Statistical mechanics of an n-alkane chain in θ-condition: going beyond the RIS model

Abstract

Single n-alkane molecules in θ-conditions with lengths up to 200 monomers have been studied using realistic polymer models beginning with the RIS model. We show that the generalization to the continuous rotational potential model is essential for a quantitative description. Both models are solved (exactly and numerically efficiently) with an adaptation of the transfer matrix method to obtain the chain end distribution function, force-extension curve, structure factor and Kratky plot, mean square radius of gyration, and characteristic ratio. We test the results by using different sets of geometric and energetic parameters from the literature. We compare our results to other theoretical and also to experimental data. We also extract the Kuhn length using the Gibbs ensemble.