Elucidating Ring Opening Metathesis Copolymerization Thermodynamics of Monomers with Dissimilar Ring Strain Energies

在化学系大分子、超分子和纳米化学项目的支持下，佛罗里达州立大学的Justin G.Kennemur教授正在研究环单体在开环歧化聚合(ROMP)中的共聚热力学。将两个或两个以上的单体共聚为一个大分子或聚合物提供了一种生产社会塑料的不同方法，这些社会塑料包含各种应用的分布功能。具体地说，ROMP使用成熟的催化剂，通过应变环烯烃单体的链生长，提供了各种工业上相关的聚烯烃材料。Kennemur团队将进行系统的合成、动力学和机械研究，以了解基本热力学原理以及催化剂和溶剂等关键条件如何最终决定各种环烯烃共单体的竞聚率及其在生长的大分子链中的排序。该项目还将引入新的基于生物质的萜烯类环烯烃，以提供ROMP中常用的环烯烃单体所不具备的中环应变的热力学光谱。研究团队将继续与美国化学学会第一个聚合物化学分会和聚合物材料科学与工程分会学生分会合作，该分会是由佛罗里达农业和机械大学(FAMU)的一所历史上的黑人学院/大学和佛罗里达州立大学的一所R1研究型大学共同建立的。这一学生章节将汇集以聚合物科学研究为目标的高度不同的学生和教职员工。这一独特的平台还将被用来促进研究生和本科生向领导力的发展，这既是由外联管理的，也是以聚合物科学为中心的佛罗里达州新会议的发展。该项目将专注于阐明具有不同环应变能的单体的开环歧化共聚热力学。在第一个目标中，将使用现代综合方法来确定对其环应变能(RSE)的微小变化高度敏感的低应变环戊烯单体的竞聚率。根据热力学原理(单体浓度、化学计量比和温度)，确定的参数将与聚合物微结构中的单体测序相关。第二个目标将检测Delta-Pinene及其变体apopinene，它们的RSE介于ROMP中通常使用的高应变和低应变单体之间。此外，还将探讨这些萜类单体之间以及与低/高RSE单体之间的基础热力学研究和共聚反应。最后，最后一个具体目标将通过研究高应变和低应变单体的组合来限制RSE之间的差异。这类研究具有交替和块状测序策略的潜力。综上所述，这些研究有可能为从现成的环烯烃单体合理设计共聚物提供指导原则；有可能揭示适用于一般开环聚合(ROMP)的基本原理，从而对聚合物化学产生重大的长期科学影响。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, Professor Justin G. Kennemur of Florida State University is studying copolymerization thermodynamics of cyclic monomers in ring opening metathesis polymerization (ROMP). Copolymerization of two or more individual monomers into one macromolecule or polymer offers a divergent means of producing societal plastics that contain distributed functionality for a myriad of applications. Specifically, ROMP affords a variety of industrially relevant polyolefin-based materials through chain growth of strained cycloolefin monomers using well-established catalysts. This Kennemur team will perform systematic synthetic, kinetic and mechanistic studies to gain understanding of how basic thermodynamic principles along with key conditions, such as catalyst and solvent, ultimately dictate the reactivity ratios of various cycloolefin comonomers and their sequencing within the macromolecular chains that are grown. The project will also introduce new biomass-based terpene cycloolefins to provide a thermodynamic spectrum of medium ring-strain not afforded by the commonly employed cycloolefin monomers in ROMP. The research team will continue engagement with the first ever American Chemical Society Division of Polymer Chemistry and Division of Polymer Materials Science and Engineering student chapter that is co-established between a historically black college/university of Florida Agricultural and Mechanical University (FAMU) and an R1 research university in Florida State University. This student chapter will bring together a highly diverse body of students and faculty aimed at polymer science research. This unique platform will additionally be utilized to promote the growth of graduate and undergraduate students towards the development of leadership, both governed by outreach and the development of a new Florida-based conference, centered on polymer science.This project will focus on elucidating ring opening metathesis copolymerization thermodynamics of monomers with dissimilar ring strain energies. In the first aim, reactivity ratios of low-strain cyclopentene monomers that are highly sensitive to slight variations in their ring strain energy (RSE) will be determined using modern integrated approaches. Determined parameters will then be correlated to monomer sequencing within the polymer microstructure as a function of thermodynamic principles (monomer concentration, stoichiometry, and temperature). The second aim will examine, delta-pinene, and its variant, apopinene , which have RSEs that are in-between the high strain and low strain monomers typically employed in ROMP. Fundamental thermodynamic investigations and copolymerizations of these terpene-based monomers with each other and with low/ high RSE monomers will also be explored. Finally, the last specific aim will push the limits of disparity between RSEs by investigating high strain and low strain monomers in combination. Such investigations have potential for both alternating and blocky sequencing strategies. Taken together, these studies have the potential to provide guiding principles for the rational design of copolymers from readily available cycloolefin monomers; there is the potential to uncover basic principles that will apply to ring-opening polymerization (ROMP), in general, and thereby have a significant long-term scientific impact on polymer chemistry.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.