The use of biomass-derived plastics is a major challenge in the global goal of saving the planet from pollution. However, the use of most biomass-derived plastics is limited due to their poor thermal stability. Joint research between JAIST and U-Tokyo University has successfully developed white biotechnological conversion of cellulosic biomass to aromatic polymers. They have the highest thermal degradation of all plastics ever reported. The new material is detailed in an article for Advanced Sustainable Systems magazine.
The development of new energy-efficient materials using biomass is an important part of creating a sustainable environment. However, currently available bioplastics are mostly aliphatic. They thus have poor thermal stability, which severely limits their use. Finally, unfortunately, plastic is so popular precisely because of its versatility. It is important that it can withstand certain temperatures (remember the plastic food containers, in which it is possible, although not very useful, to heat food). Aromatic backbone polymers are widely known for their high thermal stability. However, the production of aromatic heterocyclic monomers from biomass is almost impossible due to the complexity of controlling their structure.
Two specific aromatic molecules, 3-amino-4-hydroxybenzoic acid (AHBA) and 4-aminobenzoic acid (ABA), were obtained from kraft cellulose (inedible raw materials) by Professor Onishi and his research group in Tokyo. Recombinant microorganisms selectively increased the productivity of aromatic monomers and inhibited the formation of by-products. Professor Kaneko and his research team at JAIST have chemically converted AHBA to 3,4-diaminobenzoic acid (DABA). Subsequently, it was polymerized to poly (2,5-benzimidazole) – ABPBI – by polycondensation and processed into a heat-resistant film. In addition, the introduction of a very small amount of ABA with DABA dramatically increased the heat resistance of the resulting copolymer and the processed film.
An organic plastic with excellent thermal stability (over 740°C) has been developed from inedible biomass raw materials without the use of heavy inorganic fillers. This innovative molecular design of ultra-high temperature polymers, by controlling π-conjugation (or bond conjugation), can help eliminate harmful plastics that pollute the environment.