Rw. Linton et al., TIME-OF-FLIGHT SECONDARY-ION MASS-SPECTROMETRIC ANALYSIS OF POLYMER SURFACES AND ADDITIVES, Surface and interface analysis, 20(12), 1993, pp. 991-999
This paper presents the application of static time-of-flight secondary
ion mass spectrometry (ToF-SIMS) to the analysis of polymeric materia
ls, including chemically modified polymers and polymer additives. Thro
ugh the detection of intact functionalized oligomers, analysis of poly
(styrene) functionalized with perfluoroalkyl chlorosilane provides con
firmation of a successful endgroup termination for a living polymeriza
tion. The calculated molecular weight distribution also is in good agr
eement with chromatographic results. High mass resolution studies allo
w monitoring of the hydrogenation of a poly(butadiene) polymer through
increases in oligomer mass due to proton addition. The quantitative T
oF-SIMS results for the extent of hydrogenation for a specific oligome
r are lower than the values averaged over all oligomers as determined
by magnetic resonance. The usefulness of ToF-SIMS for determination of
trace-level polymer additives is demonstrated for linear low-density
poly(ethylene) (LLDPE). Application of a 150 nm thick evaporated Ag pa
ttern enables in situ detection of the five trace additives present in
the LLDPE matrix, and also provides information on additive surface m
igration and surface oxidation. A study of the silver cationization pr
ocess for the silver-patterned LLDPE surface suggests differences in d
iffusion and/or ionization processes for two additives. This is confir
med with mass-resolved ion imaging to show the lateral distribution of
the silver-cationized signals for various polymer additive molecular
ions. Finally, poly(styrene) (M(n) = 1300) coated with a continuous si
lver overlayer is investigated. The ToF-SIMS-determined molecular weig
ht distribution shifts to lower masses, suggesting the greater diffusi
on of shorter polymer chains through the silver overlayer.