X-ray photoelectron spectroscopy (XPS) has been used to investigate the surface characteristics of various novel fluorinated acrylate homopolymers [1,1-dihydroperfluorooctyl acrylate (PFOA), 1,1-dihydroperfluorooctyl methacrylate (PFOMA), 1,1,2,2-tetrahydroperfluorooctyl acrylate (PTAN)] as well as diblock copolymers consisting of both a fluorocarbon block of PFOA and a hydrocarbon block of polystyrene (PS). This technique allows nondestructive depth profiling of the top ∼100 Å of a material, providing both elemental composition and chemical state information. Due to the low surface energy of the fluorinated species, its enhanced presence on the surface is of importance in any potential applications. Angle-dependent XPS surface studies were conducted on polymer thick films to monitor surface segregation of the fluorinated component as a function of depth. Fluorine and the fluorine-containing constituents are surface enriched relative to carbon and oxygen from the acrylate portions of the polymers. This effect also occurs in the diblock copolymers, where the PFOA block prefers the polymer−air interface. Furthermore, this surface segregation is enhanced when the samples are thermally annealed. Also, the quantitative XPS data reveal other subtleties in the overall polymer structures, such as extent of chain branching in PFOA, PFOMA, and the diblock copolymers and the slight variations in average fluorine-containing side chain lengths in PTAN.

Homogeneous and stable layers were deposited through allylamine plasma polymerization (75 W, 100 Pa, 15 min) onto poly[(3-hydroxybutyric acid)-co-(3-hydroxyvaleric acid)] (91 : 9 wt.-%) (P(HB-co-9%HV)) film surfaces. XPS analysis using take-off angles of 20" and 70" and performed 10 days and 20 days after plasma treatment gives information on the composition (in atom %) of the modified surface: C, 62.74; N, 19.60; 0, 17.65. The unexpected oxygen percentage is weaker if argon plasma pretreatment (25 W, 40 Pa, 5 min) is applied. Then, a succinct mechanism is proposed. The study of changes in element ratios and binding energy values shows that the majority of incorporated functional groups seem to be amide and imine groups.

Sample preparation, namely finding a suitable matrix-analyte combination, has been one of the most important concerns in using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for synthetic polymers. Herein we report the novel use of surfactants in the polymer sample preparation procedure. Specifically, three nonionic surfactants were investigated for MALDI analysis of poly(methyl methacrylate) (PMMA). This approach resulted in major enhancements in the PMMA molecular ion signals with dithranol as the matrix. The results illustrate the importance of polymer-matrix miscibility in optimizing MALDI investigations.

Plasma polymerization of allylamine, acrylic acid, and an allylamine/acrylic acid mixture on Silastic silicone rubber led to a strong increase in the silicone rubber's hydrophilicity and surface energy. Analysis of the deposited layer by X-ray photoelectron spectroscopy with 20°and 70°takeoff angles showed segregation of the atoms according to the depth and the incorporation of amino groups, oxygenated groups, and both. The endothelialization of untreated and treated samples was evaluated by the seeding and growth of aorta epithelial cells from pigs in cellular adherence (%), doubling time (in hours), and confluent density (10 4 cells/cm 2 ). The best results were obtained with the allylamine/acrylic acid mixture treatment, which brought a biocompatibility to Silastic similar to classic tissue culture on polystyrene plates. The interpretation was based on the presence of NH 3 ϩ /CO 2Ϫ microareas in the deposited layer.

Poly[(3-hydroxybutyric acid)-co-(3-hydroxyvaleric acid)](91 : 9 mass-%) (P(HB-co-9% HV)) film surfaces were modified by an oxygen plasma treatment (75 W, 50 Pa, 5 min). The number of oxygen atoms increases about 12-13% and the polar component of the surface energy increases from 6.3 to 21 mN-m-'. However, the wettability is stable only after 60 days. Untreated and treated film surfaces are studied by means of X-ray photoelectron spectroscopy with two different depth analyses. With storage time, the oxygen contents of the modified film is constant at a take-off angle of 20" but decreases to the initial value at a take-off angle of 70". The superficial layer of the polymer film between the top of the film to a depth of 10 nm is divided into three superimposing zones. The interpretation is supported by motions of modified macromolecular chains and buried polar groups, chain cleavage and the formation of low-molecular-weight molecules which leads to a decrease of the glass transition temperature (plasticizer effect) and migration of short chains from the lowest modified zone toward the surface.