The role of adsorbed water on TiO2 particles in the electrorheological effect

Zhaohui Qiu,Xiaoyi Wu,Rong Shen,Ying Wang,Kunquan Lu,Jing Huang,Xiaomin Xiong

doi:10.1063/1.5053165

Zhaohui Qiu, Xiaoyi Wu + Show 5 more

Open Access

https://doi.org/10.1063/1.5053165

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Abstract

TiO2 particles prepared by the hydrolysis of titanium butoxide adsorb water molecules with different adsorption energies. The electrorheological (ER) fluid composed of TiO2 particles behaves as the polar-molecule giant electrorheological (GER) fluid at 25°C even after thermal treatment at 75°C. After thermal treatment at 125°C and 175°C, the water molecules with low adsorption energy are removed and the ER fluid behaves as traditional ER fluid at 25°C. However, at 175°C, the ER fluid treated at 175°C behaves as a polar-molecule GER fluid when the external electric field is larger than 2 kV/mm. These results show that the water molecules with low adsorption energy act as polar molecules responsible for the GER effect and, with the help of thermal energy, water molecules with high adsorption energy can work as those with low adsorption energy, resulting in the GER effect.

Highlights

Water can remarkably enhance the performance of ER fluids, it increases the current density and reduces the electrical breakdown resistance, significantly limiting their application
In the preparation of the giant ER (GER) fluids containing polar molecules, water is often used as a solvent or reactant, which makes the presence of water unavoidable in these fluids.[13,14,17]
Do adsorbed water molecules with different adsorption energies have the same influence on the behavior of GER fluids in electric fields, i.e., do they contribute to the increase in yield stress? To the authors’ knowledge, these questions have not been addressed

Summary

Introduction

An electrorheological (ER) fluid, a type of smart material, is a suspension composed of dielectric particles and isolating oil that has a broad range of potential applications in dampers, microfluids, etc.[1,2,3,4,5] Since Winslow invented ER fluids in 1947,6 water has been found to be extremely important, with early traditional ER fluids containing water.[7,8] water can remarkably enhance the performance of ER fluids, it increases the current density and reduces the electrical breakdown resistance, significantly limiting their application.

Results

Conclusion