Morphology and surface properties of high strength siloxane poly(urethane‐urea)s developed for heart valve application

Abstract

A series of siloxane poly(urethane-urea) (SiPUU) were developed by incorporating a macrodiol linked with a diisocyanate to enhance mixing of hard and soft segments (SS). The effect of this modification on morphology, surface properties, surface elemental composition, and creep resistance was investigated. The linked macrodiol was prepared by reacting α,ω-bis(6-hydroxyethoxypropyl) poly(dimethylsiloxane)(PDMS) or poly(hexamethylene oxide) (PHMO) with either 4,4'-methylenediphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), or isophorone diisocyanate (IPDI). SiPUU with PHMO-MDI-PHMO and PHMO-IPDI-PHMO linked macrodiols showed enhanced creep resistance and recovery when compared with a commercial biostable polyurethane, Elast-Eon™ 2A. Small and wide-angle X-ray scattering data were consistent with significant increase of hydrogen bonding between hard and SS with linked-macrodiols, which improved SiPUU's tensile stress and tear strengths. These SiPUU were hydrophobic with contact angle higher than 101° and they had low water uptake (0.7%·w/w of dry mass). They also had much higher siloxane concentration on the surface compared to that in the bulk. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018.

Novel Polymeric Valve for Transcatheter Aortic Valve Replacement Applications: In Vitro Hemodynamic Study

“…26,38 The Triskele (UCL TAV™, University College London, London, UK) TAVR valve utilizes urethane (POSS-PCU) leaflets and skirt, demonstrated in vitro testing comparable hydrodynamic performance to other, clinically-used, tissue TAVR valves. 27 Foldax Inc. (Salt Lake City, UT, USA) utilizes an elastomer in their prosthetic heart valve products, 10,11 which include aortic and mitral surgical valves, and a transcatheter valve. Strait Access Technologies (SAT, Cape Town, South Africa) develops a heparinized polyurethane TAVR valve for rheumatic heart disease (RHD) patients and recently passed over 600 M cycles in vitro accelerated durability testing.…”

Synthesis, characterization, and aging resistance of the polyurethane dimethacrylate layer for dental restorations

“…The main component of FL and SB2 adhesives is methacrylate‐based monomers, such as bisphenyl A glycidyl methacrylate (Bis‐GMA) and HEMA. Diffusion of Bis‐GMA and HEMA is influenced by the rigidity of the two central aromatic rings and the high viscosity of Bis‐GMA, mainly because of the two hydroxyl groups, which form strong hydrogen interactions . Once polymerized, the increased viscosity continuously impacts the movement of monomers and chain growth until the reaction terminates.…”

In vitro oxidative stability of high strength siloxane poly(urethane‐urea) elastomers based on linked‐macrodiol

“…However, the unchanged intensity of the urethane amide peak, and absence of a peak at 1650 cm −1 for free aromatic amine indicate that the hard segment in E2A as well as in SiPUU‐1 and SiPUU‐2 is not degraded. The presence of higher amount of hydrophobic PDMS in these materials may be preventing the hydrolytic degradation of hard segment …”

“…H‐bonding in the hard segment makes them more resistant to biodegradation . Therefore SiPUU‐1 and SiPUU‐2 can be expected to be more biostable compared with E2A because of additional hydrogen bonding in the hard segment associated with urea linkages . These two materials showed increased peak intensity of urea carbonyl absorption at 1635 cm −1 due to additional urea in the hard segment, unlike in E2A.…”

“…The polarity introduced into the soft segment reinforced the interaction between siloxane based soft segment and the hard segment resulting in improved mechanical properties. Furthermore, these materials showed higher creep resistance and recovery compared with E2A . The chemical modification introduced in the soft segment could influence the biostability.…”