Title: Liquid-gas phase behavior of polydisperse dipolar hard-sphere fluid: Extended thermodynamic perturbation theory for central force associating potential
Author(s):

	Yu.V. Kalyuzhnyi (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79011 Lviv, Ukraine) ,
	S. Hlushak (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79011 Lviv, Ukraine; Department of Chemical Engineering, Vanderbilt University, Nashville, Tennessee 37235) ,
	P.T. Cummings (Department of Chemical Engineering, Vanderbilt University, Nashville, Tennessee 37235; Nanomaterials Theory Institute, Center for Nanophase Material Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830)

The liquid-gas phase diagram for polydisperse dipolar hard-sphere fluid with polydispersity in the hard-sphere size and dipolar moment is calculated using extension of the recently proposed thermodynamic perturbation theory for central force (TPT-CF) associating potential. To establish the connection with the phase behavior of ferrocolloidal dispersions it is assumed that the dipole moment is proportional to the cube of the hard-sphere diameter. We present and discuss the full phase diagram, which includes cloud and shadow curves, binodals and distribution functions of the coexisting daughter phases at different degrees of the system polydispersity. In all cases studied polydispersity increases the region of the phase instability and shifts the critical point to the higher values of the temperature and density. The larger size particles always fractionate to the liquid phase and the smaller size particles tend to move to the gas phase. At relatively high values of the system polydispersity three-phase coexistence is observed.

Key words: TPT, associating fluid, polydispersity, ferrocolloids, phase diagram
PACS: 64.10.+h, 64.70.Fx, 82.70.Dd

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