Purely attractive or repulsive chains existence of continuous models

1 Purely attractive or repulsive chains existence of continuous models 

It would be very difficult to analyse the interaction between polymer and solvent in detail, at a given temperature. Actually, this would also be useless, if we want only to predict the properties of solutions of long polymers. In fact, the 

The arrows show the limits of the 0 domain (tricritical domain). 

Let us examine which model can be chosen to represent a chain the links of which are partially attractive. First, let us consider chains with N links (N 1) on a d-dimensional square lattice, starting from an origin O. We assume that the weight associated with such a chain is 

JV g 1 has a Kuhnian behaviour (chains in good solvent). What happens if u 0  

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