Plasma polymer adhesion promoters for metal-polymer systems - Polyimides and Other High Temperature Polymers - page 366

were observed in comparison to commercial PS [1]. Therefore, the most impor-
tant irregularities in the structure of pulsed plasma polystyrene are localized in the
backbone. Other non-vinyl chain-extending monomers such as 1,3-butadiene and
ethylene show a large number of indications for irregular structures in their IR
spectra also using pulsed or low power plasmas. As described in Section 3.2 they
pick up a large number of oxygen molecules from the air because of the existence
of trapped C radical sites. Other structures can be identified at 3300 ( ν≡ CH) and

2150 cm -1 ( C), at 1900 cm -1 (cumulene) as well as at 3060-3160, 1600, 1500,

760, 700 cm -1 (aromatic ring formation). However, the pulsed mode produces a
polyethylene whose structure is slightly closer to that of commercial polyethyl-
ene. A (very small)

ν C ≡

CH 2 vibration at 720 cm -1 was detected for the first time, in-
dicating the existence of at least two monomer units (

ρ

4)) in the pulsed
plasma polyethylene. So far such a vibration, characteristic of amorphous PE had
not described in the literature for ethylene plasma polymers (cf. [7, 8]). There is a
remarkable difference between the pulsed plasma polymerisation of a vinyl
monomer (styrene) and an olefin (ethylene) based on calculated polymerisation
degrees. Styrene shows a calculated polymerisation degree of

ρ CH 2 (n ≥

≥ 25 (e.g. 2600 Da)

[40, 41] and ethylene of ≈ 2.

Figure 5. ThFFF elugrams of unfiltered continuous wave and pulsed plasma polymerised polysty-
rene (MALLS - Multi Angle Laser Light Scattering detector; EASICAL - mixture of polystyrene
standards for calibrating).