  We propose a field-theoretical approach to a polymer system immersed in an
ideal mixture of clustering centers. The system contains several species of
these clustering centers with different functionality, each of which connects a
fixed number segments of the chain to each other. The field-theory is solved
using the saddle point approximation and evaluated for dense polymer melts
using the Random Phase Approximation. We find a short-ranged effective
inter-segment interaction with strength dependent on the average segment
density and discuss the structure factor within this approximation. We also
determine the fractions of linkers of the different functionalities.
