SELF-ASSEMBLY OF PHOTOPOLYMERIZABLE BOLAFORM AMPHIPHILE MONOLAYERS AND MULTILAYERS

Mono- and multilayers of photopolymerizable bolaform amphiphiles and p olyelectrolytes self-assembled onto mica from aqueous solution were st udied by surface force measurement and atomic force microscopy. Multip le layers of positively charged amphiphiles self-assemble if a negativ ely charged polyelectrolyte is inserted between them. The layers can b e photopolymerized with a high-pressure UV lamp. The atomic force micr oscopy images indicate that the photopolymerized amphiphile monolayer has a higher degree of order than the unpolymerized monolayer, althoug h the latter possesses some long-range order. Mechanical properties of the system measured by the surface force apparatus indicate that a ph otopolymerized layer is more robust and demonstrate that the rigidity and integrity of the first anchoring layer greatly influence the stabi lity of the multilayer. The interaction between polyelectrolyte layers in water can be either attractive or repulsive depending on the cover age of the polyelectrolyte on the amphiphile layer. The mica separatio n of a pair of opposed monolayers in contact in the presence of water is surprisingly small (25 angstrom) compared to the thickness (78 angs trom) of a bilayer composed of fully extended amphiphiles.