Pyrolysis mass spectrometry and gas chromatography of plasma‐polymerized benzene and xylene

Pyrolysis mass spectra and gas chromatograms of plasma‐polymerized benzene (PPB) and p‐xylene (PPX) have been studied. Both polymers gave mass spectra that indicated the presence of disubstitution in an aromatic ring and of product molecules, such as biphenyl and ethylbenzene, trapped in the polymer matrix. The PPB spectrum showed fragments originating from C6H4n structures and the PPX spectrum fragments originated from CH2C6H4CH2n structures. Both the pyrolysis mass spectrum and chromatogram contained peaks that distinguished PPX from commercial polystyrene samples. A chain mechanism which involves H abstraction reactions under plasma activation is proposed. The highly crosslinked structures of the polymers are attributed to the subsequent addition of free radicals to the double bonds of a fragmented chain formed as a result of the scission of the CC aromatic bond(s).