Nonbiodegradable polyurethane

Other synthetic polymers that have been utilised in the development of biomedical nanofibrous structures include the nonbiodegradable polyurethane (KhU et al., 2003 Kim et al., 2009 Verreck et al., 2003) and biodegradable polydioxanone (Kalfa et al., 2010). 

Ethylene vinyl acetate has also found major applications in drug delivery. These copolymers used in drug release normally contain 30-50 wt% of vinyl acetate. They have been commercialized by the Alza Corporation for the delivery of pilocarpine over a one-week period (Ocusert) and the delivery of progesterone for over one year in the form of an intrauterine device (Progestasert). Ethylene vinyl acetate has also been evaluated for the release of macromolecules such as proteins. The release of proteins form these polymers is by a porous diffusion and the pore structure can be used to control the rate of release (3). Similar nonbiodegradable polymers such as the polyurethanes, polyethylenes, polytetrafluoroethylene and poly(methyl methacrylate) have also been used to deliver a variety of different pharmaceutical agents usually as implants or removal devices. 

Biostability increases strongly by changing to polyether polyol based polyurethanes. Generally the polyethers are relatively non-toxic but nonbiodegradable products. 

Additive-based biodegradable materials usually incorporate a natural degradable polymer, such as com, rice, or potato starch, with a nonbiodegradable synthetic polymer, such as polyethylene, polypropylene, polystyrene, or polyurethane. It generally requires an accelerator additive to facilitate the breakdown of the polymer chain to the point at which it can be metabolized by microorganisms. 

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