Mechanically Entwined Double Helical Covalent Polymers

在化学学部大分子、超分子和纳米化学项目的支持下，科罗拉多大学博尔德分校的张伟教授将开发新的合成策略，以形成长双螺旋的聚合物，类似于自然产生的DNA（2'-脱氧核糖核酸）和胶原蛋白。本研究旨在了解决定聚合物折叠、缠绕和自组装成双螺旋结构的关键参数，这种结构可能表现出独特的材料性能。拟议的工作将作为一个平台，为教育、外联和少数民族在多个层面的参与提供新的机会。研究生和本科生将接受包括有机、超分子、聚合物化学和纳米科学在内的多学科研究培训。一段时间以来，化学家们一直试图制造出能与自然界生物大分子相媲美的分子。然而，合成高分子量的共价键聚合物，形成延伸的双螺旋，类似于自然发生的DNA和胶原蛋白，仍然是一个巨大的挑战。本研究的目标是开发具有稳定而动态的共价键的螺旋聚合物的合成策略，了解双螺旋共价聚合物（HCP）的形成过程，并建立HCP的一般设计原则。制备一系列具有不同物理尺寸、不同电子密度分布和不同反应位点数量的刚性芳环基构建块，研究单体结构对HCP形成的影响。此外，在过去的三十年中，形成双螺旋的唯一策略是操纵两个单链亚基之间的二次吸引相互作用（双工键）。相比之下，本文提出的新型化学-机械杂化键方法（重点是间双键）可能为设计和合成高阶功能聚合物结构（包括双螺旋聚合物及其组件）开辟了许多新的可能性。这个新系统将提供一个替代的简单模型来研究线性聚合物的结构和它们组装成双螺旋结构的潜力之间的关系。它还提出了(i)线性聚合物折叠，（ii）超分子缠绕和（ii）手性传播的新平台。更具体地说，在后一种情况下，将探讨通过引入手性诱导剂形成手性螺旋聚合物的可能性。高电荷、长螺旋聚合物晶体的电子和机械性能的各向异性可以用于未来开发具有不同于天然生物聚合物和生物系统的性能的新型纳米材料。该奖项反映了美国国家科学基金会的法定使命，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 the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Wei Zhang of the University of Colorado-Boulder will develop novel synthetic strategies for polymers that form long double helices, similar to naturally occurring DNA (2'-deoxyribonucleic acid) and collagen. This research aims to understand the critical parameters determining the folding, winding, and self-assembly of the polymers into double helical structures, which may exbibit unique materials properties. The proposed work will serve as a platform for providing new opportunities for education, outreach, and minority involvement on multiple levels. Graduate and undergraduate students will be trained in multidisciplinary research involving organic, supramolecular, polymer chemistry, and nanoscience.Chemists have been trying to build molecules that can rival the sophistication of Nature’s biomacromolecules for some time. However, synthesis of high molecular weight covalently bonded polymers that form extended double helices, similar to naturally occurring DNA and collagen, still represents a grand challenge. The goals of this research are to develop novel synthetic strategies for helical polymers connected with robust yet dynamic covalent linkages, to understand the double helical covalent polymer (HCP) formation process, and to establish a general design principle for HCPs. A series of rigid aromatic ring-based building blocks with varied physical dimensions, varied distribution of electron density, and varying number of reactive sites will be prepared to study the effect of monomer structure on HCP formation. Moreover, the only strategy of forming double helices over the past three decades has been maneuvering secondary attractive interactions between the two single-stranded subunits (intra-duplex bonding). By contrast, the novel chemical-mechanical hybrid bonding approach proposed herein (focused on inter-duplex bonding) may open up many new possibilities for the design and synthesis of higher order functional polymeric architectures, including double helical polymers and their assemblies. This new system would offer an alternative simple model to study the relationship between the structures of linear polymers and their potential to assemble into a double helix. It also suggests novel platforms for (i) linear polymer folding, (ii) supramolecular intertwining, and (ii) chirality propagation. More specifically, in the latter case, the possibility of forming chiral helical polymers by introducing chiral inducers will be explored. The anisotropy of electronic and mechanical properties of the highly-charged, long helical polymer crystals being targeted may be exploitable for the future development of novel nanoscale materials with properties that are distinct from those of native biopolymers and biosystems.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.