Synthesis and characterization of N-diethyl methyl chitosan

Biodegradable polymers such as chitosan have been used extensively in biomedical fields in the form of sutures; wound dressing and as artificial skin. Colonic drug delivery for either local or systemic effects has been the subject of much research over the last decade. Chitosan exhibits poor solubility at pH values above 6 that prevent enhancing effects at sites of absorption of drugs. In the present work, N-diethyl methyl chitosan (DEMC) was prepared based on a modified two-step process via a 2(2) factorial design to optimize the preparative conditions. DEMC Polymer with different degrees of quaternization for pharmacological and pharmaceutical experiments was achieved. The reaction was optimized using different amounts of reactants. pH-metric titration and infrared methods predetermined the degree of deacetylation of the starting chitosan. DEMC Chloride was characterized using FTIR and H-1 NMR spectroscopies. Based on NMR calculation, high degree of quaternization was achieved through the optimized two-step process. Under our optimized conditions, (i.e. the second step, chitosan 1.5%, ethyl iodide 30%, NaOH 3.1%, 60degreesC, 6h), the prepared DEMC comprised a degree of quaternization of 79%. The prepared N-diethyl methyl chitosan chlorides were rapidly and completely dissolved in water at room temperature.