Supramolecular nanostructures of luminescent organoboron polymers
Creators: name: Cheng, Fei
Publisher: name: No Publisher Supplied
Year: 2013

description: Over the past several decades, organoboron compounds have been widely studied with respect to applications as reagents in organic synthesis, Lewis acid catalysts, luminescent materials, chemical sensors, ceramic precursors and nuclear detectors. Besides the basic physical and chemical properties, materials for most practical applications require favorable processing characteristics. Polymeric materials are advantageous in this respect and especially, self-assembled functional polymeric nanostructures are promising for the development of new optical, electronic, biological and energy-related materials. Therefore, research on the synthesis and properties of well-defined boron-containing polymers is an emerging area that has drawn great interest of chemists and material scientists.    This dissertation describes a “molecule-polymer-material” bottom-up methodology for the fabrication of nanostructured materials based on luminescent organoboron polymers. A series of novel organoboron monomers with tunable photophysical properties and excellent stability were developed via efficient organic and organometallic reactions. Using reversible addition-fragmentation chain transfer (RAFT) polymerization, well-defined luminescent organoboron homopolymers and block copolymers with controlled molecular weight and narrow molecular weight distribution were successfully synthesized. Core-crosslinked star polymers with a luminescent boron quinolate core were also achieved by “arm-first” RAFT polymerization of a difunctional boron quinolate crosslinker.     These block copolymers and star polymers serve as versatile building blocks for nanostructure fabrication. In selective solvents, the block copolymers and star polymers form self-assembled nanostructures, such as micelles, vesicles, large spherical and spindle-shaped aggregates. By introducing pyridine-functionality onto the block copolymer structure, luminescent polymeric Lewis bases were synthesized and utilized for the preparation of polymer/inorganic co-assembled nanostructures. The borinic acid functionalized block copolymers act as effective H-bonding donors that form supramolecular co-assemblies with poly(4-vinylpyridine) (H-bonding acceptor). Triarylborane compounds and polymers have been utilized as chemical sensors for toxic anions, such as fluoride and cyanide. Through rational polymer architecture design, we synthesized a series of dimesitylphenylborane-functionalized polymers, including homopolymer, block copolymer and block-random copolymers, for F- binding studies.  For the first time, (1) we elucidate the chain-architecture effect on F- binding and observed amplified fluorescence quenching for the homopolymer structure; (2) a dual responsive chemical sensor for F- was developed based on the block copolymer micelles in DMF, that F- binding leads to the fluorescence quenching and the dissociation of block micelles; (3) the positively charged block-random copolymer was found to be an effective F- sensor in polar solvents, such as DMF and DMF/water mixture, due to the electrostatic interaction.