Computational and Experimental Design of Associating Bottle Brush Mesostructures

有了这个奖项，化学系的大分子，超分子和纳米化学项目资助了道格拉斯H。康涅狄格大学的Adamson和Elena Dormidontova研究了在介观尺度下定义明确的聚合物结构的行为。 中尺度物质的特征长度介于纳米尺度（蛋白质、DNA、病毒）和宏观尺度（细菌、染色体、人类头发）之间，通常表现出与更大或更小长度尺度不同的相互作用和性质。 在介观尺度上，物质不仅通过小分子中的化学键结合在一起，而且还通过额外的缔合力和解离力或相互作用结合在一起。 许多生物学都是在中尺度上通过这些额外的键合相互作用来运作的。 例子包括蛋白质折叠，病毒包囊，软体动物外壳的形成，和细胞膜之间的运输。 在这项研究中，使用化学反应来制备聚合物刷或蠕虫状分子，其中主聚合物链接枝有不同密度的附加聚合物链。这些侧聚合物链含有不同的缔合基团，包括DNA链和可以结合金属的小分子。 计算机建模和各种其他测量技术，然后用于预测，指导和表征组装聚合物刷在中尺度。 对更广泛的社会的好处包括有可能加速开发基于受控和可预测的中尺度结构的无机/有机和生物启发材料。 人力资源和培训的好处出现通过本科生和研究生的多样化群体的培训，以及通过化学奇才计划的支持。 化学奇才计划与高中生在代表性不足的人群，并使用基于竞争的方法，以提高对STEM为基础的职业生涯的兴趣。在计算机建模的指导下，这项研究正在开发独特的构建块介观组装。 聚合物瓶刷功能化的不同的关联基团，包括DNA链和配体的金属配体络合与不同的密度和分布的关联基团，系统地制备使用的组合建立和修改的合成方法。 瓶刷聚合物的自组装的特点和研究使用透射电子显微镜和散射的方法，以及通过蒙特卡罗和粗粒度的分子动力学模拟。 瓶刷架构（刚性，接枝长度，分布和密度的官能团），协会的强度，和性质的官能团相互作用（自相互作用和互补组装）的动态和结果的自组装溶液中的效果也进行了系统的研究。 这项工作解决了许多有关聚合物材料组装在介观尺度上的挑战，包括缺乏理论框架，理解集体相互作用和运动的差距，结构出现，建模和测量亚稳态的挑战，以及在实验上控制这些状态的困难。 与该奖项相关的成果可能对开发用于生物学、医学和材料化学的新型聚合物结构有价值。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。

With this award, the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry is funding Professors Douglas H. Adamson and Elena Dormidontova at University of Connecticut to study the behavior of well-defined polymeric structures at the mesoscale. Matter at the mesoscale, with characteristic length between the nanoscale (proteins, DNA, viruses) and macroscale (bacteria, chromosomes, human hair) typically exhibit fundamentally different interactions and properties than at larger or smaller length scales. At the mesoscale, materials are held together not only by the chemical bonds found in small molecules, but by additional associative and dissociative forces or interactions. Much of biology operates at the mesoscale with these additional bonding interactions. Examples include protein folding, virus encapsulation, mollusk shell formation, and transport between cellular membranes. In this research, chemical reactions are used to prepare polymer brushes or worm-like molecules in which the main polymer chain is grafted with additional polymer chains of varying density. These side polymer chains contain different associating groups, including DNA strands and small molecules that can bind metals. Computer modeling and a variety of other measurement techniques are then used to predict, guide and characterize assemblies of polymer brushes at the mesoscale. Benefits to the broader society include the potential for accelerated the development of inorganic/organic and bioinspired materials based on controlled and predictable mesoscale structures. Human resource and training benefits arise through the training of a diverse group of undergraduate and graduate students, as well as through the support of the Chemistry Wizards program. The Chemistry Wizards program works with high school students in under-represented populations and uses a competition-based approaches to increase interest in STEM-based careers.Guided by computer modeling, this research is developing unique building blocks for mesoscopic assembly. Polymer bottlebrushes functionalized by different associating groups, including DNA strands and ligands for metal-ligand complexation with different densities and distributions of associating groups, are systematically prepared using a combination of established and modified synthetic approaches. Self-assemblies of bottlebrush polymers are characterized and studied using transmission electron microscopy and scattering approaches, as well as by Monte Carlo and coarse-grained Molecular Dynamics simulations. The effect of bottlebrush architecture (rigidity, length of grafts, distribution, and density of functional groups), association strength, and nature of functional group interaction (self-interaction and complementary assembly) on the dynamics and outcomes of self-assembly in solution are also systematically investigated. This work addresses many challenges pertaining to polymeric materials which assemble at the mesoscale, including lack of theoretical framework, gaps in understanding collective interactions and motions from which structures emerge, challenges in modeling and measuring metastable states, and difficulty in controlling these states experimentally. Results associated with this award could be valuable in the development of novel polymeric structures for biology, medicine, and materials 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.