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

材料的表面性质对于其应用可能是至关重要的（例如，胶带的粘合性能、防水服装的不润湿性能和炊具的不粘表面）。 通常，材料表面需要进行化学改性以调整其性能。 在这项合作研究中，田纳西州诺克斯维尔大学的赵斌教授和德雷克塞尔大学的克里斯托弗·李教授开发了一种可行的方法，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，并为材料和技术发展提供新的机遇。 该项目的其他更广泛的影响包括在聚合物化学和物理方面对本科生和研究生进行教育和培训，为聚合物（塑料）行业准备劳动力。 聚合物化学被纳入外联活动（例如，示范实验，如德雷克塞尔暑期推广计划中的“泡沫和粘液形成”），以激发高中教师和学生对科学的兴趣。NSF化学部的大分子、超分子和纳米化学计划支持这项研究，以开发一种稳健和通用的策略，用于在平坦的固体基底上制备各种定义明确的多组分聚合物刷（例如，硅晶片和玻璃衬底）。 本研究旨在将联合收割机聚合物单晶辅助“接枝到”和表面引发的“活性”/受控聚合（即，“接枝自”）来合成具有复杂结构（如Y形和环）和可调接枝密度的刷。 各种聚合方法（包括开环聚合、原子转移自由基聚合和氮氧自由基聚合）被用来合成多组分聚合物刷。 一系列技术（例如，原子力显微镜、X射线光电子能谱、扫描和透射电子显微镜、掠入射小角X射线散射和广角X射线衍射）来表征聚合物刷结构和性能。

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.