Polyether urethane ureas

The most widely studied synthetic polymers for blood contact applications are polyether urethane ureas ( Biomer (Ethicon)). These materials have been used in artificial hearts, as coatings for lead wires in pacemakers, have been used and are being considered for blood vessel prostheses. The success of these materials is believed to be due to preferential adsorption of albumin rather than globulin or fibrinogen which promote a clotting response. However, these materials are hydrophobic and questions of long-term effectiveness are unresolved. Particularly, these materials may shed emboli or may be susceptible to surface calcification. Thus, it may be desirable to have synthetic polymers which are hydrophilic and better resemble blood vessels [475]. 

A Digilab 14B/D Fourier Transform infrared spectrometer was utilized to obtain l-cm 1 resolution spectra over the 4000-400 cm-1 region for polyether-urethane-urea films. The sample chamber was allowed to come to equilibrium with a continuous nitrogen purge prior to data collection of 1000 scans per sample. 

Urethane and urea Amide bands coupled with the N-H stretching bands have been studied by many investigators to explore the relationship between intermolecular and intramolecular interactions and morphologies of polyether-urethanes (16, 18-20, 23-32) and polyether-urethane-ureas (15,17,21,22,33-37). The N-H groups serve as proton donors in the interactions. The possible proton acceptors in polyether-urethanes initially were assumed to be only the urethane carbonyls or polyether oxygens (16, 19, 23-27). Under these assumptions, complete phase separation characterized... 

Novel polyether-urethane ureas—chain extension with tertiary alcohols [58]. 

Microporous polyether urethane-urea membranes were prepared from DMAc and methylethylketone solutions by electrostatic spinning method [77], The membranes were functionalized using isocyanate agents and further activated... 

The change of PU properties as a result of the plasticization process does not always correspond to the well-known views on the plasticization pattern, which were developed based on investigations of plasticized polymers having a uniform chemical stmcture of soft and hard phases (for example, PVC and esters of cellulose). In fact, the traditional views on plasticization of polymers are not suitable for explanation of maity effects observed by blending different plasticizers in polyurethane material. This behavior can be demonstrated on an example of segmented polyether-urethane-ureas. Their initial stmcture and properties (without plasticizers) are widely investigated. 

IPNs and gradient IPNs based on polyether-urethane-urea (PEUU) block copolymers and acrylamide, 2-hydroxyethyl methacrylate (HEMA), or N-vinyl-2-pyrrolidone. Intended for biomedical uses, such compositions created high-strength, water-absorbing hydrogel surfaces showing good blood compatibility. 

G. C. Berry and M. Dror, Modification of Polyurethanes by Interpenetrating Polymer Network Formation with Hydrogels, Am. Chem. Soc. Div. Org. Coat. Plast. Chem. Pap. 38(1), 465 (1978). Polyether-urethane-urea block copolymers with crosslinked HEMA, NVP, or acrylamide. IPNs and gradient IPNs for biomedical purposes. Strength, water swellability, and good blood compatibility. 

Figure 2.6 a-c provides a quantitive comparison of the infrared spectra of polyether urethane urea and Santowhite. The extract spectrum differed from that of the bulk of the polymer by the presence of bands from Santowhite in the 1630-1150 cm region and by the increased intensity and breadth of the 3324 cm (v (N-H)) and 1711 cm" v (C=0) hydrogen bonded bands of the urethane group. 

Table 2.8 gives the IR bands in the extract of polyether urethane urea that are attributed to the extracted Methacrol 2138 and Santowhite. Quantitative determination of Santowhite in the extracts was made with the band at 1386 cm, a 8(C-H) methylene band of Santowhite and a normalising band Vj,(CH2 - O) at 2797 cm which was assigned to the ether functionality of the PEUU. 

Table 2.8 New major FT-IR bands in polyether urethane urea extracts ...

Biomer Ethicon Polyether urethane urea (PTMO/ MDI/ED)... 

Different types of biostable PURs have been used in heart valve components, including polyether urethanes (PEUs), polyether urethane ureas (PEUUs), polycarbonate urethane (PCUs), polycarbonate urethane ureas (PCUUs), polycarbonate-based materials that contain polyhedral oligomeric silsequioxane nanoparticles (POSS) (Ghanbari et al., 2010 Kidane et al 2009b), and those that contain polysiloxane soft segments (Bezuidenhout et al 2015). 

Long-term fatigue and calcification testing was conducted on six flexible-leaflet prosthetic heart valves fabricated from a polyether-urethane-urea. Three valves exceeded 800 million cycles without failure, while three valves failed at 775,460 and 544 million cycles, respectively. Calcification was observed with and without associated failure in regions of high strain. Comparison was made with valves prepared from polyether-urethane. The results indicated that PU valves could achieve the durabilities required of an implantable prosthetic valve, equalling the fatigue fife of currently-available bioprosthetic valves. 14 refs. 

Figure 1. Transmission spectrum (3600-2600 cm" ) of Polyether-urethane-urea.

PEAK AREA RATIOS OF POLYETHER-URETHANE-UREA CARBON C(ls) ESCA SPECTRA... 

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