Monomers and oligomers used in degradable polyurethanes

The monomers and oligomers used in the design of degradable PUs are summarized in Table 3.2. 

Block copolymeric/degradable PUs provide significant advantages over classical degradable polyesters because of their chemical diversity, which yields uniquely compatible materials with respect to the biological responses to implants, and provides the field with a versatile range of physical properties when compared to other classes of biomaterials. Their attributes will enable many practical solutions to medical devices that are currently not afforded by other contemporary biomaterials. Hopefully this review will inspire the exploration of new PU chemistries with respect to biological interactions. 

Yields putrescine following degradation, a polyamine essential for cell growth 

Diamines released on degradation are toxic to human liver and kidney, though less toxic than aromatic diamines from MDI or TDI 

Hydrolytic, esterolytic, and oxidative degradation Nontoxic degradation by-product (lysine) 

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