Aggregation behavior of N-carboxyethylchitosan in aqueous solution: effects of pH, polymer concentration, and presence of a gemini surfactant |
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Authors: | Baoliang Peng Changjun Peng Honglai Liu |
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Institution: | Key Laboratory for Advanced Materials and Department of Chemistry, East China University of Science and Technology, Shanghai 200237, China |
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Abstract: | A kind of biocompatible derivative of chitosan, N-carboxyethylchitosan (CECh) with a degree of substitution of 0.21 (DS 0.21) was synthesized by a Michael addition reaction. The aggregation behavior of CECh in aqueous solution under the effects of pH, polymer concentration, as well as a gemini surfactant, was investigated by turbidity, zeta potential, fluorescence spectroscopy, viscosity, and surface tension measurements. In the pH range of 3-11, the macroscopic phase separation of CECh from water occurs near the isoelectric point (IEP) due to the intense electrostatic attraction, and the intermolecular interaction at pH 4 is stronger than that at pH 10 over the whole CECh concentration region. The critical aggregation concentration (CAC) of CECh/12-n-12 (n = 3, 6) in basic media is determined to be between 0.0010 and 0.0015 mmol/L, and the length of the surfactant spacer is found to play an important role in the interaction of 12-n-12 with CECh. |
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Keywords: | N-Carboxyethylchitosan Aggregation behavior Gemini surfactant |
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