Theory of structural phase transitions in crystalline poly(vinylidene fluoride)

A mean-field theory capable of predicting structural phase transitions in a linear polymer is presented. The intrachain and interchain potentials, derived from conformational analysis based upon molecular mechanics, are combined in a transfer–integral approach to calculate free energies as a function of temperature and applied uniaxial stress. The theory is applied to poly(vinylidene fluoride) and is successful in yielding several observed phases of this material and in predicting the effect of uniaxial stress on the most stable phase. There are no adjustable parameters in the theory.