CAREER: Photomodulation of Polymer Molecular Weight Distribution

职业：聚合物分子量分布的光调制

• 批准号: 1945271
• 负责人: Melanie Chiu
• 金额: $ 67.5万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1945271&HistoricalAwards=false
• 关键词: CAREER; Photomodulation; Polymer; Molecular; Weight

With this CAREER Award from the Macromolecular, Supramolecular and Nanochemistry Program in the Chemistry Division, Professor Melanie Chiu at Stony Brook University in New York is developing a new method for controlling polymer dispersity using light to mediate the chemical reactivity of polymer chain-ends. Polymers, long chains of small molecular units called monomers, are essential and ever-present in our everyday lives, from industrially-manufactured plastics, to naturally occurring cellulose in plants and plant-derived materials, like cotton. The material properties of such polymers, including stiffness, melting temperature, electrical conductivity, and degradation profile are often affected by the polymer’s dispersity, or the uniformity of the molecular chain lengths within a given sample. Controlling polymer dispersity—whether the chains are of similar or dissimilar lengths—is a promising means of tailoring a polymer’s physical properties without changing its molecular structure. This research is developing a one-pot system in which the polymerization initiator is turned on or off with light. This photo-switch results in two states: one that yields low dispersity polymers and another one that yields high dispersity polymers. Once these polymers are made, the research project features studies on how different reaction parameters affect optimize the dispersities that can be accessed. The second part of the research project focuses on systematically studying how polymer dispersity affects polymer properties. While these efforts focus on specific types of polymers, polyvinyl ethers, the last research activity expands the concept of using light to control polymer chain-end reactivity to form other types of polymers. Results associated with this award have the potential to significantly impact various fields of science and engineering where molecular control over polymer properties is of interest. Professor Chiu fosters integration of research and education by developing curriculum materials in collaboration with the New York State Master Chemistry Teacher's program to enhance the education of high school chemistry students throughout New York State.The research is focused on establishing a deterministic method for photoswitchable regulation of polymer dispersity and its applications to block copolymer synthesis by photochemically manipulating the rate of chain propagation versus deactivation of the chain-end in controlled cationic vinyl ether polymerizations. The project features the development of photochromic Bronsted acid initiators that yield polymers with low dispersity in one photoisomeric state, and high dispersity in the other photoisomeric state. In the first objective, the mechanism by which the carboxy-functionalized dithienylethenes enable photocontrol over polymer dispersity in cationic vinyl ether polymerizations is studied, and a comprehensive kinetic model is constructed to guide further optimization of the system. The second objective focuses on the application of the carboxy-functionalized dithienylethene initiators to the synthesis of block copolymers and investigation of their materials properties. The final objective expands the concept of externally manipulating relative rates of chain propagation and chain-end deactivation to achieve control over dispersity in other types of controlled polymerization reactions. The chemistry in this work expands the repertoire of polymerization reaction parameters that can be externally modulated and enables a better understanding of how dispersity influences polymer properties.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.

纽约斯托尼布鲁克大学的Melanie Chiu教授获得了化学系大分子、超分子和纳米化学项目的职业奖，她正在开发一种利用光来调节聚合物链端的化学反应性来控制聚合物分散性的新方法。 聚合物，即称为单体的小分子单元的长链，在我们的日常生活中是必不可少的，从工业制造的塑料到植物中天然存在的纤维素和植物衍生材料，如棉花。 这种聚合物的材料性质，包括刚度、熔融温度、电导率和降解曲线，通常受到聚合物的分散性或给定样品内分子链长度均匀性的影响。控制聚合物的分散性--无论链的长度是相似还是不同--是在不改变聚合物分子结构的情况下定制聚合物物理性质的一种有前途的方法。 本研究开发了一种一锅体系，其中聚合引发剂用光打开或关闭。 这种光开关产生两种状态：一种产生低分散性聚合物，另一种产生高分散性聚合物。 一旦这些聚合物制成，该研究项目的特点是研究不同的反应参数如何影响优化可以获得的分散性。研究项目的第二部分着重于系统地研究聚合物分散性如何影响聚合物性能。虽然这些努力集中在特定类型的聚合物，聚乙烯醚，最后的研究活动扩展了使用光来控制聚合物链端反应性的概念，以形成其他类型的聚合物。 与该奖项相关的结果有可能对科学和工程的各个领域产生重大影响，其中对聚合物性能的分子控制是感兴趣的。 赵教授与纽约州化学硕士教师计划合作开发课程材料，促进研究与教育的融合，以提高整个纽约州高中化学学生的教育。研究重点是建立一种确定性方法，用于光开关调节聚合物分散性，并通过光化学控制链增长速率将其应用于嵌段共聚物合成相对于在受控阳离子乙烯基醚聚合中链端的失活。该项目的特点是开发光致变色布朗斯台德酸引发剂，该引发剂在一种光异构状态下具有低分散性，而在另一种光异构状态下具有高分散性。在第一个目标中，羧基官能化的二噻吩基乙烯，使光控制聚合物的分散性在阳离子乙烯基醚聚合的机制进行了研究，并构建了一个全面的动力学模型，以指导系统的进一步优化。第二个目标是将羧基官能化的二噻吩基乙烯引发剂应用于嵌段共聚物的合成及其材料性能的研究。最后的目标扩展的概念，外部操纵的相对速率的链增长和链端失活，以实现控制在其他类型的受控聚合反应的分散性。这项工作中的化学扩展了聚合反应参数的范围，这些参数可以进行外部调节，并使人们能够更好地了解分散性如何影响聚合物性能。该奖项反映了NSF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。

项目成果

A general model for the ideal chain length distributions of polymers made with reversible deactivation

• DOI: 10.1039/d1py01331a
• 发表时间: 2022-01-07
• 期刊: POLYMER CHEMISTRY
• 影响因子: 4.6
• 作者: Kearns, Madison M.;Morley, Colleen N.;Konkolewicz, Dominik
• 通讯作者: Konkolewicz, Dominik