Liquid Equilibrium States

Abstract

After having considered the structural behavior of single chains we turn now to the collective properties of polymers in bulk phases and discuss in this chapter liquid states of order. Liquid polymers are in thermal equilibrium, so that statistical thermodynamics can be applied. At first view one might think that theoretical analysis presents a formidable problem since each polymer may interact with many other chains. This multitude of interactions of course can create a complex situation, however, cases also exist, where conditions allow for a facilitated treatment. Important representatives for simpler behavior are melts and liquid polymer mixtures, and the basic reason is easy to see: As here each monomer encounters, on average, the same surroundings, the chain as a whole experiences in summary a ‘mean field’, thus fulfilling the requirements for an application of a well established theoretical scheme, the ‘mean-field treatment’. We shall deal with this approach in the second part of this chapter, when discussing the properties of polymer mixtures.