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The article presents a new concept for vascular endoprothesis (stent). Almost all commercially available stents are made of metallic materials. A common after effect of stent implantation is restenosis. Several studies on metal stents coated with drug show, that the use of a drug delivery system may reduce restenosis. The purpose of this work is to develop a new stent for the drug delivery application. The shape memory properties of thermoplastic polyurethane allow to design a new fully polymeric self-expandable stent. The possibility to use the stent as a drug delivery system is described.

A main-chain, polydomain, smectic liquid crystalline elastomer (LCE) was prepared by reacting the LC epoxy monomer, diglycidyl ether of 4,4‘-dihydroxy-α-methylstilbene, with the aliphatic diacid, sebacic acid. When deformed in uniaxial tension, a “polydomain-to-monodomain” transition took place leading to bulk, macroscopic orientation. With this process was associated a plateau in the nominal stress-versus-strain curve and a dramatic change in optical properties from opaque to translucent. Polarized optical microscopy showed that the transition took place by an elongation of the LC domains and a rotation of the local director orientations along the stress axis. The strain and orientation of the deformed samples were retained upon unloading, even after annealing above T g for extended periods. Upon heating, the oriented LCEs disordered at the same temperature as the undeformed polydomains and “remembered” their original polydomain microstructure and sample dimensions when subsequently cooled from the isotropic state.

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