Surface characterization and study of Langmuir films of

The surface behaviour of poly(4-vinylpyridine)s (P4VP) quaternized with four different alkyl chains (pentyl, hexyl, octyl and decy bromide) were studied. Surface pressure-area isotherms (π-A) at the air-water interface were determined. Depending on the length of the side-chains, the π-A isotherms show a plateau region. An extensive plateau is observed for n>6. The plateau pressures are similar for n=8 and n=10. The monolayers are stable and exhibit hysteresis phenomena. Brewster angle microscopy (BAM) is used to monitor the monolayer topography of the polymer on the water subphase. To obtain information about the surface energy (SE) and the degree of hydrophobicity of these systems, we have estimated the critical surface tension, γ_c, and the dispersion force and polar contributions to SE, γ_D and γ_p, respectively, by measurements of the contact angle (CA) of water and bromobenzene on the polymer surface. The results obtained are depend on the length of the alkyl lateral chain of the functionalized polymers.