Polyurethane having an antithrombogenic coating

A method of producing an antithrombogenic polyurethane (PUR) comprising the following steps:

• a) activation of an antithrombogenic coating on a surface comprised of polyurethane PUR, wherein activation is performed by use of a plasma, and wherein i) the plasma is a carbon dioxide plasma, or ii) the plasma is modified by addition of carbon dioxide,
• b) a first coupling, wherein a polyethyleneimine (PEI) is coupled to the PUR surface, and
• c) a second coupling, wherein at least one antithrombogenic substance is coupled to the PEI,
• to produce an antithrombogenic PUR surface, the antithrombogenic surface comprised of at least one antithrombogenic substance covalently bound to a surface of the PUR via at least two bonds, wherein a first of said bonds is an amide bond between the surface of the PUR and a PEI and a second of said bonds is between the PEI and the antithrombogenic substance.