The present invention relates to a composition comprising a polymeric network having at least one unit of formula (I), (II), and/or (III); wherein the composition is obtained by contacting at least one compound A comprising at least two functions selected from the group of function of formula —X—C(═O)—CHR1-C(═O)—R2, —C(═O)—C≡C—R2; or —C(═O)—CR1═CR2—NR4R5; wherein at least 25% by weight of compounds A have a functionality ≤5, with % by weight relative to the total weight of compounds A; with at least one compound B comprising at least one —NH2, or —NH3+ groups; wherein X, R1, R2, R3, R4, R5, L1 and L2 have the same meaning as that defined in the claims. The present invention also relates to a compound comprising at least two units and at most 5 units of formula (I), (II), and/or (III), described hereinabove. The present invention also relates to processes for preparing the composition and the compounds, to material, articles, and polymers comprising or using the compositions and compounds, and the use thereof.