Abstract :
Ar plasma etched and Al metallised bisphenol A carbonate was analysed by mass spectroscopy, photoelectron
spectroscopy XPS., and scanning force microscopy SFM.. We mainly used a technical polymer Makrolon 2808, Bayer.
made by injection-moulding, as well as spin coated bisphenol A carbonate ns1.and polycarbonate PC. ns115.. The
mass spectroscopy during the etching process shows the degradation of the PC in the form of carbon monoxide, carbon
dioxide and methyl groups. The photoelectron spectroscopy shows in detail the surface modification after Ar plasma
treatment and metallisation. The plasma induces a reduction of the carboxylic carbon C 1s., a strong reduction of singly
bonded oxygen O 1s.and also a slight reduction of doubly bonded oxygen. After Al metallisation, a reaction of Al with the
oxygen groups and an interaction with the aromatic system is documented. Ar plasma etching increases the chemical
interaction of Al mainly with the aromatic carbon. The X-ray photoelectron spectroscopy of metallised PC under different
initial conditions shows a strong influence of incorporated water in the PC bulk that cannot be seen by XPS on uncoated PC.
The O 1s signal increases during metallisation and results in an oxidation of Al probably caused by the fact that the
hydrophobic surfaces becomes hydrophillic. Temperature-dependent XPS was done on technical PC samples and on spin
coated samples ns1, ns115.and supports the influence of the bulk state for the Al–PC interface. For ns1 carbonate, a
diffusion of Al into the PC volume was observed. The SFM measurements showed a roughening effect on the nanometer
scale even after short treatment times. Al can be seen as a weakly bound cluster on the virgin PC, and if a pre-etching is
done, Al seems to grow as a good wetting film. The adhesion force of Al films on PC without any influence of the volume
can be explained by the chemical bonding of Al to the carboxylic and aromatic systems. The adhesion can be increased by
plasma pre-treatment. A breakdown of the adhesion on technical PC is probably induced by a reaction of Al with mobile
intercalated gas, that is enriched near the surface after Al coating. q1999 Elsevier Science B.V. All rights reserved
Keywords :
polycarbonate , Plasma , AR , XPS , mass spectroscopy , SFM
