Chitosan-based Materials: Synthesis, Properties & Tunability

Abstract

This Thesis aims to extend the knowledge on the effective utilization of chitosan for potential industrial applications and to show its path towards functional materials. One of these applications is an effective, highly porous, biobased support, which can efficiently hold active phases such as metal organic frameworks (MOFs) and zeolites in its structure. We discovered a new synthesis route for these highly porous chitosan structures and investigated different ways to incorporate MOFs while keeping them active for CO2 conversion. Another potential application is to synthesize chitosan-based film materials, whose properties can be widely tuned with biobased green additives. Hence, we investigated a set of seven biobased additives which can vary the film’s properties from soft to stiff, and from clear to opaque, in their uptake behaviour into the chitosan matrix. Further we analysed the film properties of the final material in its fresh state, as well as followed them over the period of 400 days in order to investigate their long-term stability and early signs of decay such as yellowing and enhanced brittleness. We further also investigated the possibilities to vary the properties of chitosan on its own by depolymerization of the polymer with a set of heterogeneous supported bimetallic nanoparticles. With these catalysts, we were able to roughly half the initial polymer chain length. We propose a rough depolymerization mechanism on the catalyst surface and propose the role of the individual catalyst components. Finally, we show the huge potential of chitosan in future industrial applications and potential future projects.