Computational Chemistry on Internal Structures and Rheological Properties of Functional Colloids in Non-equilibrium Fields

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(1) We have discussed the cluster-based Stokesian dynamics method for non-dilute colloidal dispersions. The cluster-based method can drastically reduce the computation time, and, therefore, it is significantly superior to the ordinary SD method for ferromagnetic colloidal dispersions.(2) We have investigated the validity of the dissipative particle dynamics method, which is a mesoscopic simulation technique. We have derived expressions for transport coefficients such as viscosity, from the equation of motion of the dissipative particles. It is clarified from non-equilibrium dynamics simulations that the theoretical values of the viscosity due to dissipative forces are in good agreement with the simulation results obtained by the non equilibrium dynamics method, except in the range of small number densities and, therefore, that the present method is a hopeful technique for taking into account hydrodynamic interactions among colloidal particles.(3) We have also investigated the validity … More of the dissipative particle dynamics method for a dispersion composed of magnetic and dissipative particles. Various models as an interaction between these two different particles have been discussed and we have a conclusion that results are not significantly dependent on the interaction model.(4) We have theoretically investigated the particle orientational distribution and viscosity of a dense colloidal dispersion composed of ferromagnetic spherocylinder particles under circumstances of an applied magnetic field. The mean field approximation has been applied to take into account the magnetic interactions of the particle of interest with the other ones which belong to the neighboring clusters, besides its own cluster. It is clarified from solving the basic equation of the orientational distribution function, which is an integro-differential equation, by Galerkin's method and the method of successive approximation that, even when the magnetic interaction between particles is of the order of the thermal energy, the effect of particle-particle interactions on the viscosity comes to increase more significantly with increasing the volumetric fraction of particles. Less