Following wetting, the ePTFE structure is transferred to a first solution consisting of an organic solvent, such as 100% acetonitrile, and a multifunctional crosslinking agent, such as a bis-variant of polyethylene glycol, preferable bis-benzotriazole carbonate(polyethylene glycol) dissolved in acetonitrile at a concentration between about 0.001 mg/mL and 500 mg/mL, preferably between about 0.2 mg