Plasma polymer adhesion promoters for metal-polymer systems - Polyimides and Other High Temperature Polymers - page 364

3. RESULTS

3.1. Extended chain-building plasma polymers
The general aspects of pulsed plasma polymerisation of vinyl and acrylic mono-
mers have been discussed elsewhere [1, 33, 40, 41]. In this communication the
polymerisation of styrene as a model for a chain extended plasma polymer is con-
sidered. Styrene as a vinyl monomer can easily undergo radical gas phase polym-
erisation in the plasma-off period. This behaviour is shown by the respective XPS
and NEXAFS spectra of pulsed plasma polymerised films (Figs. 3, 4). The spectra
of a commercial polystyrene standard sample and that obtained with pulsed
plasma polymerised styrene are almost identical. As known, the spectra represent
predominantly the primary chemical structure of both polymer materials. Detailed
assignments of peaks and resonance positions were reported in refs. [42, 43]. The
NEXAFS C K-edge spectrum of the pulsed plasma polymerised styrene is slightly
broadened due to branching and crosslinking in the film. Plasma polymers formed
from 1,3-butadiene present a NEXAFS spectrum different from that of the chemi-
cally polymerised butadiene. Here, the observed C1s →π * resonance can be as-

signed to non-saturated carbon species.

Figure 3. C1s signal, shake-up satellite and valence band spectra of a pulsed plasma polystyrene (30
W, 25 Pa, 10 3 Hz, duty cycle 0.1) and a commercial polystyrene as reference.