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

Solutions of chain‐ (PS‐ d 3 ) and phenyl ring (PS‐ d 5 ) deuterated polystyrenes in perdeuterated PS‐ d 8 have been investigated with 1 H and 2 D NMR relaxation and wide line methods. The intra‐ and intermolecular parts of the 1 H second moments at −100°C are 3,7 G 2 and 2,0 G 2 , respectively, for PS‐ d 3 , and 14,7 G 2 and ca. 0 G 2 , respectively, for PS‐ d 5 . The intermolecular contribution to the 1 H spin lattice relaxation rate, determined at 55 MHz between 150°C and 250°C, is about one third of the total rate in PS‐ d 3 , and negligible in PS‐ d 5 . We suggest that this contribution is caused by rotational fluctuations of the intermolecular H ⃛H vectors. The intramolecular 1 H‐ and 2 D‐relaxation rates indicate that the phenyl group motion is somewhat faster than the rotational segmental motion of the polymer chain.