Abstract
A simple method to prepare hollow microbeads composed of hydroxypropyl chitosan (HPCH) using W/O emulsion method was described. For this purpose, HPCH was synthesized by chitosan and propylene oxide under alkaline catalyst. FT-IR and solid state CP/MAS 13 C-NMR confirmed the incorporation of hydroxypropyl moieties on chitosan. The degree of substitution(DS) of HPCH was around 3.5 as detected by elemental analysis. Wide angle X-ray diffraction (WAXD) pattern of HPCH showed lower crystallinity than that of chitosan. The physical properties such as solubility, hydrophilic character, and thermal stability of the HPCH were significantly changed as compared with those of chitosan. HPCH had improved solubilities in several organic solvents, compared with chitosan. After cross-linking IIPCI-I with epichlorohydrin in water-in-oil (W/O) emulsion system, microbeads were obtained. Scanning electron microscope picture reveals that they are hollow microbeads which have an asymmetric shell structure with nonporous inner skin layer and porous outer surface layer. The mean diameter of the hollow microbeads was 180 μm with shell thickness of 1.5 μm.
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