The ratio of a dimensional characteristic of a macromolecule in a given solvent at a given temperature to the same dimensional characteristic in the \(\unicode[Times]{x3B8}\) state at the same temperature. The most frequently used expansion factors are: expansion factor of the mean-square end-to-end distance, \(\alpha _{r} = \sqrt{\frac{ < r^{2} > }{< r^{2} >_{0}}}\); expansion factor of the @R05121@ \(\alpha _{s} = \sqrt{\frac{ < s^{2} > }{ < s^{2} >_{0}}}\); @V06627@ expansion factor \(\alpha _{\eta } = (\frac{\left[\eta \right]}{\left[\eta \right]_{\unicode[Times]{x3B8} }})^{\frac{1}{3}}\) where \([\eta]\) and \([\eta]_{\uptheta}\) are the intrinsic @V06627@ in a given solvent and in the \(\unicode[Times]{x3B8}\) state at the same temperature, respectively. Expansion factors defined by different dimensional characteristics are not exactly equal, nor need they have a constant ratio as a function of @R05271@.