Date of Award

1-1-2011

Document Type

Campus Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

Chemistry

First Advisor

Brian C Benicewicz

Abstract

This research focuses on using controlled polymerization techniques such as Radical Addition Fragmentation Chain Transfer Polymerization (RAFT) to graft polymers from the surface of colloidal silica nanoparticles for incorporation in polymers to make composites.

In the first part of this work, a new strategy based on Marcomolecular Design via Interchange of Xanthates (MADIX) polymerization was demonstrated to graft polymer brushes on silica nanoparticles. For this work, a xanthate was anchored on the surface of silica nanoparticles using click chemistry. Polymerizations of styrene and vinyl acetate were conducted from the surface of xanthate anchored silica nanoparticles The second part of this work is focused on preparing binary brush grafted silica nanoparticles. Two robust techniques utilizing RAFT polymerization to synthesize binary polymer brush anchored nanoparticles have been demonstrated. In the first technique, step-by-step RAFT polymerization was used to prepare binary brush grafted nanoparticles. In a second approach to prepare binary brush grafted nanoparticles a combination of RAFT and ATRP polymerization was utilized This versatile route of using step-by-step controlled polymerization techniques enables us to control individual molecular variables such as composition, molecular weight, molecular weight distribution and grafting density of the individual populations on the surface of nanoparticles.

The last part of this work describes the synthesis of benzimidazole side chain containing monomers and polymers. A new monomer 2-(4-vinylphenyl)-1H-benzo[d]imidazole containing a radically polymerizable group was synthesized and progress was made towards understanding its polymerization. RAFT polymerization was used to control the polymerization of 5-(1H-benzimidazol-2-yl)-propan-1-methacrylate monomer and kinetics of polymerization was investigated. In a third approach to prepare benzimidazole functional polymers and nanoparticles, a combination of RAFT polymerization and click chemistry was used to graft polyAHMA from the surface of silica nanoparticles. Subsequently 4-ethynylbenzaldehyde was clicked onto the grafted polymer chains using copper mediated alkyne/azide click reaction.

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