Membrane preparation expanded film membranes

Fig. 5. (a) Preparation method and (b) scanning electron micrograph of a typical expanded polypropylene film membrane, ia this case Celgard. 

As noted in Section 12.5.1, a family of polyaxial copolyesters described in Chapter 2 can be used to prepare two or more of the critical components of a femoral sealing device. Other compliant members of this family of polymers, which can be converted to compliant, stretchable membranes and strong, stretchable monofilament fibers, can be used to construct a mantle or cover for metallic endovascular stents. Thus, a composite of thin film, reinforced with a monofilament in cross-coiled configuration, can be assembled into a highly compliant, expandable, tubular mantle or sleeve. This can be placed tightly as a cover outside an expandable metallic or polymeric stent so that under concentric irreversible expansion at the desired site of... 

The polyion complex technique [15] was proposed as a convenient preparative method to immobilize water-soluble, bilayer-forming amphiphiles and polymers as composite thin films. A water-insoluble polyion complex is precipitated when the aqueous solution of the charged bilayer membrane is mixed with a water solution of the countercharged polyelectrolyte. The polyion complex mono-layer also can be formed in situ when the charged amphiphiles are directly spread on the surface of the aqueous polyelectrolyte solution. The principle of the polyion complex LB technique has been expanded into a general and simple alternative deposition method of charged polymers by Decher [16] (this volume chapter 12). 

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