Fabrication and characterization of sharkskin mimicked chitosan-graphene oxide nanocomposite membranes

Abstract

In the presented thesis, fabrication and characterization of sharkskin mimicked polymeric membranes were investigated with the aim of achieving membranes with enhanced biological, physicochemical and mechanical properties namely biodegradability using Chitosan as the main polymer and Graphene Oxide(GO) as the additive. Sharkskin micro-patterns are known to have antibacterial e ects therefore possibility of replicating its surface topography with chitosan, was hypothesized and proved to be achievable. In order to replicate sharkskin surface structure, soft lithography method was chosen by using Polydimethylsiloxane (PDMS). Chitosan solution was prepared by dissolving puri ed pristine Chitosan in dilute acetic acid solution (2%v/v). For Chitosan/GO nanocomposites membranes, solutions of chitosan containing various amounts of GO (0.1%w/w, 0.2%w/w and 0.3%w/w) were prapared using solvent-casting method, Chitosan/GO solutions were cast upon sharkskin negative PDMS molds. Mechanical characterizations including Elongation at Break and Tensile Strength were done using Chitosan based plain membranes. Scanning Electron Microscopy(SEM) was conducted as morphological characterization along with Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Water Contact Angle and Swelling Ratio as chemical characterizations. According to the results, the hypothesis of possibility of mimicking the surface micro-pattern of sharkskin using biodegradable natural polymer was veri ed. Additionally, preparation of sharkskin mimicked chitosan/GO nanocomposite membranes proved to be possible with acceptable quality of replication. Furthermore, adding GO to chitosan, resulted in considerable improvements of chemical and mechanical properties of polymer.|Keywords : Chitosan, Graphene Oxide, Biomimic Structures, Soft Lithography, Solvent Casting, Composite.