Selective Fundamental Problems in Supramolecular Assembly and Phase Stability of Homopolymer Mixtures

芝加哥大学的卡尔·弗里德得到了化学理论、模型和计算方法计划颁发的研究自组装和相关现象的奖项的支持。平衡自组装是化学、材料科学和生物学中普遍存在的一种现象，它涉及分子自发地组织成更大的结构，显示出秩序。因此，控制这种自组装的能力在工业和医学上有许多应用。通过平衡自组装形成的大量复杂的功能结构表明，对潜在原理的理解可以在设计真正新颖的材料和医疗疗法时产生革命性的影响。这推动了对合成自组装系统的大量高级实验研究，如纳米颗粒、多肽和DNA络合物，发展了用于合成大分子体系的转化策略，合成具有特定性质的超分子体系，以及计算机模拟分子和更大尺度粒子的自组装。最后是当前项目的工作重点。自组装分析模型的快速发展有望推动应用向前发展，因为人们学习利用自然长期使用的丰富的原理来创建高度响应和功能的自组织和自我修复材料。这些进展可以极大地提高对软物质、纳米技术、生物技术、医学等不同问题的认识，当扩展到非平衡自组装时，可以解决基本过程，如生命系统的发展和细胞运动和通信。目前的提议代表了一项长期研究计划的高潮，该计划致力于发展预测均聚物混合物和含有可相互缔合或与溶剂缔合的物种的溶液的热力学性质的基础理论。这两种类型的缔合在化学平衡时都会导致形成大小可变的团簇。理论方法要么基于Flory-Huggins(FH)理论对自组装的扩展，要么基于更详细的晶格团簇理论(LCT)，该理论包括对FH理论忽略的分子特征的描述，如单体大小和形状、链刚性和可压缩性效应。LCT最近被扩展到描述强相互作用的遥螺旋聚合物(带有粘性端基的聚合物)的溶液。该理论旨在阐明生命系统中许多结构上重要的结合过程的一般效应，这些过程受到周围链、限制表面和结合分子(例如，调节组装稳定性的蛋白质)的很大影响。相互缔合、聚合物溶解性和疏水性的共同一般机制强调了所提出的溶剂化/结合研究的基本性质。竞争性分子结合在洗脱层析、材料合成和生物过程中也具有重要意义。这项拟议的研究勾勒出了一个广泛的理论框架，用于开发理论，帮助合理设计新材料、新药物系统和物理疗法，以减轻与自我组装故障相关的疾病。

Karl Freed at the University of Chicago is supported by an award from the Chemical Theory, Models and Computational Methods Program to study self-assembly and related phenomena. Equilibrium self-assembly involving the spontaneous organization of molecules into larger structures that show order is a ubiquitous phenomenon pervading chemistry, materials science, and biology. Hence, the ability to control this self-assembly has numerous applications for industry and medicine. The vast array of complex functional structures formed through equilibrium self-assembly suggests that an understanding of the underlying principles can be transformative in designing truly novel materials and medical therapies. This has motivated numerous advanced experimental studies of synthetic self-assembling systems such as nanoparticles, peptides and DNA complexes, the development of transformative strategies for synthesis of macromolecular systems, the synthesis of supramolecular systems with specific properties, and computer simulations of the self-assembly of molecular and larger-scale particles. The last is a focus of the work in the current project. The rapid growth of analytical modeling of self-assembly promises to drive applications forward as one learns to exploit the rich palette of principles, long utilized by nature, to create highly responsive and functional self-organizing and self-healing materials. These advances can greatly improve knowledge concerning diverse problems in soft matter, nanotechnology, biotechnology, medicine, and, when extended to non-equilibrium self-assembly, allow addressing basic processes such as the development of living systems and cell locomotion and communication. The current proposal represents the culmination of a long term research program devoted to developing fundamental theories for predicting thermodynamic properties of homopolymer mixtures and of solutions containing species that can associate with each other or with solvent. Both types of association lead at chemical equilibrium to the formation of clusters of variable size. The theoretical approaches are based either on extensions of Flory-Huggins (FH) theory to self-assembly or on the more detailed lattice cluster theory (LCT), which includes a description of molecular features neglected by FH theory, such as monomer size and shape, chain stiffness, and compressibility effects. The LCT has recently been extended to describe solutions of strongly interacting telechelic polymers (polymers with sticky end groups). The theory aims at elucidating the generic effects of many structurally important binding processes in living systems that are greatly influenced by surrounding chains, confining surfaces, and binding molecules (e.g., proteins that modulate the stability of assemblies). The common general mechanism of mutual association, polymer solubility and hydrophobicity stresses the fundamental nature of the proposed studies of solvation/binding. Competitive molecular binding is also of central significance in elution chromatography, materials synthesis, and biological processes. The proposed research outlines a broad theoretical framework for developing theories that can assist in the rational design of new materials, new drug systems, and physical therapies to mitigate against diseases associated with malfunctioning self-assembly.