Structure-function relationship in novel polyphenolics
Description
The synthesis, properties and applications of hydroxyaromatic polymers, synthesized enzymatically in AOT/Water/Isooctane water-in-oil microemulsion is the subject of this dissertation The enzymatic polymerization in such microstructured media furnishes the final polymer product with the unusual morphology of interconnected microspheres. Fundamental characterization of the nature of interaction of a model polymer, poly(4-ethylphenol), with the surfactant AOT, as well as various solvents was carried out to elucidate the molecular mechanism of the morphology development. From an applied perspective, presynthesized poly(4-ethylphenol) was precipitated using AOT/Water/Isooctane water-in-oil microemulsion as the non-solvent to give spherical microparticles. Of specific interest was the encapsulation of macromolecules and nanoparticles initially solubilized in the water droplets by the precipitating polymer matrix. This technique was utilized to synthesize catalytically active and superparamagnetic microspheres, containing entrapped enzyme and nanoparticulate ferrites, respectively The enzymatically synthesized polymers possess a fully aromatic backbone and hence are expected to have unique pi conjugated structure. On the basis of this hypothesis several conjugated luminescent polymers were synthesized using 2-naphthol and 2,6-dihydroxynaphthalene as the starting monomer. Chemical tuning of the emission properties of these polymers were achieved by copolymerization with 4-ethylphenol which is not a luminescent molecule. Addition of 2,6-dihydroxynaphthalene in dry reversed micellar solutions of AOT induced a dramatic phase transition to a clear luminescent organogel. Hydrogen bonding interaction between the hydroxyl groups and the head group of AOT form the basis of such gels. The microstructure of the gel was probed using NMR and FTIR spectroscopy Finally, thiol group containing polymers were synthesized to bind nanoparticulate CdS, forming novel photoresponsive polymer-semiconductor nanocomposites. The resulting composite material was characterized for its photoluminescence properties. The composite is soluble in a range of organic solvents and shows no signs of agglomerative destabilization over time