MOLECULAR-MOTION OF POLY(OXYMETHYLENE) IN SOLUTION

The molecular motion of poly(oxymethylene) in dilute phenol solution has been studied by using the coupled spin relaxation of a methylene group ((CH2)-C-13). Four unique spectral densities are measured. These are reexpressed in terms of second-rank correlation times. The ratio of tau-zz to tau-yy to tau-xy is 1.6:1:0.61. These anisotropies of motion are smaller than those measured for hydrocarbon chains in solution. Unlike the hydrocarbons, poly(oxymethylene) is most stable in the gauche conformer, which leads to helical chain configurations. The smaller anisotropy may reflect the lack of correlated motions of a few bonds in the polymer chain.