Polymeric biomaterials polyurethanes

In dentistry, silicones are primarily used as dental-impression materials where chemical- and bioinertness are critical, and, thus, thoroughly evaluated.546 The development of a method for the detection of antibodies to silicones has been reviewed,547 as the search for novel silicone biomaterials continues. Thus, aromatic polyamide-silicone resins have been reviewed as a new class of biomaterials.548 In a short review, the comparison of silicones with their major competitor in biomaterials, polyurethanes, has been conducted.549 But silicones are also used in the modification of polyurethanes and other polymers via co-polymerization, formation of IPNs, blending, or functionalization by grafting, affecting both bulk and surface characteristics of the materials, as discussed in the recent reviews.550-552 A number of papers deal specifically with surface modification of silicones for medical applications, as described in a recent reference.555 The role of silicones in biodegradable polyurethane co-polymers,554 and in other hydrolytically degradable co-polymers,555 was recently studied. 

Szycher, M., A.A. Siciliano, and A.M. Reed, Polyurethane elastomers in medicine, in S, Dimitriu, Polymeric Biomaterials. New York Marcel Dekker, 1994, pp. 233-244. 

Archambault JG, Brash JL. Protein repellent polyurethane-urea surfaces by chemical grafting of hydroxyl-terminated poly(ethylene oxide) effects of protein size and charge. Colloids SutfB Biointerfaces 2004 33 111-20. http //dx.doi.Org/10.1016/j.colsurfb.2003.09.004. Desai NP, Hubbell JA. Solution technique to incorporate polyethylene oxide and other water-soluble polymers into surfaces of polymeric biomaterials. Biomaterials 1991 12 144-53. 

Among the many classes of polymeric materials now available for use as biomaterials, non-degradable, hydrophobic polymers are the most widely used. Silicone, polyethylene, polyurethanes, PMMA, and EVAc account for the majority of polymeric materials currently used in clinical applications. Consider, for example, the medical applications listed in Table A.l most of these applications require a polymer that does not change substantially during the period of use. This chapter describes some of the most commonly used non-degradable polymers that are used as biomaterials, with an emphasis on their use in drug delivery systems. 

K. Fujimoto, H. Tadokoro, Y. Ueda, Y. Ikada, Polyurethane surface modification by graft polymerization of acrylamide for reduced protein adsorption and platelet adhesion. Biomaterials 14 (6) (1993) 442-448. 

Polymeric materials that have been used in the cardiovascular system include polytetrafluorethy-lene, polyethylene terephthalate, polyurethane, polyvinyl chloride, etc. Textiles bas on polytetra-fluorethylene and polyethylene terephthalate are us extensively as fabrics for repair of vasculature and larger-vessel replacement (greater than 6 mm in diameter). Stent-grafts are hybrid stent grafts placed by catheter to treat aortic aneurysms nonsurgically and are fabricated of the same metallic alloys used in stents and textiles similar to those used in vascular grafts. Table 14.1 lists many of the biomaterials currently used in the cardiovascular system. 

It is known that the potential monomers or pol5uner building blocks should have at least one (in the case of addition polymerization) or two double bonds in their structure (in the case of condensation pol5nnerization) to get thermoplastic materials. Therefore, triglycerides should be modified of fimctionalized before pol5nnerization. Nevertheless, there are some examples of thermoplastic biomaterials obtained from naturally functionalized castor oil with homogeneous composition and acceptable polymerization yields. The main thermoplastic materials already synthesized from vegetable oils are thermoplastic polyurethanes (TPUs), polyamides (PA), thermoplastic polyesters, polyesteramides and polyanhydrides. 

Makal U, Wood L, Ohman DE, Wynne KJ. Polyurethane biocidal polymeric surface modifiers. Biomaterials 2006 27 1316-26. http //dx.doi.Org/10.1016/j.biomaterials.2005.08.038. 

Santerre, J. P., K. Woodhouse, G. Laroche, and R. S. Labow 2005. Understanding the biodegradation of polyurethanes From classical implants to tissue engineering materials. Biomaterials. 26 7457-70. Sawhney, A. S., C. P. Pathak, and J. A. Hubbell 1993. Bioerodible hydrogels based on photopolymerized poly(ethyleneglycol)-co-poly(alpha-hydroxyacid) diacrylate macromers.Macromo/ec /es. 26 581-87. Sciannamea, V., R. Jerome, and C. Detrembleur 2008. In-situ nitroxide-mediated radical polymerization (NMP) processes Their understanding and optimization. Chemical Reviews. 108 1104-26. 

Biomaterials [3] are defined as materials used within human bodies either as artificial organs, bone cements, dental cements, ligaments, pacemakers, or contact lenses. The human body consists of biological tissues (e.g., blood, cell, proteins, etc.) and they have the ability to reject materials which are incompatible either with the blood or with the tissues. For such applications, polymeric materials, which are derived from animals or plants, are natural candidates and some of these are cellulosics, chitin (or chitosan), dextran, agarose, and collagen. Among synthetic materials, polysiloxane, polyurethane, polymethyl methacry-... 

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