Predicting Chain Dimensions of Semiflexible Polymers from Dihedral Potentials

Abstract

We develop a numerical and an analytical approach to estimate the persistence length l p and mean-square end-to-end distance ⟨ R 2 ⟩ of complex semiflexible polymers. Numerically, l p and ⟨ R 2 ⟩ are determined by averaging a large set of single chain conformations with the correct dihedral angle distributions p (ϕ i ). Analytically, l p and ⟨ R 2 ⟩ are extracted from the tangent–tangent correlation function. We apply both approaches to two semiflexible conjugated polymers, poly(3-hexylthiophene) (P3HT) and poly((9,9-dioctylfluorene)-2,7-diyl- alt -[4,7-bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2′,2″-diyl) (PFTBT). Results obtained via the two methods agree for polymers with any degree of polymerization N . Our methods can be applied to any semiflexible polymers with any number of distinct moieties.