Theory of nanostructured soft matter

了解结构物质的出现、稳定性和性质是科学和工程领域的一项努力，涵盖了从硬凝聚态物质中晶体的形成到生物系统中生物体的自组织等主题。该研究计划通过开发新的概念、理论框架和方法来研究由聚合物和胶体粒子等大分子自组装的纳米结构软物质，从而为这一努力做出贡献。该研究将使用嵌段共聚物作为主要模型系统。嵌段共聚物是通过将两个或多个化学性质不同的嵌段连接在一起而获得的，由于嵌段间的斥力和链连通性之间的竞争，从本质上讲，嵌段共聚物是不受欢迎的。类似的挫折发生在具有亲水和疏水成分的表面活性剂以及具有短程吸引和远程排斥相互作用的胶体颗粒中。这种挫败感驱使嵌段共聚物自组装成各种形状的纳米结构域，大致分为片层、圆柱体和球形。这些畴的堆积导致各种有序相的形成。嵌段共聚物形成各种有序纳米结构的能力为研究具有理想形态的软物质的出现、稳定性和性质提供了一个强大的平台。这种层次化的纳米结构聚合物材料可以有许多有用的应用，包括用于光子晶体的周期性有序软材料，用于药物输送的纳米级囊泡，以及用于下一代光刻的亚纳米模式。分层纳米结构软物质的形成涉及许多具有不同物理属性的成分，如分子大小、形状刚性和手性。这些组分之间的相互作用是复杂的，包括范德华力、氢键和静电相互作用。我将开发新的理论框架来一致地对待这些不同的属性，并将该理论应用于研究包含聚合物和非聚合物组分的软物质系统的自组装。提出的研究活动旨在阐明控制纳米结构软物质的出现和稳定性的原理。(1)计划研究嵌段共聚物共混物和分散嵌段共聚物等聚合物体系的相行为，重点研究通过不同聚合物的混合稳定新型复杂相；(2)计划研究树状大分子、胶体粒子等非聚合软物质体系中复杂球形堆积相的出现，重点了解软物质的普遍相行为；(3)计划研究不同有序相之间的过渡途径，重点了解纳米结构软物质的成核和生长机制。

Understanding the emergence, stability and property of structured matter is an endeavor in science and engineering covering topics ranging from the formation of crystals in hard condensed matter to the self-organization of living organisms in biological systems. The proposed research program contributes to this endeavor by developing new concepts, theoretical frameworks, and methodologies for the study of nanostructured soft matter self-assembled from macromolecules such as polymers and colloidal particles. The study will use block copolymers as a primary model system. Block copolymers, obtained by linking two or more chemically distinct blocks together, are intrinsically frustrated due to the competition between the inter-block repulsion and the chain connectivity. Similar frustration occurs in surfactants with hydrophilic and hydrophobic components and colloidal particles with short-range attractive and long-range repulsive interactions. The frustration drives block copolymers to self-assemble into nanodomains of various shapes, loosely classified as lamellae, cylinders and spheres. The packing of these domains leads to the formation of various ordered phases. The ability of block copolymers to form various well-ordered nanostructures provides a powerful platform to study the emergence, stability, and property of soft matter with desirable morphologies. The hierarchically nanostructured polymeric materials could have many useful applications, including periodically ordered soft materials for photonic crystals, nanosized vesicles for drug delivery, and sub-nanometer patterns for next-generation lithography. The formation of hierarchically nanostructured soft matter involves a number of components with diverse physical attributes such as molecular size, and shape rigidity, and chirality. The interactions between these components are complex including van der Waals force, hydrogen bonding and electrostatic interactions. I will develop new theoretical frameworks to treat these diverse attributes consistently and apply the theory to study the self-assembly of soft matter systems containing polymeric and non-polymeric components. The proposed research activities are designed to elucidate principles governing the emergence and stability of nanostructured soft matter. (1) I plan to study the phase behavior of polymeric systems such as block copolymer blends and disperse block copolymers, focusing on stabilizing novel complex phases via mixing of different polymers; (2) I plan to study the emergence of complex spherical packing phases in non-polymeric soft matter systems such as dendrimers and colloidal particles, focusing on understanding universal phase behavior of soft matter; (3) I plan to study the transition pathways connecting different ordered phases, focusing on understanding mechanisms of the nucleation and growth of nanostructured soft matter.