Effect of polyol molecular weight on the physical properties and haemocompatibility of polyurethanes containing polyethylene oxide macroglycols

Modification of polyurethaneurea with PEG and YIGSR peptide to enhance endothelialization without platelet adhesion

“…11,[15][16][17] In this study, 4600 mol/g PEG was incorporated at a 15% molar ratio as a soft segment. As shown above, this amount was enough to form a PEG rich phase on the surface, preventing cell attachment.…”

“…8,10 To improve biocompatibility, various efforts have been made to introduce PEG into biomaterials by grafting, 9,11-13 physical blending, 14 covalent attachment to the surface mediated by proteins, 15,16 and synthesis of copolymers. 17 Covalent incorporation of PEG into polyurethaneureas as at least a portion of the soft segment is desirable for long-term stability and three-dimensional fabrication of a nonthrombogenic biomaterial.…”

Platelet adhesion to polyurethane blended with polytetramethylene oxide

“…Various hypotheses have been advanced to reconcile these conflicting observations on the role of PTMO in platelet adherence. Earlier interpretations of polyurethane blood compatibility experiments (reviewed in Lelah and Cooper, 1986) tended to focus on the chemical composition of the surface, but more recent interpretations have given more emphasis to the surface arrangement, degree of phase separation, and organization of the hard and soft segments (Grasel et al, 1987a,b;Kajiyama and Takahara, 1991;Silver et al, 1994).…”

“…If the hard segment were much less mobile than the blended PTMO, then the PTMO might be favored over the hard segment in water, even though PTMO is considered to be more hydrophobic than the hard segment (Takahara et al, 1985a,b). Indeed, the hard segment in MDI-PTMO-BD polyurethanes can show little mobility: freeze-dried polyurethane samples examined with an XPS instrument equipped with a cold stage showed no enrichment of the hard segment in water as compared to in vacuo conditions (Silver et al, 1994).…”

“…These materials generally have excellent strength, moldability, and elasticity, but can activate platelets, potentially causing the formation of thrombi that can restrict blood flow or cause emboli downstream. A number of approaches have been explored to decrease polyurethane thrombogenicity, such as grafting octadecyl groups to its surface so that it preferentially adsorbs albumin (Eberhart et al, 1987;Grasel et al, 1987b;Hanson et al, 1980), or incorporating a hydrophilic component such as polyethylene glycol into the soft segment (Okkema et al, 1989;Silver et al, 1994). Some of these various approaches show promise, but have not yet solved the problem of thrombus formation on polyurethanes.…”