The mixing effect of amine and carboxyl groups on electrorheological properties and its analysis by in situ FT-IR under an electric fieldElectronic supplementary information (ESI) available: Additional electrorheological data, FT-IR spectra, TGA curves and electrical data. See DOI: 10.1039/c3cp51907d

• Main Authors: Ko, Young Gun, Lee, Hyun Jeong, Park, Yong Sung, Woo, Je Wan, Choi, Ung Su
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c3cp51907d

Herein, the mixing effect of amine and carboxyl groups on electrorheological (ER) properties has been presented with the chitosan and alginic acid dispersed suspensions. Chitosan (for the amine group) and alginic acid (for the carboxyl group) are used to investigate the mixing effect of the amine and carboxyl groups on ER properties with the control of their mixing ratio in the silicone oil. The surface-chemical structure of the mixture of the chitosan and alginic acid particles in the silicone oil is demonstrated by in situ Fourier transform infrared (FT-IR) spectroscopy at various electric fields for the first time. This study focuses on whether the mixture of chemical groups in the ER fluid can promote ER properties or not, and in situ FT-IR analysis of the interface between ER particles in the silicone oil at various DC electric fields. The ER fluids exhibited the increase of the yield stress values with the increase of the counter group addition up to the weight ratio of 50 : 50 (chitosan : alginic acid). A noteworthy result is that the mixing effect of the amine and carboxyl groups resulting in enhanced ER properties is clearly proved. In the in situ FT-IR study, the complex form of amine and carboxyl groups of particles in the ER fluid was confirmed under the electric field. The surface-chemical structure of aligned chitosan-alginic acid particles in the silicone oil under the DC electric field is demonstrated by in situ FT-IR.