Novel highly flexible copolymers bearing dienic or dienophilic moieties were prepared by either free radical copolymerization of hexyl acrylate and 2-furfuryl methacrylate or the chemical modification of siloxane copolymers with pendant primary propylamino functions. In addition, maleimides were synthesized from oligoether bis(amine)s and from the amino pendant groups of the polysiloxane. Diels-Alder reactions between these copolymers and difunctional complementary coupling agents produced cross-linked elastomers in high yields. The thermal reversible character of these networks was confirmed by applying retro-Diels-Alder reactions in the presence of appropriate trapping reagents which restored the initial linear polymers quantitatively.