Increased X-ray Visualization of Shape Memory Polymer Foams by Chemical Incorporation of Iodine Motifs.

David Kallmes,Kendal Ezell,Anthony Boyle,Duncan Maitland,Mary Browning Monroe,Yong-Hong Ding,Landon Nash,Ramanathan Kadirvel

doi:10.3390/polym9080381

David Kallmes, Kendal Ezell

Open Access

https://doi.org/10.3390/polym9080381

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Abstract

Shape memory polymers can be programmed into a secondary geometry and recovered to their primary geometry with the application of a controlled stimulus. Porous shape memory polymer foam scaffolds that respond to body temperature show particular promise for embolic medical applications. A limitation for the minimally invasive delivery of these materials is an inherent lack of X-ray contrast. In this work, a triiodobenzene containing a monomer was incorporated into a shape memory polymer foam material system to chemically impart X-ray visibility and increase material toughness. Composition and process changes enabled further control over material density and thermomechanical properties. The proposed material system demonstrates a wide range of tailorable functional properties for the design of embolic medical devices, including X-ray visibility, expansion rate, and porosity. Enhanced visualization of these materials can improve the acute performance of medical devices used to treat vascular malformations, and the material porosity provides a healing scaffold for durable occlusion.

Highlights

Shape memory polymers (SMPs) show significant promise for use in a variety of medical applications, including programmed surfaces for controlled cellular differentiation and alignment, microactuators, and implanted medical devices [1,2,3,4]
hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), butyl-2-ethyl propanediol (BEP), MPD, ATIPA, and HT were used as received from VWR Scientific (Radnor, PA, USA) and Sigma
Average gel fractions for the selected compositions ranged between 94.5–99.0%. These values are comparable to those reported in previous non-radiopaque SMP foam formulations [6]

Summary

Introduction

Shape memory polymers (SMPs) show significant promise for use in a variety of medical applications, including programmed surfaces for controlled cellular differentiation and alignment, microactuators, and implanted medical devices [1,2,3,4]. Thermally actuated ultralow density SMP polyurethanes synthesized as expanded, open porous foams have shown promise for endovascular occlusion of diseased peripheral blood vessels and intracranial aneurysms [5,6,7,8]. These vascular malformations contribute to complications such as severe chronic venous insufficiency, and subarachnoid hemorrhage [9,10]. SMP foams can improve upon the current standard of care for vascular occlusion, endovascular coils, by enhancing clotting and healing while maintaining minimally invasive delivery These programmable materials can be heated, crimped, and cooled into a metastable secondary geometry.

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