Surface characterization and study of Langmuir films of poly(4-vinylpyridine) quaternized with n-alkylbromide

The surface behaviour of poly(4-vinylpyridine)s (P4VP) quaternized with fou r different alkyl chains (pentyl, hexyl, octyl and decy bromide) were studi ed. Surface pressure-area isotherms (pi -A) at the air-water interface were determined. Depending on the length of the side-chains, the pi -A isotherm s show a plateau region. An extensive plateau is observed for n >6. The pla teau pressures are similar for n = 8 and n = 10. The monolayers are stable and exhibit hysteresis phenomena. Brewster angle microscopy (BAM) is used t o monitor the monolayer topography of the polymer on water subphase. To obt ain information about the surface energy (SE) and the degree of hydrophobic ity of these systems, we have estimated the critical surface tension, gamma (c), and the dispersion force and polar contributions to SE, gamma (D) and gamma (P), respectively, by measurements of the contact angle (CA) of wate r and bromobenzene on the polymer surface. The results obtained are depend on the length of the alkyl lateral chain of the functionalized polymers. (C ) 2001 Society of Chemical Industry.