Liquid state NMR studies of polymer dynamics and conformation

Nuclear magnetic resonance experiments can reveal not only the chemical structures of polymers, together with their defects, but also a wealth of detail concerning their conformations and their motions. The local conformations combine to determine the bulk coiling properties of the polymer, such as the radius of gyration and hydrodynamic volume. They may be treated in a simplified way as a finite number of rotationally isomeric states. The presence and the weighting of these states may be approximately deduced either from computer modelling, or from fits to coiling properties, or from a number of theories which relate the local conformation to chemical shift, in a way that depends upon local tacticity. Further information about them may be available from spin-spin (J) couplings. This is because the size of three-bond and longer range spin-spin couplings depends on the dihedral angles between the bonds to the nuclei under observation. NOEs between vicial protons depend on local dihedral angles in a similar way.