SYNTHESIS OF POLYFERROCENYLSILANE BLOCK COPOLYMERS AND THEIR CRYSTALLIZATION-DRIVEN SELF-ASSEMBLY IN PROTIC SOLVENTS.
Author: Hang Zhou
Publisher:
Published: 2018
Total Pages:
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DOWNLOAD EBOOKPolyferrocenylsilane (PFS) di-block copolymers self-assemble in selective solvents to form rod-like micelles, driven be the crystallization of the PFS block in the core. One of the unique features of these rod-like micelles is that the length can be extended upon addition of an extra amount of PFS block copolymers in a good solvent for both blocks. This process, referred to as the living crystallization-driven self-assembly (CDSA), has been utilized to prepare near monodisperse rod-like micelles. To further investigate the potential bio-medication application of these rods, I set out to synthesize new PFS BCPs with water-soluble thermoresponsive corona to prepare uniform nano-rods in polar media, and study their solution behavior. The first part of my thesis describes the synthesis and living CDSA of poly(ferrocenyldimethylsilane-b-N-isopropyl acrylamide) (PFS-b-PNIPAM) by a Cu-catalyzed alkyne/azide coupling reaction to covalently combine the two homopolymers. In self-assembly studies, I found that the growth rate of the rod-like micelles in alcohol solvents decreased dramatically when the number of PNIPAM repeating units was increased. Varies attempts to transfer the micelles to water were accompanied by extensive fragmentation. I attributed the phenomenon to the cononsolvency of PNIPAM corona in alcohol/water mixture. The second part describes the preparation of a photocleavable PFS-hv-poly(2-vinylpyridine) (P2VP) block copolymer bearing an o-nitrobenzyl ester (ONB) group at the junction. I investigated in detail the UV light-induced cleavage of the P2VP corona chains from the rod-like micelles by GPC, TEM and multiangle light scattering. The third part in the thesis describes the formation of rod-like co-micelles with segregated coronas via living CDSA of two mixed unimers of PFS-b-PNIPAM and PFS-hv-P2VP. By controlling the epitaxial growth rate of the two competing species, the morphology of the co-micelles could be varied from patchy to block co-micelles. The fourth part describes the synthesis and living CDSA of PFS-b-poly(oligo(ethylene glycol) methyl ether methacrylate) (PFS-b-POEGMA). I explored the self-assembly condition of this polymer in different alcohol media and found a methanol/ethanol mixture as selective solvent to prepare uniform nano-rods by living CDSA. These nano-rods stayed intact after transfer to water. The thermoresponsiveness of these uniform cylindrical brushes was investigated by multiangle light scattering.