Chemical and Biomolecular Engineering - Theses

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Directed self-assembly of block copolymers and nanostructures

Chen, Chao ( 2017)

Self-assembly of block copolymers (BCPs) has attracted considerable attention for decades due to its potential in novel applications. The key to achieve their function critically relies on the control of nanostructure, shape and morphology of the BCP assemblies. The aim of this thesis is to develop a toolbox to manipulate the nanostructure of BCPs in a reliable and predictable manner, and provide mechanistic insights into their self-assembly behaviour. In this work, the strategies used to control the shape and morphology of BCP assemblies lie in three areas: (a) copolymer composition; (b) control of molecular weight distribution; and (c) interfacial properties. In this thesis, a series of BCPs have been synthesised at different compositions and their self-assembled structures have been reported. The influence of the skewed molecular weight distribution and varied dispersity on BCP self-assembly was explored in both solution and thin film systems. The interface between BCP nanoparticles and the surrounding medium was investigated and a morphological evolution from onion-like spheres to axially stacked lamellae has been observed. It is envisaged that the modification of copolymer chemistry and a combination of these addressed strategies will facilitate the synthesis of BCPs assemblies with higher structural complexity.