Self-assembly

self assembly DNA

In nature, order, complexity and patterns are formed spontaneously through bottom up organization of specific local interactions. A process called self-assembly. This section groups EPFL’s research projects that use these principals, especially at the molecular level, to create complex structures and materials.

Self-assembly for 1D and 2D Nanostructures of Organic Electronic Materials

Organic nanowires are model systems for the investigation of charge transport in organic semiconductors under nanoscopic confinement, and may serve as potential building blocks for integrated circuits in the future. However, reliable structure-property relationships between the molecular parameters, the intermolecular π–π interactions, the nature of the charge carriers, and macroscopic transport properties are scarce. We have developed a reliable model system for the self-assembly of various chromophores into well-defined nanowires with excellent π–π overlap of the chromophores. These nanowires exhibit an unprecedented light-induced “self-doping”, resulting in exceptionally high charge densities and band-like transport properties.

Research Lab: prof Holger Frauenrath, Laboratory of Macromolecular and Organic Materials

 

Biologically-inspired hybrid block copolymers

Our research activities focus on conjugates of synthetic polymers and biologically-inspired peptide sequences. The peptide sequences are adapted from protein structures and direct the structure formation of the synthetic polymer. The use of such peptide sequences offers several unique advantages. First of all, due to the very specific folding and organization properties of the peptide sequences, they allow the organization of synthetic polymers in complex, hierarchically-organized structures that are very difficult to generate otherwise. Secondly, the structure and properties of peptide – synthetic hybrid block copolymers can be manipulated by single amino acid “mutations” in the peptide segments (see Strucutre page). The peptide sequence of the hybrid block copolymers cannot only be used to drive structure formation, but can also be used to encode specific functionalities. This is a subject of ongoing research efforts.

Research Lab: prof Harm-Anton Klok, Polymers Laboratory

 

Structural Self-assembly of Origami Robots, Robogamis

While Origami, the traditional Japanese art of paper folding, is primarily known for its artistic significance, many of its components can be found in nature. From insect wings to different types of leaves, organisms take advantage of the ability to create thin and lightweight structures by folding quasi-two-dimensional elements in distinct patterns. At the Reconfigurable Robotics Lab, RRL, we are developing robots that mimic and enhance the benefits of Origami found in nature. Our robots incorporate quasi-two-dimensional smart structures with embedded actuation, sensing, control, and communication, allowing them to change both shape and functionality according to the task at hand. By automating these structural transformations and functional reconfigurations, we are creating versatile robotic systems that are compact for storage and transportation and, when deployed, can self-assemble into lightweight, three-dimensional tools.

Research Lab: prof. Jamie Paik, Reconfigurable Robotics Lab
 

Functionally graded antimicrobial surfaces

In nature a vast diversity of functions rely on graded architectures, with continuous spatial changes of composition and morphologies. Synthetic functionally graded materials represent one of the many novel integrative and bio-inspired strategies as alternatives to conventional polymer processing and soft chemistry routes to produce hybrid organic/inorganic composites hierarchically organized in terms of structure and functions. Based on the principles of functionally graded properties and self-assembly, we created antibacterial surfaces with outstanding activity. These surfaces are made of graded polymer composites with controlled concentration profiles of photocatalytic Fe3O4@TiO2 core–shell nanoparticles. A photo-magnetophoretic process was invented to generate these surfaces. We also produced super-hard polymer-based surfaces, graded permittivity insulators and low stress coatings using this technique.

Reference: Nardi T., Rtimi S., Pulgarin C., Leterrier Y., RSC Adv., 5, 105416-105421 (2015).

Research Lab: prof. Yves Leterrier, Laboratoire de Technologie des Composites et Polymères