Langmuir, Vol.15, No.5, 1725-1730, 1999
Static and dynamic properties of calixarene monolayers at the air/water interface. 2. Effects of ionic interactions with p-dioctadecanoylcalix[4] arene
The static and dynamic properties of p-dioctadecanoylcalix[4] arene monolayers on the air/water interface are examined relative to the effects of inorganic and polymeric counterions (i.e., spermine, poly(ethylenimine), and poly(L-lysine)) in the subphase over a large range of pH. The methods adopted are the techniques of the Wilhelmy plate and surface light scattering (SLS). At moderate subphase pH values, 3.5-10, the polyions significantly expand the monolayer but do nut appreciably change the monolayer surface viscoelasticity as detected by SLS. A scheme of complex formation and acid-base equilibrium is used to explain the surface pressure isotherms while strong lateral packing interactions of the hydrophobic chains and aromatic rings, which predominate over the electrostatic interactions of the phenoxide rings of calixarene, are invoked to explicate the viscoelastic properties. Simple univalent inorganic ions do not show any specific effects on either the static or dynamic properties of these monolayers.
Keywords:LANGMUIR-BLODGETT-FILMS;PERFORATED MONOLAYERS;WATER;CALIX<4>ARENE;STABILIZATION;AMPHIPHILES;SCATTERING;COMPLEXES