Microporous segmented polyetherurethane vascular graft: I. Dependency of graft morphology and mechanical properties on compositions and fabrication conditions

Abstract

The influence of polyurethane compositions and fabrication conditions on the pore morphology and mechanical properties of microporous segmented polyetherurethane (SPEU) grafts, which were produced by the coagulation technique, were carefully investigated in this article. SPEU resins based on polytetramethylene oxide (PTMO) were synthesized by the solution polymerization method. Different types of coagulant were adapted to examine the feasibility of producing a microporous SPEU graft with good structural regularity. The experimental results indicate that a microporous SPEU graft with a uniform pore structure can be fabricated quite conveniently by using a proper concentration of water and ethanol mixed coagulant. Tensile tests demonstrated that the fabricated microporous SPEU grafts possess high mechanical strengths and satisfy the requirements as vessel replacements. The burst strength test also revealed that the SPEU graft can sustain extremely high internal pressure. Furthermore, a high compliant SPEU (high porosity) graft can be obtained by blending a proper amount of "soluble filler" (i.e., free PTMO polyol in this study) into the SPEU resin.

Prosthetic vascular grafts: Wrong models, wrong questions and no healing

“…Phase inversion alone, for example, led to micropores that were generally poorly interconnected and smaller than 15 mm [92,[96][97][98] therefore not allowing more than a shallow, superficial penetration by capillaries. Differences between various phase/temperature inversion techniques [99] allowed some degree of variability in this microporosity.…”

Development of Polyurethane-Based Sheets by Coagulation Method and Study of Mechanical and Cushion Properties for Therapeutic Footwear Applications

“…Dimethyl formamide was used to prepare PU solution and distilled water was used as nonsolvent or coagulant. According to reported procedures in literature [13][14][15] , the glass plate or tunnel containing layer of PU solution was immersed in coagulation medium and left for few hours to develop microporous PU membranes for biomedical applications.…”

Manufacture of small calibre quadruple lamina vascular bypass grafts using a novel automated extrusion-phase-inversion method and nanocomposite polymer

“…Ethanol's effect of reducing variation in pore size has been shown previously by Chen et al (1998), albeit at much higher concentration than here. Khorasani and Shorgashti, (2006b) have found a similar pore-size standardising effect with alcohols.…”

“…Many methods have been utilised to manufacture porous grafts for vascular bypass including salt leaching (Chen et al, 1998), electrospinning (Inoguchi et al, 2006), electrospraying with phase-inversion (Khorasani and Shorgashti, 2006a), excimer laser ablation (Doi et al, 1996), dip-coating and extrusion (Zdrhala, 1996). Porosity is desired to provide graft elasticity (Moroni et al, 2006); also enhancing adherence of endothelial cells to the graft lumen; as well as encouraging transmural support for successful cellular integration (Tsuchida et al, 1997).…”