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正在开发一个单一的合成平台，可以访问传统原料无法直接聚合的大分子。首先将利用化学转化制备沿主链含有碳-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，并能够对这些体系的物理、机械和化学性质进行系统的评估。此外，由于所制备的聚合物将包含极性和非极性官能团，因此有望改善附着力和透氧性。这两种性能在几个应用中或与商业塑料相关时都非常重要。约翰霍普金斯大学和三一华盛顿大学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获得聚合物科学研究方面的培训。三一华盛顿大学是一所为少数群体服务的机构，位于华盛顿特区的女子学院。与聚合物科学和可持续性有关的其他外展和教育活动将在马里兰奥尔尼的一所大学预科高中进行，学生群体多样。该项目将侧重于开发新的聚合物改性化学，使用硼烷取代的聚烯烃作为获得(Co)聚合物的前体，否则很难获得(Co)聚合物。具体地说，从烯丙基单体(如烯丙基氯和烯丙醇)以及丙烯中正式衍生的共聚物的合成将使用Matteson同系化，然后进行氢化、氧化和/或氯代脱氧反应。通过Matteson同源反应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地应用，同时产生的副产物很少。这项研究的目标是烯丙醇、烯丙基氯和α-烯烃的(共同)聚合物；这些聚合物是难以捉摸的、非常理想的材料，由于竞争性链转移、催化剂中毒或不匹配的竞聚率，无法直接从烯丙基单体聚合中获得。作为这项工作的结果合成的聚合物有望为与合成有机和聚合物社区相关的系统结构-性质研究开辟新的化学空间。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.