Patterns of Hierarchical Molecular Self-Assemblies 2

该项目的主要目标是通过对分子层级结构形成的机理的理解，在二维平面薄膜和三维微泡中设计新的分子自组装系统模式。这是一个合成高氟化两亲化合物和自组装胶体体系的氟碳化学小组(Leader，Marie Pierre Krafft)和一个软物质物理小组(Leader，Motomu Tanaka)共同努力的成果，该小组专注于界面纳米薄膜的表征。高度氟化的两亲分子自组装成直径几十纳米的单分散盘状结构域，在2D和3D体系中形成高度有序的六角阵列。该项目的最终目标是在大小和组织方面控制和优化这些独特的表面图案，以便在3D系统中利用它们，例如带有包含这种自组装纳米域的外壳的微泡。为了实现这一目标，我们提出了两个具体目标。首先，我们将研究平面薄膜，如朗缪尔单分子膜、朗缪尔-布洛吉特膜和旋涂多层膜，它们由含氟化合物与碳氢两亲化合物(如磷脂和聚合物)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1)表面区内分子的层级有序性的影响，以及2)膜内区之间的相关性，以及3)表面区对薄膜力学的影响。所获得的结果将被用于调整不同长度尺度(从几微米到亚微米)的磁畴的大小和有序性，从而控制机械性能。其次，我们将制备稳定的、窄分布的微泡，并赋予一个包含在2D薄膜中研究和优化的纳米结构域的外壳。由于全氟烷基磷酸盐在水分散体系中形成可持续数周的微泡，因此有可能研究两亲分子的分子结构及其分级自组装对微泡的稳定性、回声、产生谐波的能力和机理的影响。将这一战略从2D系统扩展到3D系统(乳液和气泡)，使其具有具有动态、压力响应特性的柔软和灵活的外壳，这是一项从未被接受的重大科学挑战。应该强调的是，借助表面敏感技术对2D薄膜中的分层结构形成的机理的理解为优化系统提供了最有效的途径。从实用的角度来看，这一概念将为诊断和治疗微泡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.