Kei Saito1
Kyoto University1
Traditionally, polymers have been designed to possess irreversible covalent bonds between the repeating monomer units. However more recently, significant interest has been directed toward the synthesis of dynamic polymers that are held together by dynamic (reversible) covalent or non-covalent bonds which can reuse and recycle. Within their structures dynamic polymers contain a reversible bond that can be formed from the monomer units and cleaved back to the monomer units by heat or light. 2π+2πcycloaddition reactions are the dynamic reactions which can be formed and cleaved. A select few molecules are known to possess the ability to undergo this type of reaction such as cinnamine, stilbene, thymine, coumarin and styrylpyrene. The first part of this study focused on the full validation of the potential of these unique reversible reactions, topochemically controlled monomer to polymer transformation techniques using 2π+2π cycloaddition reactions are study to create new materials – such as photo-degradable and photo-reusable polymers and self-healing polymers.<br/>Lignin is the second most abundant biopolymer just after cellulose. Its structure is a complex 3D network of phenol compounds liked by C-C (carbon-carbon) or C-O-C (carbon-oxygen-carbon) bonds, thus representing a promising source of aromatic compounds. The second part of this study focused on the depolymerisation of lignin using the several mechanisms such as a redistribution. We also have developed the novel oxidative degradation of lignin using MnO<sub>2</sub> with blue-light with a formate ionic liquid to produces ethyl acetate and also water soluble depolymerised lignin products. The β-O-4 bonds in lignin were oxidised, which were then depolymerised by a green and recyclable ionic liquid, 2-hydroxy ethylammonium formate, under mild conditions.