Starch functionalization: Epoxidation and Methacrylation reactions

Polymeric materials have been widely produced in the world industry in the last decades. These materials present various interesting properties such as high mechanical strength compared to their low density, toughness, corrosion resistance, electrical and thermal insulation and they are generally low cost. However, synthetic polymers cannot be included in the recycling system causing environmental problems. Functionalized biopolymers constitute a green alternative to the use of polymer derived from fossil fuel resources. The most used sub-class of biopolymers are polysaccharides like starch, cellulose and chitosan. Polysaccharides are biodegradable, low cost and abundant. In this project two different starch functionalization reactions were conducted: epoxidation and methacrylation. The goal was to obtain functionalized starch derivatives curable under UV light. Various epoxidation reactions were carried out using epichlorohydrin (ECH) as reagent in a sodium hydroxide (NaOH) solution under nitrogen atmosphere. The NaOH was used as nucleophilic catalyst. Different conditions and stochiometric ratios were varied and the progress of the reaction was carefully monitored. Methacrylation reaction was carried out in dimethyl sulfoxide (DMSO) with methacrylic anhydride (MA) as reagent and triethylamine (TEA) as nucleophilic catalyst at room temperature. Both funcionalizations were conducted in stirring conditions and the final products were purified with three precipitation in ethanol. In order to fully characterize the starting polymer, native maize starch was analysed with different techniques such as Fourier Transform Infrared Spectroscopy (ATR-FTIR), Proton Nuclear Magnetic Resonance (1H-NMR), Carbon-13 Nuclear Magnetic Resonance (13C-NMR) and Thermogravimetric Analysis (TGA), The success of both the epoxidized and methacrylated reactions was confirmed by ATR-FTIR, 1H-NMR and 13C-NMR analysis. The functionalization reactions lead to interesting results which suggest further investigations.