Thermodynamic behavior of polymer

Summary The classical treatment of the physicochemical behavior of polymers is presented in such a way that the chapter will meet the requirements of a beginner in the study of polymeric systems in solution. This chapter is an introduction to the classical conformational and thermodynamic analysis of polymeric solutions where the different theories that describe these behaviors of polymers are analyzed. Owing to the importance of the basic knowledge of the solution properties of polymers, the description of the conformational and thermodynamic behavior of polymers is presented in a classical way. The basic concepts like theta condition, excluded volume, good and poor solvents, critical phenomena, concentration regime, cosolvent effect of polymers in binary solvents, preferential adsorption are analyzed in an intelligible way. The thermodynamic theory of association equilibria which is capable to describe quantitatively the preferential adsorption of polymers by polar binary solvents is also analyzed. 

Whatever the detailed interpretation of the thermodynamic behavior of polymer solutions, the term... 

Knowledge of solvent activities in polymer solutions is a necessity for a large number of industrial and laboratory processes. Such data are an essential tool for tmderstanding the thermodynamic behavior of polymer solutions, for studying their intermolecular interactions and for getting insights into their molecular nature. Besides, they are the necessary basis for any development of theoretical thermodynamic models. Scientists and engineers in academic and industrial research need such data. 

The thermodynamic properties of a polymer blend determine its performance. Many authors have focused on miscibility - this aspect has been extensively discussed in the literature (Olabisi et al. 1979 Sole 1982 Utracki 1989 Coleman et al. 1991 Paul and Bucknall 2000 Koningsveld et al. 2001), and few selected results, with the emphasis of what is not covered in details in the following chapters, are briefly mentioned here. The characterization methods of the thermodynamic behavior of polymer blends can be divided into groups ... 

The infortnation provided in this chapter can be divided into four parts 1. introduction, 2. thermodynamic theories of polymer blends, 3. characteristic thermodynamic parameters for polymer blends, and 4. experimental methods. The introduction presents the basic principles of the classical equilibrium thermodynamics, describes behavior of the single-component materials, and then focuses on the two-component systems solutions and polymer blends. The main focus of the second part is on the theories (and experimental parameters related to them) for the thermodynamic behavior of polymer blends. Several theoretical approaches are presented, starting with the classical Flory-Huggins lattice theory and, those evolving from it, solubility parameter and analog calorimetry approaches. Also, equation of state (EoS) types of theories were summarized. Finally, descriptions based on the atomistic considerations, in particular the polymer reference interaction site model (PRISM), were briefly outlined. 

While the measurement of osmotic pressure n and the calculation of the second virial coefficient A2 are relatively simple, their theoretical interpretations are rather comphcated. Throughout the past half century, many investigators have tried to set up a model and derive equations for n and A2. Because of the unsymmetrical nature with respect to the sizes of solute (macromolecule) and solvent (small molecule), polymer solutions involve unusually large intermolecular interactions. Furthermore, since n is directly related to pj, any theoretical knowledge learned from the osmotic pressure and the second virial coefficient contributes to the knowledge of the general thermodynamic behavior of polymer solutions. For this reason. Chapter 4 and 9 are closely related in macromolecular chemistry. 

Flory-Huggins model for polymer solutions, based on statistical thermodynamics, is often used for illustrating the behavior of polymer blends [6,7]. The expression for the free energy change... 

The thermodynamic behavior of the dilute polymer solution depends on three factors (1) the molecular weight, (2) the thermodynamic interaction parameters and ki, or ipi and 0, which characterize the segment-solvent interaction, and (3) the configuration, or size, of the... 

Kammer, H. W., Kressler, H. and Kummerioewe, C Phase Behavior of Polymer Blends - Effects of Thermodynamics and Rheology. Vol. 106, pp, 31-86. 

Why is it necessary to consider both the thermodynamic and kinetic behavior of polymer chains when describing the formation of structure in the polymer during cooling from the melt ... 

Let us now turn to the thermodynamic behavior of a polymer brush. Using the Alexander scaHng model, we can calculate the free energy per chain by putting the result for the optimal brush height, Eq. 13, into the free-energy expression, Eq. 12, and obtain... 

Maron, S. H., Nakajima, N. A theory of the thermodynamic behavior of non electrolyte solutions. II. Application to the system benzene-rubber. J. Polymer Sci. 40, 59-71... 

---