Theoretical investigation on the conformation of ethylene-norbornene copolymer chains

The conformational analysis of ethylene-norbornene chains (E-N) has been carried out using AM1, MM2, AMBER and OPLS methods taking into consideration the possibility of binding the ethylene monomers to norbornene monomers at various positions, i.e. exo-exo, exo-endo, endo-endo. The chain that is formed by connecting exo-endo positions of the monomers has lower torsional barrier energy than those formed with bonds at other positions and has more flexibility. It has been determined that the lowest strain energy has also NEEN and NNEE tetrads. NEEN copolymer has the lowest strain energy according to the molecular mechanics methods. Using the molecular mechanics and semiempirical AM1 methods, 1-2-3-4 internal rotation angle (dihedral) (φ) for all E-N copolymers have been calculated.