XPS STUDIES OF FLUORINATED ACRYLATE POLYMERS AND BLOCK-COPOLYMERS WITH POLYSTYRENE

X-ray photoelectron spectroscopy (XPS) has been used to investigate th e surface characteristics of various novel fluorinated acrylate homopo lymers [1,1-dihydroperfluorooctyl acrylate (PFOA), 1,1-dihydroperfluor ooctyl methacrylate (PFOMA), 1,1,2,2-tetrahydroperfluorooctyl acrylate (PTAN)] as well as diblock copolymers consisting of both a fluorocarb on block of PFOA and a hydrocarbon block of polystyrene (PS). This tec hnique allows nondestructive depth profiling of the top similar to 100 Angstrom of a material, providing both elemental composition and chem ical state information. Due to the low surface energy of the fluorinat ed species, its enhanced presence on the surface is of importance in a ny potential applications. Angle-dependent XPS surface studies were co nducted on polymer thick films to monitor surface segregation of the f luorinated component as a function of depth. Fluorine and the fluorine -containing constituents are surface enriched relative to carbon and o xygen from the acrylate portions of the polymers. This effect also occ urs in the diblock copolymers, where the PFOA block prefers the polyme r-air interface. Furthermore, this surface segregation is enhanced whe n the samples are thermally annealed. Also, the quantitative XPS data reveal other subtleties in the overall polymer structures, such as ext ent of chain branching in PFOA, PFOMA, and the diblock copolymers and the slight variations in average fluorine-containing side chain length s in PTAN.