UV-INDUCED REACTIVITY OF LINOLEIC-ACID MONOLAYERS - THE INFLUENCE OF SUBPHASE CONDITIONS

The dependence on surface pressure and subphase composition of the rea ctivity of linoleic acid monolayers has been investigated. The highest reaction rates were observed for 10(-4) M AlCl3 at pH 4.8 and 10(-4) M TbCl3 at pH 6.9, while the presence of either Pb(NO)(2) or ZnCl2 res ulted in a rather low reaction rate. The ions could be ordered with in creasing interaction with the monolayer as Zn2+ < Pb2+ < Tb3+ < Al3+. The reaction kinetics of the floating monolayer suggested that the rea ction was first order at a surface pressure of 15 mN m(-1). At surface pressures below 12.5 mN m(-1) the reaction rate was greatly reduced. Multilayer structures of both the monomer and the reacted monolayer co uld be built up which allowed both ATR-FTIR and AFM analysis to be car ried out. Clear irradiation-induced changes in the topographical struc ture occured during the course of the reaction as evidenced by AFM stu dies of the Langmuir-Blodgett multilayer structures.