Research groups at the University of Tokyo, Tokyo University of Agriculture and Technology, and Kyoto University have succeeded in developing a resin that is environmentally friendly and has excellent heat resistance from the enzyme of worm tooth fungus, and published the research results in "Scientific Reports".
Currently, there is a strong demand for the development of "bio-based plastics" made from renewable plant biomass.Conventional bio-based plastic synthesis methods using naturally occurring high molecular weight polysaccharides break the original bonds and structures, and do not take advantage of the characteristics of biomass.In addition, high molecular weight polysaccharides such as starch and cellulose have a problem that they do not have the "thermoplasticity" essential for plastics.
The research group focused on the fact that plaque (biofilm) produced by worm tooth fungi is a polysaccharide, and using this enzyme, a high molecular weight polysaccharide "α-1,3-" that has a binding mode that is neither cellulose nor starch. Succeeded in synthesizing "glucan".It is an environmentally friendly synthetic method because it is insoluble in water and can be easily recovered.
From this, it was also clarified that the "α-1,3-glucan ester derivative" in which the three hydroxyl groups in the molecular structure of α-3-glucan are replaced with ester groups has high heat resistance.Its melting point is about 1,3 to 300 ° C, which exceeds 340 ° C of polyethylene, which is a typical petroleum synthetic plastic, and 120 ° C of polyethylene terephthalate.
It was also discovered that α-1,3-glucan itself does not have thermoplasticity, but that it exhibits high thermoplasticity when it becomes an α-1,3-glucan ester derivative.The breaking strength of the film molded with this derivative exceeds 40 MPa, and it is expected to be used as an engineering plastic due to its high heat resistance and mechanical properties.Furthermore, since α-1,3-glucan is a biofilm originally synthesized in the oral cavity, it may be used as an orally available material / medical material.
In this study, we have also succeeded in biosynthesizing a huge polymer exceeding 15 by lowering the reaction temperature to 70 ° C when synthesizing in vitro.In the future, along with establishing a mass synthesis method for polymers, we plan to develop injection-molded products with high strength and high heat resistance using derivatives.
