ABSTRACT
This chapter aims to establish a relationship between direct experimental measurements of the hydrogen bonded species present and the contribution of such interactions to the free energy of mixing. Equilibrium constants provide a direct link between stoichiometry, experimental infrared spectroscopic measurements and the free energy of mixing. The chapter provides mixtures of two different types of molecules that each self associate and, in principle, could then form "mixed" chains, each consisting of a distribution of various hydrogen bonded groups analogous to the various distributions found in (covalent) statistical copolymers. It focuses on a chemical repeat unit, or some arbitrary portion of the covalent chain defined so as to contain hydrogen bonding functional group. The chapter considers amorphous polymers at temperatures above their glass transitions. Flory argues that for the treatment of chemical equilibria between polymer species the most appropriate and least ambiguous reference state is that one in which the individual species are separate and oriented.
