Telechelic polyolefin of formula(I) and its derivatives: CH2═CH—(CH2)p-A-Z  (I) wherein: A represents a (co)polymer comprising at least 95 mol % of (CH2—CH2) units; Z is selected from the group comprising halogens, thiols and their derivatives, azides, amines, alcohols, the carboxylic acid function, isocyanates, silanes, phosphorous derivatives, dithioesters, dithiocarbamates, dithiocarbonates, trithiocarbonates, alkoxyamines, the vinyl function, dienes, and the group -A-(CH2)p—CH═CH2; p is a whole number between 1 and 20, most advantageously between 6 and 9.