Ordering transitions of weakly anisotropic hard rods in narrow slit-like pores

Abstract

The effect of strong confinement on the positional and orientational ordering is examined in a system of hard rectangular rods with length L and diameter D (L>D) using the Parsons-Lee modification of the second virial density functional theory. The rods are nonmesogenic (L/D<3)and confined between two parallel hard walls, where the width of the pore (H) is chosen in such a way that both planar (particle's long axis parallel to the walls) and homeotropic (particle's long axis perpendicular to the walls) orderings are possible and a maximum of two layers are allowed to form in the pore. In the extreme confinement limit of ,where only one layer structures appear, we observe a structural transition from a planar to a homeotropic fluid layer with increasing density, which becomes sharper as L->H. In wider pores (2D<H<3D) planar order with two layers, homeotropic order, and even combined bilayer structures (one layer is homeotropic, while the other is planar) can be stabilized at high densities. Moreover, first order phase transitions can be seen between different structures. One of them emerges between a monolayer and a bilayer with planar orders at relatively low packing fractions.

arXiv comment20 pages, 5 figures

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Cited by in corpus (5)

• Orientational ordering and layering of hard plates in narrow slit-like pores
• Biaxial layering transition of hard rod-like particles in narrow slit-like pores
• From n-layer planar ordering to the monolayer homeotropic structure of confined hard rods: The effect of shape anisotropy and wall-to-wall separation
• Confinement effects on the random sequential adsorption packings of elongated particles in a slit
• Capillary-driven biaxial planar and homeotropic nematization of hard cylinders