Chitosan with a low viscosity (MW 371000 determined by high-performance liquid chromatography, DD=85 determined by FT-IR) was purchased from Fluka (Tokyo, Japan). Methanesulfonic acid and phosphorus ...
Resorcinol, 4-nitrobenzonitrile, methanesulfonic acid, thionyl chloride and triethylamine were purchased from TCI (Tokyo Chemical Industry Co., Ltd., Tokyo, Japan). Microcrystalline cellulose was ...