Effects of Hydrophobic Modification of Chitosan on Transport Properties, Ion Exchange Capacities, and Enzyme Immobilization

摘要

Chitosan is a linear polysaccharide that is formed from chitin , which is abundant in the outer shells of insects and crustaceans. Chitosan is an inexpensive biopolymer, because it is the second most abundant biomass. It is also well known for it biocompatibility, biodegradability, chemical inertness, high mechanical strength, and non-toxic properties. It has been proposed by Buhler and coworkers that by hydrophobically modifying the chitosan backbone with a long alkyl chain, the polymer will form micelles . Previous research shows that the immobilization of enzymes within a micellar polymer such as hydrophobically modified Nafion? improves enzyme activity and increases its active lifetime . Nafion? is a perfluorinated sulfonate ionomer which can be modified with quaternary ammonium bromide salts of varying sizes . With increasing salt size, the micellar pore size increases and ion exchange capacity decreases . Because of its ability to immobilize enzymes, hydrophobically modified Nafion? has been proposed as a suitable component of a membrane based biofuel cell . Nafion? however is expensive and not biodegradable. This research examines the effect of hydrophobic modification of chitosan on its morphology, ion exchange capacity, transport properties of redox species. This research also studies enzyme immobilization within the membrane to determine its capability of replacing Nafion? in the fabrication of a biofuel cell.