6533b852fe1ef96bd12ab673

RESEARCH PRODUCT

UV-Photometrische Analyse kationisch erzeugter Polystyrole, 2. Quantitative Bestimmung von Endgruppen in Polystyrolen, dargestellt mit Acylperchloraten

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Acyl perchlorates generated in styrene without a solvent by acyl chlorides and silver perchlorate gave polystyrenes with covalently bonded acyl groups. In order to gain secured values their number average relative molecular masses (Mn) were determined by different methods. The polystyrenes could be hydrogenated with hydrogen and Raney nickel at room temperature and under atmospheric pressure without attacking the phenolic nuclei. In addition IR data and a UV absorption at 294 nm of the polystyrenes revealed the presence of and olefinic bond, which was also found in a polystyrene obtained by polymerisation with perchloric acid. Also the quantitative evaluation of the hydrogeneation by UV absorption data gave number average relative molecular masses (Mn,H), which are in accordance with other Mn values. Furthermore, the UV absorption data of the polystyrenes gave correct Mn values (Mn,e) in combination with the molar absorption coefficients (e) of model compounds. The number of covalently bonded acyl groups in a polystyrene sample could be determined by quantitative measurement of the UV absorption in combination with the e-values of model compounds and the Mn values. This number was found to depend on the nature of the acyl perchlorate and it amounts to one acyl containing molecule per four to hundred molecules without an acyl group.