Thermodynamics and the equilibrium state of a binary copolymer that is determined by next‐nearest neighbor intrachain effects

Abstract

AbstractThe equilibrium state of an infinite molecular weight, binary copolymer which is determined by next‐nearest neighbor placements of its counits is defined in terms of the conditional probabilities describing such placements and the standard state free energies governing them. The combinatorial method is used to derive the entropy of sequence length distribution, ΔSD. When ΔSD is combined with an expression for the energy of reaction which employs the standard‐state free energies of triad formation an expression for the copolymer's free energy is obtained. Since enumeration of the interrelationships among the possible triplets reveal three independent conditional probabilities, separate differentiations with respect to each of three conditional probabilities are equated to zero in defining the equilibrium state. These equations reduce to the more special case previously derived when only nearest‐neighbor effects are considered.