SPREADING BEHAVIOR OF POLY(N-DODECYLACRYLAMIDE-CO-STYRENE) MONOLAYERS AND LANGMUIR-BLODGETT MULTILAYER FORMATION

The spreading behavior of poly(N-dodecylacrylamide-co-styrene)s (PDDASt) with various copolymer compositions on a water surface was investigated by measurements of the surface pressure (pi)-area (A) isotherms. The stability of the copolymer monolayers depends strongly on the styrene (St) content in the copolymers; the monolayer becomes unstable, and the collapse pressure in the pi-A isotherms decreases linearly as the styrene mole fraction increases. A closely packed condensed monolayer was formed for copolymers having a styrene content up to 0.6 mole fraction. This is due to the excellent monolayer formation property of the N-dodecylacrylamide (DDA) monomer unit. A linear relationship between the average limiting surface area per monomer unit and the styrene mole fraction is observed, indicating that additivity of the surface area of DDA and St holds; that is, DDA and St monomer units are mixed, with each having its own surface area, 0.28 and 0.16 nm2, respectively, in the copolymer monolayers on water. This corresponds to an ideal mixing. The condensed polymer monolayers could be transferred successively onto solid supports such as a quartz slide by both downward and upward strokes with a transfer ratio of unity, giving Y-type uniform polymer LB films having an aromatic moiety applicable to various functionalities. An extension to a method for the introduction of various useful functional comonomers into the polymer LB films is also described.