Theoretical calculation of conformational energies of polytetrafluoroethylene

摘要

The predictions of three sets of nonbonded steric energy parameters for the low‐temperature structure of polytetrafluoroethylene (PTFE) are compared. The free energy and the distribution of torsional angles are also calculated for all three sets using the transfer‐matrix (TM) method. The two‐near‐neighbor approximation normally used is found to be inadequate, and the TM method is modified to include interactions out to four near neighbors. All three parameter sets are found to predict helical conformations at low temperature, but the predicted pitch does not agree with the experimentally determined pitch. Some comments are presented on the applicability of the parameter sets for an investigation of the interchain interactions and the solid‐state phase transitions in PTFE.