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Angle‐resolved XPS of fluorinated and semi‐fluorinated side‐chain polymers
Author(s) -
Beamson G.,
Alexander M. R.
Publication year - 2004
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.1712
Subject(s) - x ray photoelectron spectroscopy , side chain , contact angle , polymer , surface energy , chemistry , crystallography , analytical chemistry (journal) , materials science , organic chemistry , physics , nuclear magnetic resonance , composite material
Angle‐resolved XPS data (elemental quantification and high‐energy‐resolution C 1s) are presented for ten polymers with side‐chains of the form OCO(CF 2 ) y F, COO(CH 2 ) 2 OCO(CF 2 ) y F ( y = 1, 2, 3) and COO(CH 2 ) x (CF 2 ) y F ( x = 1, y = 1, 2, 3; x = 2, y = 8). Particular attention was paid to charge compensation and speed of data acquisition, with co‐addition from multiple fresh samples to give spectra with good energy resolution and good signal‐to‐noise ratio free from the effects of x‐ray‐induced degradation. Water contact angles for the polymers are also reported. The XPS data demonstrate preferential surface segregation of fluorine‐containing groups for all but the shortest side‐chain polymer, where the OCOCF 3 side‐chain either does not surface segregate or is too short for surface segregation to be detectable by angle‐resolved XPS. In the other polymers studied the relative positions of functional groups in the side‐chains correlate with the angle‐resolved behaviour of the corresponding C 1s components. This shows that the surface side‐chains are oriented towards the polymer surface. For the COO(CH 2 ) 2 OCO(CF 2 ) y F ( y = 1) side‐chain, the angle‐resolved C 1s data suggest reduced ordering and linearity compared with y = 2 and 3. For any particular series of polymers, e.g. COO(CH 2 ) x (CF 2 ) y F, the water contact angles increase with y , consistent with burying of the hydrophilic ester groups as y increases. For any particular value of y the sequence of water contact angles is COO(CH 2 ) x (CF 2 ) y F > OCO(CF 2 ) y F ∼ COO(CH 2 ) 2 OCO(CF 2 ) y F, suggesting greater ordering and density of fluorocarbon species at the surface of the COO(CH 2 ) x (CF 2 ) y F side‐chain polymers compared with the other polymers studied. For the COO(CH 2 ) 2 (CF 2 ) 8 F polymer a water contact angle of 124° is measured, which is greater than that of poly(tetrafluoroethene). The COO(CH 2 ) 2 OCO(CF 2 )F polymer is unusual in that it shows a particularly low water contact angle (83° ), suggesting that the probe fluid is able to sense both ester groups, consistent with the reduced ordering of the side‐chain detected by angle‐resolved XPS. Copyright © 2004 John Wiley & Sons, Ltd.