Title: Potential of the vitrimers as sustainable materials

Speaker： Mikihiro Hayashi (Nagoya Institute of Technology, Japan)

Time：October 14, 2022（10:00 am） 

Zoom ： 839 3114 4370

Abstract:

Usually, polymeric cross-linked materials, so-called thermosets, have been suffered from the lack of recyclability due to the formation of covalent bonded cross-links with permanent life time. This defect is very negative, considering the current international trend to seek realization of sustainable societies. To overcome this issue, incorporation of dynamic covalent bonds into network structures is admitted as a useful option, which provides sustainable functions, such as recyclability and healability, with cross-linked materials. Recently, a new type of dynamic covalent bonds has been developed, in which the associative bond exchange without distinct steps of bond dissociation and reassociation are operated (Fig. 1). Such materials have been termed vitrimers since the pioneering work reported by L. Leibler’s group (Science, 334, 965-968 (2011)). In vitrimer network, the dissociation of original bonds occurs exactly after the formation of new bonds, like in the case of SN2-type reaction. At above a certain activation temperature of the bond-exchange, the network starts to be rearranged with keeping the constant cross-link density.  Owing to these unique features of the bond exchange manner, vitrimers can be reprocessed without showing sudden flow at high temperatures, where the temperature dependence of viscosity is much weaker than the thermoplastics and follows Arrhenius-type relationship as shown in the inorganic silica glasses. Except the reprocessability, vitrimers can exhibit various useful functions, such as recyclability, healability.In the presentation, I will demonstrate some unique physics of vitrimers and a route for practical application on the basis of our original studies.

Brief Biography：

Mikihiro Hayashi received his Ph.D. degree from Nagoya University (Prof. Yushu Matsushita group) in 2015. During his doctor course, he had been selected as a JSPS research fellow (DC2) and experienced researches in ESPCI Paris-Tech (Prof. Ludwik Leibler) and in  Shanghai Jiao Tong University (Prof. Xinyuan Zhu). He then re-joined Ludwik Leibler’s group as a postdoc, and experienced another postdoc in Prof. Masatoshi Tokita in Tokyo institute of technology. In 2017, he became an assistant professor in Prof. Akinori Takasu group (Nagoya institute of technology), and currently manages his own laboratory as a PI. His research interest is the design of functional cross-linked materials