Patterns of Hierarchical Molecular Self-Assemblies 2

该项目的主要目的是通过对其分层结构形成的机理理解，在二维平面薄膜和三维微泡中设计分子自组装系统的新模式。这是一个氟碳化学小组（领导，Marie Pierre Krafft）和软物质物理小组（领导，Motomu Tanaka）的合作成果，他们合成了高度氟化的两亲体和自组装的胶体系统，专注于界面处纳米化薄膜的表征。高度氟化的两亲体自组装成单分散的圆盘状结构域，直径为几十纳米，在二维和三维系统中形成高度有序的六边形阵列。该项目的最终目标是在尺寸和组织方面控制和优化这些独特的表面模式，以便在3D系统中利用它们，例如带有由这种自组装纳米畴组成的外壳的微泡。为实现这一目标，我们提出两个具体目标。首先，平面薄膜，如Langmuir单层膜，Langmuir- blodgett和自旋涂覆多层膜，由氟化化合物与碳氢化合物两亲体（如磷脂和聚合物）混合的表面结构域组成的纳米结构。特别强调的是确定分子结构对以下方面的影响：1)表面区域内分子的等级顺序；2)膜内区域之间的相关性；3)表面区域对膜力学的影响。所获得的结果将用于调整不同长度尺度（从几个Å到亚微米）的结构域的大小和顺序，从而控制机械性能。其次，我们将制备稳定的、狭窄分散的微气泡，并赋予其壳层，其中包含在二维薄膜中研究和优化的纳米结构域。由于全氟烷基化磷酸盐在水分散体中形成的微泡可以持续数周，因此有可能研究两亲分子结构及其分层自组装对微泡稳定性、回声性、产生谐波的能力和力学的影响。将该策略从2D系统扩展到3D系统（乳剂和气泡），这些系统具有柔软、灵活的外壳，具有动态、压力响应特性，这是一项前所未有的重要科学挑战。需要强调的是，借助表面敏感技术对二维薄膜中分层结构形成的机理理解是优化系统的最有效途径。从实际的角度来看，这一概念将为微泡诊断和治疗的发展提供重大进展。

The primary aim of the proposed project is to design novel patterns of molecular self-assembled systems in two-dimensional planar films, as well as in three-dimensional microbubbles, by the mechanistic understanding of their hierarchical structure formation. This is a collaborative effort of a Fluorocarbon Chemistry group synthesizing highly fluorinated amphiphiles and self-assembled colloidal systems (leader, Marie Pierre Krafft) and a Soft Matter Physics group (leader, Motomu Tanaka) focusing on the characterization of nanopatterned films at the interface. Highly fluorinated amphiphiles are self-assembled into monodisperse, disk-like domains with a diameter of several tens of nanometers, forming highly organized hexagonal arrays in both 2D and 3D systems. The ultimate goal of the project is to control and optimize these unique surface patterns in terms of size and organization in order to exploit them in 3D systems, such as microbubbles with a shell comprising such self-assembled nanodomains. To achieve this goal, we propose two specific aims. First, planar thin films, such as Langmuir monolayers, Langmuir-Blodgett and spin-coated multilayers, nanostructured by surface domains of fluorinated compounds mixed with hydrocarbon amphiphiles (e.g. phospholipids and polymers) will be investigated. Special emphasis will be to determine the impact of molecular structures on the hierarchical ordering of 1) molecules within surface domains and 2) correlation between domains within the films, and 3) impact of the surface domains on the film mechanics. The obtained results will be utilized to tune the size and ordering of domains at different length scales (from a few Å up to sub-microns), and thus to control the mechanical properties. Second, we will prepare stable, narrowly dispersed microbubbles bestowed with a shell containing the nanodomains studied and optimized in 2D films. As perfluoroalkylated phosphates form microbubbles that can last for weeks in aqueous dispersions, it is possible to investigate the impact of the molecular structure of the amphiphiles and their hierarchical self-assembly on the stability, echogeneicity, aptitude at generating harmonics and mechanics of the microbubbles. The extension of the strategy from 2D systems to 3D systems (emulsions and bubbles) with soft and flexible shells possessing dynamic, pressure-responding properties is an important scientific challenge that has never been taken up. It should be emphasized that the mechanistic understanding of the hierarchical structure formation in 2D films with aid of surface-sensitive techniques provides with the most effective way to optimize the systems. From a practical standpoint, this concept will offer major advances in the development of microbubbles for diagnosis and therapy.