Preparation and Characterization of pH-Responsive Lignin-based Colloidal Spheres
The quaternary ammonium of lignin(QAL) was synthesized by chemical conversion of alkali lignin(AL).The complex was formed based on electrostatic interactions by QAL with sodium dodecyl benzenesulfonate(SDBS) and the pH-response colloidal spheres were prepared with complex in ethanol-water solution via self-assembly.The structure and formation process of colloidal spheres were investigated by XPS, SEM, TEM, elemental analysis, and contact angle measurements.The results showed that pH-responsive colloidal spheres are obtained from gradual hydrophobic aggregation of QAL/SDBS complex molecules, and the colloidal spheres have hydrophobic cores and hydrophilic shells.At pH=3, the colloidal spheres are stable due to the hydrophobic and electrostatic interactions between QAL and SDBS.At pH=7.5, the carboxylic acid groups on the QAL become progressively ionized.In this case, the colloidal spheres start disaggregated due to electrostatic repulsion.At pH=10.5, the electrostatic repulsion between the QAL and SDBS molecule increases because of the ionization of carboxyl and phenolic hydroxyl groups on the QAL.Therefore, the colloid spheres disaggregation completely.The colloidalsphere are stable under the acidic condition and disaggregates under the neutral condition, so it has the potential for used in drug delivery systems.
Quaternary ammonium of ligninSodium dodecyl benzenesulfonateColloidal spherepH-Responsive
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