Abstract: A modified approach to prepare novel amphipathic octadecyl-quaternized carboxymethyl chitosan (QACMC) was reported, in which carboxymethyl chitosan (CMC), prepared fromchitosan, was made to react with glycidyl octadecyl dimethylammonium chloride; thus, the octadecyl quaternary ammonium group was introduced into CMC. The structure and thermal properties of these derivatives were characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H-NMR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The crystalline properties of QACMC were perfect, and it had a high degree of crystallinity. All the chitosan derivatives had good thermal stability when the temperature was lower than 200 ℃. The moisture-absorption and retention abilities of QACMC were lower than that of hyaluronic acid (HA) and CMC. The carboxymethyl and quaternary ammonium groups did not show a synergistic effect, and the effects of both the molar mass and the hydrophobic side chains of long alkyl moieties were important. Minocycline hydrochloride was successfully incorporatedintoQACMCpolymeric micelles with a remarkably highe fficiency (10.9%,mass fraction). QACMCpromises to be a high-potential delivery vector for lipophilic drugs.

Key words: Quaternized carboxymethyl chitosan, Crystallinity, Moisture absorption, Moisture retention, Drug loading capacity