UNORIENTED ADSORPTION OF SPHEROIDAL PARTICLES

Localized adsorption of non-interacting (hard) spheroidal particles on homogeneous interfaces was analysed theoretically. In contrast to pre vious studies, the unoriented (quasi 3D) adsorption was considered. By applying the random sequential adsorption (RSA) approach, asymptotic analytic expressions were derived for the surface blocking parameter B (available surface function) in the limit of low and moderate surface concentrations. The range of validity of the approximate analytical r esults was determined by numerical simulations of adsorption kinetics performed for prolate spheroids using the Monte-Carlo (MC) RSA simulat ion technique. It was revealed by this comparison that the analytical approximation can be used with a good accuracy for surface concentrati ons smaller than 0.5. The numerical calculations enabled also to deter mine the maximum (jamming) surface concentrations for unoriented adsor ption of spheroids as a function of the elongation parameter A. It was demonstrated that the jamming concentrations theta(infinity) are appr oached for long adsorption times as tau(-1/4), and the system deviates therefore considerably from the Langmuir model used often in the lite rature.