Nanostructures Based on Self-Assembly of Block Copolymers

Block copolymers have attracted increasing interest for the synthesis of nanomaterials and fabrication of nanostructures due to their ability to self-organize at nanometer scales. A variety of nanoscale morphologies can be obtained by controlling the comp

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Nanostructures Based on Self-Assembly of Block Copolymers E. Bhoje Gowd, Mallikarjuna Shroff Rama, and Manfred Stamm

Abstract

Block copolymers have attracted increasing interest for the synthesis of nanomaterials and fabrication of nanostructures due to their ability to selforganize at nanometer scales. A variety of nanoscale morphologies can be obtained by controlling the composition and architecture of the individual block components. In this chapter, we highlight the recent advances in the formation of nanostructures in bulk, generation of block copolymer based nanotemplate ordered thin films and their potential applications in nanofabrication including template nanolithography, deposition of functional nanomaterials as well as nanoporous membranes.

8.1

Introduction

Nanometer scale patterning of surfaces has attracted great attention due to recent applications in interdisciplinary areas including electron beam lithography, x-ray lithography, optical lithography, and imprint lithography [1–8]. However, a feature size less than 30 nm in a large area is hard to achieve with the above-mentioned lithography techniques. Block-copolymer based nanofabrication is an emerging approach for the production of nanostructured materials due to the unrelenting reduction in feature sizes on integrated circuitry [9–15]. Block copolymers are a class of macromolecules that are produced by covalent connection of two or more

E.B. Gowd (*) Materials and Minerals Division, National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum, India e-mail: [email protected] M.S. Rama • M. Stamm Department of Nanostructured Materials, Leibniz Institute of Polymer Research Dresden, Dresden, Germany M. Stepanova and S. Dew (eds.), Nanofabrication, DOI 10.1007/978-3-7091-0424-8_8, # Springer-Verlag/Wien 2012

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chemically dissimilar homopolymers. The number, composition and connectivity of blocks determine the molecular architecture of block copolymers (e.g. diblock, triblock, multiblock, and star or graft copolymers). Complex architectures have been generated. Since blocks are usually not compatible depending on molecular weight and effective monomer interaction, block copolymers can self-assemble to form a variety of nanoscale periodic patterns including spheres, cylinders, and lamellae with typical dimensions of 5–50 nm [12–23]. In many of the applications block copolymers are used in the form of thin films. The optimal utilization of these phase-separated block copolymer thin films involves several steps, i.e. working with appropriate film thickness, controlling orientation and lateral ordering of the microdomains, and generation of ordered arrays of nanopores [17–19, 21]. Thus obtained block copolymer templates have been used in various nanofabrication processes to generate patterns of interest by further treatment with a variety of different methods including chemical and physical vapor deposition, electrodeposition, incorporation of metal nanoparticles, and chemical reduction tec

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