Zur copolymerisation von α-methylstyrol und butadien III. Das NMR-spektrum der sequenzen mit zentraler α-methylstyroleinheit

220 MHz proton resonance spectra of copolymers from α-methylstyrene and butadiene have been investigated. Model compounds have been prepared by a lithiumbutyl initiated copolymerisation in tetrahydrofurane at ?75°C. The NMR spectra of the phenyl and α-methyl group are interpreted by signals from configurational and compositional triads with a central χ-methylstyrene unit. The chemical shift of the triads, possessing a central α-methyl styrene unit, takes place to lower field in the α-methyl region to such an extend that no strong overlapping with the signals of the configurational triads takes place. In the region of the phenyl protons configurational and compositional triads are overlapping each other. Using 3,4,5-trideuterio-α-methylstyrene it is possible to assign configurational and compositional triads in the resonance spectrum of the ortho-phenylprotons.