Electrorheology of Suspensions of Copper Phthalocyanine-Doped Mesoporous Silica

Mesoporous silica(MPS) particles are synthesized in the presence of templates of surfactant micelles and the doping treatments are carried out to form copper phthalocyanine(CuPh)-doped MPS. The rheological properties of suspensions of CuPh-doped MPS particles dispersed in a silicone oil are studied on the application of DC electric fields. The electrorheological(ER) effect of CuPh suspensions is very weak, although the CuPh compounds are well known as semiconducting materials and widely used in industries. However, the doping of CuPh into MPS causes a drastic increase in ER effect and conductivity of suspensions. It is generally accepted that the interparticle forces generated in electric fields are polarization forces due to the dielectric mismatch between the particles and continuous liquid phases. In some cases, the surface conduction of thin layers on the particles can play an important role in promoting the ER effect. The increase in surface conduction by doped CuPh on the MPS may be responsible for enhancement of ER effect. The doping of semiconducting materials into mesoporous particles provides a new formulation method of excellent ER particles.