Study on the effect of the organic acid structure on the rheological behavior and aggregate transformation of a pH-responsive wormlike micelle system. Issue 15 (13th March 2019)

• Record Type: Journal Article
• Authors: Kang, Wanli; Hou, Xiaoyu; Wang, Pengxiang; Zhao, Yilu; Zhu, Tongyu; Chen, Chao; Yang, Hongbin
• Is Part Of: Soft matter. Volume 15:Issue 15(2019)
• Page Start: 3160
• Page End: 3167
• Publication Date: 2019-03-13
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c9sm00088g
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : The effect of the organic acid structure on the rheological behaviour and aggregate transformation of a pH-responsive wormlike micelle system has been researched. Abstract : A worm-like micelle (WLM) system can be obtained by mixing long-chain cationic surfactants and polybasic organic acids in an aqueous solution. However, the effect of different organic acid structures on the rheological behavior of WLM systems has not been researched. Herein, a novel pH-responsive wormlike micelle system (EATA) was constructed by the complexation of N -erucamidopropyl- N, N -dimethylamine (UC22 AMPM) and benzene tricarboxylic acid (TA) at a molar ratio of 3 : 1. UC22 AMPM/citric acid (EACA) was also prepared to perform a comparison. The rheological behavior, aggregate transformation and thickening mechanism of EATA solutions were investigated by using rheological measurements, cryo-TEM, DLS, surface tension and 1 H NMR. The results show that, at low pH, spherical micelles were formed and the EATA solution exhibited a lower viscosity than the EACA system due to the strong hydrophobicity of the phenyl groups of TA molecules, but the viscosity reaches 10 6 mP s at pH 4.80. Because of the lower p K a value of TA than CA, the viscosity of the EATA system drops sharply with the appearance of precipitates caused by the isoelectric point when the pH is greater than 4.80. In addition, by circularly changing the pH value several times, the wormlike micelles could maintain their original viscoelasticity without being weakened in the slightest.