Viscous Properties Of Nematics Liquid Crystals Composed Of Biaxial Molecules

From 1995 to 1998, Marcin Fialkowski have extensively studied the viscosity of nematic Liquid crystals composed of biaxial molecules.He presents a mean-field methed of obtaining the Leslie viscosity coefficients of biaxisl nematic liquid crystals.The viscosities presented are expressed by suspension parameters such as second- and forth-rank order parameters,three diffusion constants,temperature,number density and certain factors depending on the shapes of the molecules.Within London's dispersion forces approximation, potential parameterλ=γ~2.λdescribe the molecular biaxiality . The parameter have relation with the symmetry axes of the ellipsoids, a ,b and c.Within the Dielectric shape dispersion ,potential parameterλ≠0,γ= 0.There is no relation between molecular biaxial parameterλand the shape of molecular( a , b, c)we calculated the Leslie viscosity and rotational viscosity of biaxial nematic liquid crystal within the dispersion forces approximation. we calculated the Leslie viscosity and rotational viscosity of biaxial nematic liquid crystal within the Dielectric shape dispersion. we studied the relation of rotational viscosity of biaxial nematic liquid crystal and the shape of molecular ( a , b, c ),and the relation with parameterλ.