"DuPont des Matériaux" Award 2007 - KRISHNAMOORTHY Sivashankar

"For outstanding results on functional material nanopatterning, his creativity and his team spirit which contributed to a successful CSEM-EPFL collaboration"

Self-assembly of tunable, responsive polymer nanostructures : tools for nanafabrication of functional interfaces.

Fabrication of structures with nanometer scale dimensions are highly sought after for enabling device miniaturization, in addition to drawing benefits from the novel properties and capabilities that arise in the nanoscale. Surface supported nanostructures are particularly relevant for several applications like optical, electronic, sensor and other functional devices. Deriving benefit out of nanostructures demand one or more of the following attributes: 1) nanostructures spanning large areas of surface with excellent homoegenity and integrity 2) use of manufacturing compatible processes, 3) maintaining cost and time economy, 4) precise placement of nanostructures onto addressable micron scale areas on surface. The work presented in this thesis demonstrates a technology platform based on self-organization of diblock copolymer micelles on surfaces addressing the above mentioned demands, to create high density two dimensional arrays of a variety of nanostructures with fine-tunable dimensions, spacing, surface coverage and control over surface placement. Polystyrene-block-poly(2-vinyl pyridine), polystyrene-block-polyacrylic acid were chosen as model systems to demonstrate the utility of this self-assembly approach towards achieving other functional nanostructures such as metal/metal oxide/semiconductor nanoparticle arrays and nanoscale pillar and hole arrays on Si, Si3N4, SiO2 and Quartz substrates. Preliminary results demonstrating the application of these nanostructured surfaces in areas such as carbon nanotube growth, controlling human stem-cell adhesion and expression, super-hydrophobic surfaces and responsive surfaces are presented. Some of these applications formed basis of successful industrial projects. The strategies employed are general and hence can be applied to a broad class of copolymer molecules.