ADSORPTION-ISOTHERMS OF ASSOCIATING CHAIN MOLECULES FROM MONTE-CARLO SIMULATIONS

The inhomogeneous behaviour of associating chain fluids is studied by molecular simulation. The fluid molecules are modelled as a chain of f our tangentially bonded Lennard-Jones spheres with an associating squa re-well site placed at an end sphere. Adsorption isotherms between a b ulk phase and a system confined between two parallel structureless wal ls are obtained using the Gibbs ensemble Monte Carlo technique. Walls and molecules with and without associating sites, different pore width s and different solid-fluid interactions are considered. For surfaces without associating sites, the adsorption is seen to be governed by th e solid-fluid interactions of the molecules rather than by the molecul es ability or inability to self-associate. The number density of assoc iating sites placed on the walls strongly influences the adsorption ch aracteristics of these molecules.