Patterns of Hierarchical Molecular Self-Assemblies 2

• Applicant: Professor Dr. Motomu Tanaka
• Subject Area: Preparatory and Physical Chemistry of Polymers ; Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258513149

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.

• DFG Programme: Research Grants
• International Connection: France
• Participating Person: Professorin Dr. Marie Pierre Krafft