Self-assembly of poly(1,1-diethylsilabutane)-block-poly(2-hydroxyethyl methacrylate) block copolymer. 2. Monolayer at the air-water interface

A spread monolayer of the amphiphilic block polymer poly(1,1-diethylsilabut ane)-block-poly(2-hydroxyethyl methacrylate) (poly(SB-b-HEMA)) on the water surface was investigated by X-ray reflectivity (XR) measurements. Clear Ki essig fringes were observed up to the third order in the XR curve. This obs ervation means the formation of the smooth-faced monolayer with high unifor mity of thickness. The thickness of the monolayer increased with increasing surface pressure. Model filling with the two-layer model revealed that the upper layer is formed by the melt of the SE chains and that the lower laye r consists of hydrated HEMA chains. The flexibility of the SE chain is thou ght to be an origin for the formation of the smooth, dense, and variable-th ickness polymer monolayer on the water surface.