CAS: Sequence in Brush Copolymers

在化学系大分子、超分子和纳米化学项目的支持下，匹兹堡大学的塔拉·Y·迈耶教授正在制备具有二维序列控制的新型刷状共聚材料，并研究主链和侧链序列对水解降解曲线的联合影响。聚合物刷是一种大分子类型，其中主聚合链与不同密度的附加聚合链接枝。由于其紧凑和受限的结构，它们具有有用的性质，包括蠕虫状构象、致密的分子尺寸和显著的聚合物链端效应。因此，刷子是生物医学设备、化学传感器、药物输送系统和组织工程的很有前途的聚合物。在这项研究中，首先将利用化学反应来制备具有可生物降解和生物相容性的侧链的聚合物刷子，该侧链由不同序列的乳酸和乙醇酸组成。然后将所制备的刷子用于降解研究，目的是调查不同的刷子结构和侧链的2维序列对降解率的影响。与这项研究相关的活动旨在扩大参与范围，并使本科生和研究生能够接受聚合物化学、有机合成和催化方面的培训。与包括三所黑人大学(HBCU)在内的六个机构组成的宪章1 NOBCChE合作机构的互动，将继续侧重于培养成员之间的长期关系，目标是共同努力，支持来自代表性不足群体的学生在化学领域的成功和留住。这项研究将专注于控制含有可生物降解和生物相容的“阿尔法-羟基酸衍生”侧链的刷状共聚物的序列。在第一个目标中，我们将利用Ru催化的开环复分解聚合反应制备一维和二维序列控制降冰片烯基刷。通过优化乳酸和乙醇酸侧链的方法进行嫁接将得到利用。第二个目标将集中在具有二维顺序控制的环状刷子共聚物的合成和表征上，包括可以使用熵驱动聚合来开环以产生交替的刷子-线性多嵌段共聚物的变体。最后，将研究序列和结构对水解性降解率的综合影响，目的是发展对有序刷状共聚物中降解的机理的理解。与了解聚合物结构和降解之间的相互作用相关的基础研究有可能导致基于刷子的药物输送载体的改进设计。此外，与这项研究相关的刷线状多嵌段共聚物的合成和表征可能会影响需要具有组织性质的聚合物的应用。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 Tara Y. Meyer of the University of Pittsburgh is preparing novel brush copolymer materials with 2-dimensional sequence control and studying the combined effects of both backbone and sidechain sequence on the hydrolytic degradation profiles. Polymer brushes are type of macromolecules in which the main polymer chain is grafted with additional polymer chains of varying density. They have useful properties including wormlike conformations, compact molecular dimensions, and notable polymer chain-end effects due to their compact and confined structures. As such, the brushes are promising polymers for biomedical devices, chemical sensors, drug-delivery systems, and tissue engineering. In this research, chemical reactions will first be used to prepare polymer brushes with biodegradable and biocompatible side chains consisting of different sequences of lactic and glycolic acids. The prepared brushes will then be utilized in degradation studies with the aim to investigate the effects of different brush architectures and 2-dimensional sequences of side chains on the degradation rate. The activities associated with this research are designed to broaden participation and enable training of undergraduate and graduate students in polymer chemistry, organic synthesis, and catalysis. The interactions with a Charter 1 NOBCChE collaborative consisting of six institutions, including three historically black colleges & universities (HBCUs), will continue to focus on fostering long-term relationships among members with the goal of working together to support the success and retention of students from underrepresented groups in chemistry.This research will focus on controlling sequences in brush copolymers containing biodegradable and biocompatible "alpha-hydroxy acid derived" sidechains. In the first objective, one- and two-dimensional sequence controlled norbornene based brushes will be prepared using ruthenium catalyzed ring-opening metathesis polymerization. Grafting through methodology optimized for lactic and glycolic acids side chains will be utlized. The second objective will focus on the synthesis and characterization of cyclic brush copolymers with two-dimensional sequence control including variants that can be ring-opened using an entropy-driven polymerization to create alternating brush-linear multiblock copolymers. Lastly, the combined effects of sequence and architecture on hydrolytic degradation rates, with the goal of developing a mechanistic understanding of the degradation in sequenced brush copolymers, will be investigated. Fundamental studies related to understanding of the interactions between polymer architecture and degradation have the potential to lead to improved design of brush-based drug delivery vehicles. Additionally, the synthesis and characterization of the brush-linear multiblock copolymers associated with this research could impact applications that require polymers with tissue-like 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.