03.09.2004: 
Professor Johan S Høye, Fysikk, NTNU :
Tilfeldig gang og termiske egenskaper til polymerer.

Phase diagrams for the coexistence of gas and liquid phases for polymer fluids as well as ionic fluids are tilted strongly towards low density as temperature increases toward the critical one. Motivated by a previous attempt to evaluate phase diagrams beyond the standard mean field approach for polymers we realized the need to have satisfactory knowledge about the structure factor or correlation function of the reference system polymer fluid besides its equation of state. The reference system have only repulsive interactions as the attractive interactions are removed. In view of this we here will consider a model of such a reference system where the polymers are made by monomers (single atoms) that are either squares (in the lattice case) or spheres (in the continuum case) that are linked together into polymer chains.

For this situation we have been able to develop a simplified approach utilizing arguments and results for simple (one-atomic) fluids. Then all monomers in polymers are considered equivalent being tied together in chains that form self-avoiding random walks. These random walks for single polymers as well as for interacting neighboring polymers are further approximated by use of methods that work for simple fluids. Here we will focus upon hard sphere monomers (single atoms) linked into polymers. In this case results like the equation of state and correlation function for the simple hard sphere fluid is generalized to polymer fluids consisting of hard sphere monomers.