Environmental stress cracking performance of polyether and PDMS‐based polyurethanes in an in vitro oxidation model

Abstract

Environmental stress cracking (ESC) was replicated in vitro on Optim™ (OPT) insulation, a polydimethylsiloxane-based polyurethane utilized clinically in cardiac leads, using a Zhao-type oxidation model. OPT performance was compared to that of two industry standard polyether urethanes: Pellethane 80A (P80A), and Pellethane 55D (P55D). Clinically relevant specimen configurations and strain states were utilized: low-voltage cardiac lead segments were held in a U-shape by placing them inside of vials. To study whether aging conditions impacted ESC formation, half of the samples were subjected to a pretreatment in human plasma for 7 days at 37°C; all samples were then aged in oxidative solutions containing 0.9% NaCl, 20% H O , and either 0 or 0.1M CoCl , with or without glass wool for 72 days at 37°C. Visual and SEM inspection revealed significant surface cracking consistent with ESC on all P80A and P55D samples. Sixteen of twenty P80A and 10/20 P55D samples also exhibited breaches. Seven of 20 OPT samples exhibited shallow surface cracking consistent with ESC. ATR-FTIR confirmed surface changes consistent with oxidation for all materials. The number average molecular weight decreased an average of 31% for OPT, 86% for P80A, and 56% for P55D samples. OPT outperformed P80A and P55D in this Zhao-type in vitro ESC model. An aging solution of 0.9% NaCl, 20% H O , and 0.1M CoCl , with glass wool provided the best combination of ESC replication and ease of use. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1544-1558, 2017.

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

“…In our study, the H‐bonding index of PEU and PCU‐Si decreased with increasing treatment time while that of E2A, SiPUU‐1, and SiPUU‐2 remained unchanged. Gallagher et al and Hernandez et al have reported a similar observation for polyether and polycarbonate polyurethanes …”

“…The presence of a minor peak at 1173 cm −1 due to branched ether indicates that the soft segments of E2A, SiPUU‐1 and SiPUU‐2 are likely to undergo degradation by the breakdown of the ether linkages. Previous studies on E2A showed similar resistant to soft segment degradation . SEM and ATR‐FTIR results showed that the incorporation of a urethane linker into the soft segment of SiPUU‐1 and SiPUU‐2 has not affected their oxidative stability and is comparable with E2A.…”

“…Zhao et al introduced two in vitro models, glass wool method and human plasma pretreatment method to mimic the in vivo oxidative environment which enabled to predict long‐term biostability . Recently Gallagher et al confirmed the Zhao's glass wool method as the best test procedure to reproduce in vivo ESC …”

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

“…Elast‐Eon™ 2A (denoted here as E2A) was received from Abbott, MN (formerly St Jude Medical, St Paul, MN). E2A is a polyurethane in which the SS is formed from a mixture of PDMS and PHMO (80:20) and the hard segment from MDI and BDO . Table shows molecular weights and dispersity of the synthesized SiPUU, the SS composition and relevant abbreviation of SiPUU referred to this discussion.…”

Inelastic deformation of highly aligned dry-spun thermoplastic polyurethane elastomer microfibres

“…The chemical structure of the polyurethane is shown in the Figure 1. Soft domains of the polyurethane are comprised of the polyester [52] and polyether [53] groups, whereas the hard domains are comprised of the methylene diphenyl diisocyanate (MDI) [52] groups. N,N-Dimethylformamide (DMF) and Tetrahydrofuran (THF) with purity more than 99 % were used as solvents to dissolve the MDI-polyester/polyether polyurethane pellets.…”