Satoshi Koizumi
Ibaraki University, Japan
Title: Reaction induced self-assemblyâ€, tracked by small-angle neutron scattering
Biography
Biography: Satoshi Koizumi
Abstract
When we observe structure formations that take place in the natural world, we notice that self-organization occurs continuously and immediately next to the synthesis reaction. An example is cellulose, which usually exhibits excellent crystallinity via intra- and intra-molecular hydrogen bonding due to its symmetrical molecule structure. It is therefore known to be generally insoluble in solvents such as water. However, this is not true for the microbial cellulose films (called pellicle) created by microorganisms (Acetobacter Xylimun). Pellicle has a high water content with water making up 99% of the total structure. In other words, it can be denoted that this microorganism has some means of preventing cellulose from crystallizing, keeping it amorphous, and storing a large amount of water in it. Pellicle is thus a supramolecular system assembled by a microorganism. This supramolecular formation process is a continuous self-organizing transition consisting of biosynthesis of cellulose followed by excretion of the cellulose from the bacterium, crystallization, and condensation. The biosynthesis triggers the interplay between the chemistry and physics of the product’s self-organization. To track it, we aimed to perform in-situ observation in the reaction solution by using small-angle neutron scattering (SANS). In this paper, we discuss living anionic polymerization, solid-phase radical polymerization by radiation processes, cellulose biosynthesis, and artificial synthesis of cellulose by enzymatic catalysis.