如y形和环，以及可调的接枝密度。采用开环聚合、原子转移自由基聚合、氮氧基自由基聚合等多种聚合方法合成了多组分聚合物毛刷。一系列技术（如原子力显微镜、x射线光电子能谱、扫描和透射电子显微镜、掠射小角x射线散射和广角x射线衍射）被用来表征聚合物刷的结构和性能。

The surface properties of a material can be critical to its application (e.g., the adhesive properties of tapes, non-wetting properties of water-repellent garments, and non-stick surface of cookware). Often, the material surface needs to be chemically modified to tailor its properties. In this collaborative research, Professor Bin Zhao of the University of Tennessee Knoxville and Professor Christopher Li of Drexel University develop a viable method for modifying a surface with a polymer containing a well-defined architecture and thus achieving precise control of surface structures and properties. This fundamental chemistry research is expected to advance the field of polymer science and present new opportunities in materials and technology development. Additional broader impacts of the project include education and training of undergraduate and graduate students in both polymer chemistry and physics, preparing a workforce for the polymer (plastics) industry. Polymer chemistry is integrated in outreach activities (e.g., demonstration experiments such as "Foam and Slime Forming" in a Drexel summer outreach program) for high school teachers and students to arouse their interests in science. The Macromolecular, Supramolecular and Nanochemistry Program of the NSF Chemistry Division supports this research to develop a robust and versatile strategy for preparing a variety of well-defined multicomponent polymer brushes on flat solid substrates (e.g., silicon wafers and glass substrates). This research aims to combine polymer single crystal-assisted "grafting to" and surface-initiated "living"/controlled polymerization (i.e., "grafting from") to synthesize brushes with complex architectures, such as Y-shape and loop, and tunable grafting densities. Various polymerization methods (including ring-opening polymerization, atom transfer radical polymerization, and nitroxide-mediated radical polymerization) are used to synthesize the multicomponent polymer brushes. A range of techniques (e.g., atomic force microscopy, x-ray photoelectron spectroscopy, scanning and transmission electron microscopies, grazing incident small-angle X-ray scattering, and wide angle X-ray diffraction) are used to characterize the polymer brush structures and properties.