The synthesis of polymer networks by controlled free radical polymerization has been investigated in the case of atom transfer radical. polymerization (ATRP). The synthesis of a difunctional initiator, bis(2-bromopropionyloxy) ethane (BBPE) makes possible the preparation of difunctional polymer precursors that can be used to prepare polymer networks by an end-linking process. The gels thus formed have been characterized by the determination of the fraction of polymer precursors unlinked to the crosslinks and by the determination of the swelling equilibrium of the gels in xylene.