The present invention relates to the field of perfumery. More particularly, it concerns co-polymers, derived from a maleic anhydride derivative and a ethylenic derivative, comprising at least one &bgr-oxy or &bgr-thio carbonyl moiety capable of liberating an active molecule such as, for example, an &alpha,&bgr-unsaturated ketone, aldehyde or carboxylic ester. The present invention concerns also the use of polymers or co-polymers in perfumery as well as the perfuming compositions or perfumed articles comprising the inventions compounds.
