Enzymatic polymer synthesis for materials and environmental applications
Description
This dissertation is based on research directed towards the understanding of enzymatic polymerization in microstructured media, and the development of relevant applications. Specifically, the enzyme horseradish peroxidase is used to couple phenols and aromatic amines to the corresponding polymers. This is a reaction that has a biological analog in the synthesis of lignin. The approach followed is to use simple substrates to produce useful polymers that are conjugated and have applications to nonlinear optics. The novelty of the research is that the synthesis is conducted in the microstructured environment of reversed micelles. It is shown that this environment is particularly suitable for the specific reaction as it allows maintenance of enzyme activity and additionally, allows monomer partitioning to the oil-water interface Several aspects of such polymer synthesis and related problems have been considered. First, surfactant-monomer(phenol) interactions in dry micelles are shown to lead to a phase transition from a low viscosity solution to an organogel. It is shown that hydrogen bonding plays a significant role in this phase transition. In water-containing micelles, polymer synthesis leads to polymer microspheres whose internal density can be controlled. These microspheres encapsulate enzymes, and it is shown that specific enzymes retain catalytic activity in these microspheres. Finally, the enzymatic synthesis of polyaniline is reported The dissertation also addresses an environmental problem related to the removal of aromatics from aqueous systems. A new process concept is developed here, wherein aromatics are first hydroxylated to the corresponding phenol through a well-studied chemical reaction, the Fenton reaction. Subsequently, the phenols are polymerized to insoluble oligomers using the enzymatic route. This two step route to remediation, it is proposed, results in the conversion of waste materials to useful products