Disorder in paraffin chains of urea adducts and n-paraffins

In urea adducts with n-paraffins, the dependence of the rotational transition temperature on the chain length is analyzed, assuming that the paraffin molecules are in the all-trans conformation in the low temperature phase and contain conformational defects in the high temperature phase. The nature of the conformational defect is discussed on the basis of the conformational energy calculated. It is found that the conformational defect is a 60° twist and can be expressed as a soliton. The rotational phase transition of pure paraffins can be treated in the same manner as that of the urea adducts.