1H NMR and 2D NMR relaxation and wide line measurements in partially deuterated polystyrenes

Solutions of chain‐ (PS‐d3) and phenyl ring (PS‐d5) deuterated polystyrenes in perdeuterated PS‐d8 have been investigated with 1H and 2D NMR relaxation and wide line methods. The intra‐ and intermolecular parts of the 1H second moments at −100°C are 3,7 G2 and 2,0 G2, respectively, for PS‐d3, and 14,7 G2 and ca. 0 G2, respectively, for PS‐d5. The intermolecular contribution to the 1H spin lattice relaxation rate, determined at 55 MHz between 150°C and 250°C, is about one third of the total rate in PS‐d3, and negligible in PS‐d5. We suggest that this contribution is caused by rotational fluctuations of the intermolecular H ⃛H vectors. The intramolecular 1H‐ and 2D‐relaxation rates indicate that the phenyl group motion is somewhat faster than the rotational segmental motion of the polymer chain.