Conformational energy surfaces are determined as functions of torsional angles of bonds between rings for an ct-~t pyrrole trimer by using semiempirical quantum-mechanical calculations (AM1). Isomeric states for torsional rotations are identified as positions of minimum energy. Statistical weights determined on this basis are used in calculating the average dimensions of polypyrrole chains by the rotational isomeric state (RIS) model and the matrix multiplication scheme. Results of calculations indicate that the chains have unusually large characteristic ratios and persistence lengths with very strong temperature dependence. Characteristic ratios obtained by the RIS model show perfect agreement, in a wide temperature range, with the predictions of the worm-like chain model.
Посилання на статтю:
Configurational properties of polypyrrole chains / Ersin Yurtsever and Burak Erman* // Polymer. – 1993. – Vol 34. – P. 3887-3892.