Implantable material having at least one external surface grafted with a film comprising carboxylate and sulfonate functions wherein the film is simultaneously synthesized and grafted directly on said external surface by radical reaction of: - a bifunctional adhesion primer of Formula wherein R1 represents a group substituted by one carboxylate function and one sulfonate function, said group being selected from linear or branched alkyl, aryl, heteroaryl; said groups being optionally substituted by one or more substituent selected from alkyl, aryl, halogen or carbonyl; R2 represents an aryl or heteroaryl group substituted by at least one diazonium salt group and optionally further substituted by one or more substituent selected from alkyl, aryl or halogen; R3 is absent or represents or a linear or branched C1-C3 alkyl group, optionally substituted by one or more substituent selected from alkyl, aryl, heteroaryl, halogen or nitro; R4 represents a hydrogen atom or a group selected from alkyl, aryl, heteroaryl or alkylcarbonyl; or - an adhesion primer and a bifunctional polymerizable monomer of Formula wherein R a represents a group substituted by one carboxylate function and one sulfonate function, said group being selected from linear or branched alkyl, acyloxyalkyl, alkylcarbonyloxyalkyl, arylcarbonyloxyalkyl, alkylcarbonyloxyaryl, alkyloxycarbonylalkyl, aryloxycarbonylalkyl, alkyloxycarbonylaryl; optionally comprising heteroatoms in the main chain; said groups being optionally substituted by one or more substituent selected from alkyl, aryl, halogen or carbonyl groups; preferably, R a is an arylcarbonyloxyalkyl or an alkylcarbonyloxyalkyl group substituted by one carboxylate function and one sulfonate function; more preferably, R a is benzenecarbonyloxyethyl group or ethylcarbonyloxyethyl group substituted by one carboxylate function and one sulfonate function; R b represents H or methyl; X represents O or NH. - a bifunctional adhesion primer of Formula wherein R1 represents a group substituted by one carboxylate function and one sulfonate function, said group being selected from linear or branched alkyl, aryl, heteroaryl; said groups being optionally substituted by one or more substituent selected from alkyl, aryl, halogen or carbonyl; R2 represents an aryl or heteroaryl group substituted by at least one diazonium salt group and optionally further substituted by one or more substituent selected from alkyl, aryl or halogen; R3 is absent or represents or a linear or branched C1-C3 alkyl group, optionally substituted by one or more substituent selected from alkyl, aryl, heteroaryl, halogen or nitro; R4 represents a hydrogen atom or a group selected from alkyl, aryl, heteroaryl or alkylcarbonyl; or R1 represents a group substituted by one carboxylate function and one sulfonate function, said group being selected from linear or branched alkyl, aryl, heteroaryl; said groups being optionally substituted by one or more substituent selected from alkyl, aryl, halogen or carbonyl; R2 represents an aryl or heteroaryl group substituted by at least one diazonium salt group and optionally further substituted by one or more substituent selected from alkyl, aryl or halogen; R3 is absent or represents or a linear or branched C1-C3 alkyl group, optionally substituted by one or more substituent selected from alkyl, aryl, heteroaryl, halogen or nitro; R4 represents a hydrogen atom or a group selected from alkyl, aryl, heteroaryl or alkylcarbonyl; - an adhesion primer and a bifunctional polymerizable monomer of Formula wherein R a represents a group substituted by one carboxylate function and one sulfonate function, said group being selected from linear or branched alkyl, acyloxyalkyl, alkylcarbonyloxyalkyl, arylcarbonyloxyalkyl, alkylcarbonyloxyaryl, alkyloxycarbonylalkyl, aryloxycarbonylalkyl, alkyloxycarbonylaryl; optionally comprising heteroatoms in the main chain; said groups being optionally substituted by one or more substituent selected from alkyl, aryl, halogen or carbonyl groups; preferably, R a is an arylcarbonyloxyalkyl or an alkylcarbonyloxyalkyl group substituted by one carboxylate function and one sulfonate function; more preferably, R a is benzenecarbonyloxyethyl group or ethylcarbonyloxyethyl group substituted by one carboxylate function and one sulfonate function; R b represents H or methyl; X represents O or NH. R a represents a group substituted by one carboxylate function and one sulfonate function, said group being selected from linear or branched alkyl, acyloxyalkyl, alkylcarbonyloxyalkyl, arylcarbonyloxyalkyl, alkylcarbonyloxyaryl, alkyloxycarbonylalkyl, aryloxycarbonylalkyl, alkyloxycarbonylaryl; optionally comprising heteroatoms in the main chain; said groups being optionally substituted by one or more substituent selected from alkyl, aryl, halogen or carbonyl groups; preferably, R a is an arylcarbonyloxyalkyl or an alkylcarbonyloxyalkyl group substituted by one carboxylate function and one sulfonate function; more preferably, R a is benzenecarbonyloxyethyl group or ethylcarbonyloxyethyl group substituted by one carboxylate function and one sulfonate function; R b represents H or methyl; X represents O or NH.