Towards functional nanostructures by crystallisation-driven self-assembly

• Main Author: Lunn, David John
• Published: University of Bristol 2014
• Subjects: 547
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653077

This Thesis describes the synthesis, functionalisation and self-assembly of a series of PFS-b-polyvinylsiloxane copolymers (PFS = polyferrocenylsilane). This simple crystalline-coil block copolymer (BCP), containing a PFS block suitable for crystallisation-driven self-assembly (CDSA) and a siloxane block suitable for the introduction of molecular complexity, is an ideal starting point for the bottom-up preparation of functional nanostructures. Chapter 2 outlines enabling chemistry that provides a platform for the majority of the work in this Thesis. It describes the preparation of PFS-b-polyvinylsiloxane copolymers and their subsequent functionalisation to tune the properties of the resulting materials or incorporate more complex functionality for subsequent applications. Chapter 3 describes the CDSA of brush BCPs prepared by the thiol-ene functionalisation of poly( ferrocenyldimethylsilane )-b-poly(methylviny lsiloxane) (PFDMS-b-PMVS) with n-alkane thiols. The rate of CDSA is influenced by the cocrystallisation of brush and linear BCPs and can be manipulated to afford micelles with nanosegregated coronas by gradient CDSA, an analogous process to a covalent gradient copolymerisation. Chapter 4 describes the immobilisation of red, green and blue emitting fluorophores on PFDMS-b-polysiloxane copolymers. By the sequential CDSA of fluorescent BCPs, or mixtures thereof, multicompartment micelles are prepared in which the emission of each segment is precisely controlled to produce colours throughout the visible spectrum and prepare structures analogous to nanoscale pixels and barcodes. Chapter 5 describes the radical hydrophosphination and CDSA of PFDMS-b-PMVS to afford monodisperse cylindrical micelles. On addition of a Pd precursor, · intermicelle crosslinking occurs affording tunable Pd-coated fibres that remain active to further CDSA. FUl1hermore, chains and networks can be prepared by the coordination-driven self-assembly of multicompartment micelle building blocks. Chapter 6 describes future directions and preliminary results for the use of crystalline-coil BCPs, where creativity and control at the small molecule scale is desirable for the transfer of complexity through hierarchical self-assembly processes for the optimisation of end nanostructure function.