摘要: Proton decoupled, partially relaxed, Fourier-transform 50.3 MHz carbon-13 NMR in natural abundance was used to determine spin-lattice times (T1) and nuclear Overhauser enhancement fac-tors (NOE) of individual carbon of a serics of 1,2-polybutadienes with different structures in solutionin CDCl2. The structure dependence of molecular metion and the internal motion of vinyl group in 1,2-polybutadiene have been studied by nT1 and NOE values. The nT1 values of the carbons in cis-1,4-units are the highest and those of the carbons in 1,2-units are the lowest in three types of units in 1,2-polybutadiene.The nT1 values of carbons in the same unit become greater when the adjacent 1,2-units are replaced by 1,4-units,and nT1 values of the carbons in all units decrease sharply with the increase of content of 1,2-units in the polymers.The fact that nT1 values of —CH=are larger than those of =CH2 in vinyl group implies that there are complex internal motions of vinyl group.It is shown by calculation that the dominant factor causing the difference in nT1 of—CH=and=CH2 in vinyl group is a swing of vinyl group in a plane perpendicular to the chain backbone.