Iterative Macromolecular Functionalization

在化学系大分子、超分子和纳米化学项目的支持下，约翰霍普金斯大学的Rebekka Klausen正在开发一种单一的合成平台，可以获得传统原料无法直接聚合的大分子。化学转化将首先用于制备沿主骨架含有碳硼键的聚合物和共聚物。然后合成的大分子将通过将这些键转化为相应的醇、氯化物和简单的α -烯烃而多样化。这些历史上难以获得的聚合物的合成有望揭示新的结构-功能关系，并能够系统地评估这些系统的物理，机械和化学性质。此外，由于所制备的聚合物将包含极性和非极性功能，期望改善附着力和氧渗透性。这两种性质在与商业塑料相关的几种应用中都非常重要。约翰霍普金斯大学和三一华盛顿大学（华盛顿特区的一所少数族裔服务机构和女子学院）之间的暑期本科生卓越研究（SURE）项目的参与，将使少数族裔和第一代本科生在聚合物科学研究方面得到培训。与聚合物科学和可持续性相关的额外推广和教育活动将在马里兰州奥尔尼的一所大学预科高中进行，该高中拥有多元化的学生群体。该项目将侧重于开发新的聚合物改性化学物质，使用硼烷取代的聚烯烃作为前体，以获得难以获得的（co）聚合物。具体来说，由烯丙基单体（如氯丙烯和烯丙醇）以及丙烯衍生的共聚物的合成将采用mattson同源法，然后进行氢化、氧化和/或氯代酰化。通过mattson同源性将亚甲基或氯甲基插入碳硼键是有机硼烷化学的一个特别引人注目的应用，因为它可以迭代和立体定向应用，同时产生很少的副产物。这项研究的目标是烯丙醇、氯丙烯和α -烯烃的（co）聚合物；由于竞争性链转移、催化剂中毒或反应性比例不匹配，无法直接从烯丙基单体聚合中获得的难以捉摸和高度期望的聚合物材料。这项工作所合成的聚合物有望为与合成有机和聚合物群落相关的系统结构-性能研究开辟新的化学空间。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Rebekka Klausen of Johns Hopkins University is developing a single synthetic platform that will access macromolecules that cannot be made by direct polymerization of traditional feedstocks. Chemical transformations will first be utilized to prepare polymers and copolymers containing carbon-boron bond along the main backbone. The synthesized macromolecules will then be diversified by converting these bonds to corresponding alcohols, chlorides and simple alpha-olefins. The synthesis of these historically inaccessible polymers is expected to uncover new structure-function relationships and enable systematic evaluation of physical, mechanical, and chemical properties of these systems. Additionally, since the prepared polymers will contain polar and nonpolar functionalities, improved adhesion and oxygen permeability is expected. Both properties are very important in several applications or relevance to commercial plastics. The involvement in the Summer Undergraduate Research Excellence (SURE) program between Johns Hopkins University and Trinity Washington University, a minority-serving institution and women’s college in Washington, DC, will enable training of minority and first-generation undergraduate students in polymer science research. Additional outreach and educational activities related to polymer science and sustainability will be conducted at a college preparatory high school with a diverse student body in Olney, Maryland.This project will focus on the development of new polymer modification chemistries using borane-substituted polyolefins as precursors to access (co)polymers that are otherwise difficult to obtain. Specifically, the synthesis of copolymers that are formally derived from allylic monomers such as allyl chloride and allyl alcohol, as well as propene, will be conducted using Matteson homologation followed by hydrogenative, oxidative, and/or chlorinative deborylation. The insertion of a methylene or chloromethyl group into a carbon–boron bond via Matteson homologation is a particularly compelling application of organoborane chemistry because it can be applied iteratively and stereospecifically, while yielding few byproducts. This research is targeting (co)polymers of allyl alcohol, allyl chloride, and alpha-olefins; polymers that are elusive and highly desired materials that cannot be accessed directly from polymerization of allylic monomers due to competitive chain transfer, catalyst poisoning, or mismatched reactivity ratios. Polymers synthesized as a result of this work is anticipated to open up new chemical space for systematic structure-property studies of relevance to the synthetic organic and polymer communities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.