MIXTURES OF ASSOCIATING AND NONASSOCIATING CHAINS ON ACTIVATED SURFACES - A MONTE-CARLO APPROACH

The behavior of mixtures of associating and non-associating chains con fined in pores with activated surfaces is studied by means of molecula r simulation. The fluid molecules are modeled as a chain of four tange nt Lennard-Jones spheres. Some of the chains have an additional associ ating square-well site placed in an end sphere. The activated surfaces of the slit pore are modeled via an integrated Lennard-Jones (10-4-3) potential with specific association sites protruding from the surface . We present Gibbs ensemble Monte Carlo simulation results for the par titioning of mixtures of chains in the bulk and confined phases for th is particular model. The chain-wall association governs the adsorption behavior of the system. The preferential adsorption of associating ch ains is seen to strongly depend on temperature and pore width. Selecti vities obtained are in the range of those seen in experiments of alkan e-alkanol mixtures.