[3Mp] Freshness keeping, Material cycles, Other food engineerings

[3Mp-09] Influence of layer-by-layer assembly methods on Turing pattern of chitosan–gelatin composite films

*Ryuichiro Ito¹, Fakfan Luangapai^3,4, Masanari Usami¹, Sota Hori¹, Nakako Katsuno², Iwamoto Satoshi^2,3 (1. Graduate School of Natural Science and Technology, 2. Faculty of Applied Biological Sciences, 3. Division of Science of Biological Resources, United Graduate School of Agricultural Science, Gifu University, 4. Department of Food Technology, Faculty of Science, Chulalongkorn University)

Keywords:Turing pattern, Layer-by-layer assembly method, film, SAXS, Chitosan

Chitosan, a natural polymer that forms thin films, has biocompatibility. However, the thermal resistance and strength of monolayer films are relatively low. To enhance the efficacy of chitosan films, we have been alternately layering chitosan with gelatin ¹⁾ and have confirmed that a stripe pattern in multilayer films with three or more layers. To understand how this pattern affects the properties of the film, we firstly examined the conditions under which the pattern is generated and observed the pattern.Acid-treated gelatin, alkali-treated gelatin, and chitosan were used to prepare the films. After preparing solutions of 7.5% for gelatin and 2.0% for chitosan, appropriate amounts of glycerin were added to each. These solutions were spread on a Petri dish and dried at 37℃. Three-layer films were prepared by LbL assembly method. The samples were stored at room temperature. Patterns were obtained for almost all of the six combinations of chitosan and gelatin films. The pattern variety was depending on the combination of the layers, and a geometric pattern was obtained. From the literature survey, it was found that the stripe pattern is a reaction-diffusion equation, i.e., a Turing pattern that occurs when two opposing reactions control each other. We performed a simulation in Python based on the Gray-Scott model and obtained simulation results that were almost consistent with the film pattern. In the future, we plan to measure the thermophysical properties using a differential scanning calorimeter to confirm the change in glass transition temperature caused by the pattern and to analyze the film structure using small-angle X-ray scattering to investigate the microstructure that is the origin of the pattern.