1976 年 96 巻 7 号 p. 880-885
Some aromatic hydrocarbons, such as benzene, toluene, ethylbenzene, p-xylene, and styrene, were polymerized by subjecting them to a radio-frequency glow discharge at a reduced pressure (plasma polymerization), resulting in any of three types of products : powder, oil, and solid film, under varied plasma conditions. The oily products soluble in chloroform and carbon tetrachloride exhibited an average molecular weight of 400-600. The infrared spectra of these materials showed similar characteristics and also similar to normal polystyrene having a linear backbone chain, whereas their nuclear magnetic resonance (NMR) spectra did not show resemblance to the latter. NMR spectra of these products showed the presence of aromatic protons, widely shifted aliphatic protons, and olefinic protons, and the comparison of signal intensities of the polymer products with that of monomers suggested the formation of aliphatic chains derived from the cleavage of the aromatic rings. Based on these spectral data, structure of the oily products is postulated to be a polystyrene type but to have longer and branched backbone chains involving some double bonds. By assuming 1.5 hydrogen atoms to be bonded to a chain carbon, as in the normal polystyrene, the number of backbone chain carbons per benzene ring should be about four. Values of H/C ratio calculated from this assumption agreed well with that obtained from elemental analysis.