Scientists in Japan have invented a new method for producing polymers. This invention is anticipated to result in the creation of more ecologically friendly, heat-resistant, and transparent plastics.
Prior studies, like the one conducted by Nobel laureate Giulio Natta’s group in the 1960s, used a technique known as asymmetric cationic polymerization to create polymers. Their group, however, was unable to control the molecular weight.
Controlling the molecular weight of polymers, particularly those used in plastics engineering, is critical as it impacts many of the characteristics of plastics. High molecular weight polymers with a stiffer flow provide the best performance because they are harder and more resistant to chemical and environmental destruction.
A team led by Lecturer Mineto Uchiyama and Professor Masami Kamigaito of Nagoya University’s Graduate School of Engineering, and Professor Kotaro Sato of Tokyo Institute of Technology successfully synthesized optically active polymers with governed molecular weight. Researchers merged two existing methods to establish the asymmetric living cationic polymerization combination technique: their living cationic polymerization and Natta’s asymmetric cationic polymerization.
This new method produces polymers with controlled molecular weight and high optical activity that can be controlled chemically. Their research was published in the Journal of the American Chemical Society.
Monomers are the building blocks of polymers and can be obtained from a variety of sources. To put their new method to the test, the researchers began with benzofuran, a natural resource that is a precursor to the polymer polybenzofuran. Benzofuran is capable of forming rigid polymers with a high glass transition temperature and high transparency.
It is also chemically recyclable. Due to its greater glass transition temperature, the polymer retains its hard shape even at high temperatures. As a result, benzofuran is useful in the production of long-lasting transparent thermoplastics.
Our novel polymerization method could control both the chirality and the molecular weight of polybenzofuran, leading to unique optically active polymer materials with highly controlled structures.
Mineto Uchiyama, Lecturer, Graduate School of Engineering, Nagoya University
“This research is expected to lead not only to the development of new precision polymerization reactions but also to the development of new functional polymer materials. Since polybenzofuran has the properties of a highly heat resistant plastic, it is expected to become a new material as a heat resistant resin with optical activity.”
Moreover, Uchiyama sees a wide range of applications for the compound.
“Polybenzofuran has a structure similar to polystyrene, which is one of the main plastics used daily for various products, such as plastic containers, cases, and packaging,” he says.
Uchiyama further adds, “While polybenzofuran is not used as a commercially available plastic, it has a stiffer molecular structure and a higher glass transition temperature than polystyrene. We see it being used as a new plastic with good thermal properties. Furthermore, its unique optical properties could give additional functionalities.”
The research was funded by the Japan Society for the Promotion of Science and the Asahi Glass Foundation through a Grant-in-Aid for Scientific Research on Science and Technology.
Uchiyama, M., et al. (2022) Asymmetric Cationic Polymerization of Benzofuran through a Reversible Chain-Transfer Mechanism: Optically Active Polybenzofuran with Controlled Molecular Weights. Journal of the American Chemical Society. doi.org/10.1021/jacs.2c02569.