Abstract: Disclosed is a polymer blend composition and shaped article, and a process of blending and making shaped articles of polymer blends in which the biocompatibility of various polymers is improved by blending with them a polymer including a zwitterionic group. The zwitterionic group is usually an ammonium phosphate ester, preferably a choline, zwitterionic group and the polymer containing it may be produced by the free radical polymerization of ethylenically unsaturated monomers including a monomer bearing the zwitterionic group. Blending of the two polymers may be achieved by dry blending particulate polymers or by mixing the polymers in liquid dispersion or solution followed by removal of the liquid medium. The fibrinogen absorption and/or platelet activation of polymers may be reduced to a value of less than 80% or even less than 60% of the base polymer by introducing amounts of more than 10% or more than 30% of the zwitterionic group containing polymer.

Abstract: A non-crosslinked polymer having pendant zwitterionic groups and pendant functional groups can be coated from a coating composition onto a surface having pendant coreactive functional groups and, after coating, may be cured so that covalent bonds are formed between the coreactive functional groups on the polymer and the surface. Alternatively the polymer can be crosslinked after coating, by formation of covalent intermolecular cross-links between coreactive pendant functional groups on the polymer. The zwitterionic pendant groups preferably have, as the anion, a phosphate ester group, and as the cation, a quaternary ammonium group. The polymer coating is stable and provides improved biocompatibility, especially haemocompatibility.

Abstract: A braided stent (1) for transluminal implantation in body lumens is self-expanding and has a radial expanded configuration in which the angle .alpha. between filaments is acute. Some or all of filaments (6,7) are welded together in pairs at each end (4,5) of the stent to provide beads (8), thereby strengthening the stent and assisting its deployment from a delivery device. The stent is preferably completely coated using a biocompatible polymeric coating, said polymer preferably having pendant phosphoryl choline groups. A method of making the stent by braiding and welding is described as well as a delivery device for deploying the device.

Abstract: The biocompatibility of various polymers is improved by blending with them a polymer including a zwitterionic group. The zwitterionic group is usually an ammonium phosphate ester zwitterionic group and the polymer containing it may be produced by the free radical polymerisation of ethylenically unsaturated monomers including a monomer bearing the zwitterionic group. Blending of the two polymers may be achieved by dry blending particulate polymers or by mixing the polymers in liquid dispersion or solution followed by removal of the liquid medium. The fibrinogen absorption and/or platelet activation of polymers may be reduced to a value of less than 80% or even less than 60% of the base polymer by introducing amounts of more than 10% or mare than 30% of the zwitterionic group containing polymer. Preferred blends are of copolymers of 2-(methacryloyloxyethyl)-2'-(trimethylammonium)ethyl phosphate inner salt with higher alkyl (meth) acrylate, blended with olefin polymers and/or with rubber latices.