Carbon-13 and proton magnetic resonance studies of poly(N-vinylcarbazole) in solution

Spin-lattice relaxation times T₁ of individual carbons and protons were measured by the partially relaxed Fourier transform (PRFT) method for poly(N-vinylcarbazole) in solution. The ¹³C-T₁ value of the methylene carbon is about one-half of that of the methine carbon, and the carbazolyl CH carbons have T₁ values close to that of the skeletal CH carbons. The effective correlation time for the skeletal carbon is estimated as ca. 0,95 ns on the basis of the measured T₁ and ¹³C-¹H nuclear Overhauser effect (NOE) factor. Moreover, the ¹³C normal Fourier transformation (NFT) spectrum and proton T₁ indicate strong steric interactions between the pendant carbazolyl groups in the polymer. The results demonstrate that the polymer in solution has a rigid local structure with hindered internal rotation of the bulky side-chain groups.