Particle beam-induced reactions versus thermal degradation in PMDA-ODA polyimide

Abstract

Chemical reactions induced by heat and particle bombardment at low energy in PMDA-ODA have been studied by XPS and REELS. Different chemical reactions involving the chemical state of oxygen and nitrogen are shown to occur with different products and rates depending on the peculiar way of energy deposition. In particular, thermal treatments proceed mainly by decarbonylation of imidic rings, leaving the ether linkage in the PMDA-ODA unit essentially unaffected. Evidence is found that thermal treatment results in the formation of large condensed aromatic systems, possible precursors for true graphitization at higher temperature. Also, a characteristic REELS signature is observed, diagnostic of the formation of a hydrogenated amorphous carbon phase. In the case of particle bombardment, the destruction of imide and phenyl rings occurs through a random fragmentation mechanism, leaving a detectable concentration of the imidic moiety at the steady state. A specific reaction channel has been identified, involving the production of recoiling oxygen atoms, which react with the carbon backbone to form new additional ether or hydroxyl groups. Also the electronic structure of the irradiated samples is shown to be different from that of the pyrolyzed samples. In particular, no evidence is found for the formation of large delocalized aromatic systems observed in the thermal case, while the predominant effect is the formation of highly disordered a-C:H phases.

Investigation of Surface Etching of Poly(Ether Ether Ketone) by Atmospheric-Pressure Plasmas

“…Consequently, it might be assumed that there is no indication of ring opening by cleavage of the aromatic structure after plasma treatment. Therefore, due to the stability of etherlike bonds, which is attributed to the high radiation resistance of the ether linkage stabilized by the two contiguous benzene rings [27], it is most likely that the oxygen incorporation occurs into the benzene rings [28]. According to these results, the changes in the chemical structure of PEEK are discussed hereinafter.…”

Physico-chemical characteristics of high performance polymer modified by low and atmospheric pressure plasma

“…Inagaki et al [8] studied PEEK surfaces modified by using remote oxygen plasma and observed that degradation products were formed on the PEEK surface by the oxygen plasma treatment. The formation of new groups on the surface of PEEK after plasma treatment is attributed to the depletion of hydrocarbon in the benzene ring and uptake of oxygen by polymer surface leading to the formation of C-O-C (or C-OH), C=O and O-C=O groups while the stability of the carbonylic component and the ether like bond is due to the high radiation resistance of linkages stabilized by two contiguous benzene rings [14,15].…”

Chemical degradation of polyimide and polysulfone films under the irradiation with heavy ions of several hundred meV

“…This reaction is not only known from the early stage of PI pyrolysis 37 but also from irradiation with ions in the keV energy regime. 38 …”