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摘要
Monoquaternary cationic polymerizable surfactants of type N-acryloyl-N'-methyl-N'-alkyl piperazinium bromide based on piperazine heterocycle was synthesized by reacting N-acryloyl-N'-methyl piperazine with the corresponding n-alkyl bromide (decyl, dodecyl, tetradecyl, and hexadecyl) in anhydrous acetone at room temperature. The resulting surfactants were deliquescent to display any sharp melting points. The surface activity was studied by surface tension measurements. Due to the complex head group geometry of these surfactants, the critical micelle concentration value was high in comparison to the analogous alkyltrimethyl ammonium bromides of similar alkyl chain length. The surfactants were polymerized by micellar (in water) and isotropic (in benzene) conditions and the resulting polymers were characterized by solubility and viscosity studies. The polymers prepared in water showed higher viscosity than the ones prepared in benzene as a result of micellar aggregation in water. The reduced viscosity of the polymers in polar solvents such as methanol and dimethyl formamide (DMF) showed polyelectrolyte-like behavior, whereas nonelectrolyte behavior was observed in chloroform. pH-responsive hydrogels were prepared by polymerizing the surfactants in the bicontinuous phase of a microemulsion. The resulting polymers did not exhibit any definite micro/nanostructure due to cross-polymerization of the hydrophilic oil in the bicontinuous network structure. The gels were highly responsive to changes in pH of the medium and showed high-swelling degree in acidic media owing to the protonation of the tertiary nitrogen of the piperazine ring.
- 出版日期2009-4-15
- 单位南阳理工学院
