Catheter Having a Coextruded Fluoropolymer Layer

A catheter shaft comprising:

• an elongate tubular member having a first end, a second end and a tubular wall extending between the first end and the second end;
• the elongate tubular member including:
• i) an inner polymeric layer formed of a polymer generally not bondable to fluoropolymers;
• and
• ii) an outer fluoropolymer layer bonded to the inner polymeric layer;
• wherein the outer fluoropolymer layer includes a functionalized polyvinylidene fluoride which has a bonding affinity to the inner polymeric layer;
• wherein the functionalized polyvinylidene fluoride includes reactive functional groups chemically bonded to a polymer chain of a polyvinylidene fluoride.

A method of forming a catheter shaft, the method comprising:

• extruding a first polymer in a molten state onto a mandrel, forming a first molten layer of the first polymer;
• extruding a second polymer in a molten state over the first molten layer of the first polymer, forming a second molten layer of the second polymer over the first molten layer of the first polymer;
• passing the first molten layer of the first polymer and the second molten layer of the second polymer through an extrusion die while the first molten layer and the second molten layer remain in their molten state;
• and
• allowing the first molten layer of the first polymer and the second molten layer of the second polymer to cool, wherein a bilayer polymer tube is formed having an outer layer formed of the first polymer bonded to an inner layer formed of the second polymer without any intervening layer positioned between the inner layer and the outer layer of the bilayer polymeric tube;
• wherein one of the first polymer and the second polymer is a functionalized polyvinylidene fluoride, while the other of the first polymer and the second polymer is a polymer generally not compatible with polyvinylidene fluoride.