Degradable Bioelastomers: Synthesis and Biodegradation
Degradable bioelastomers are an important branch of degradable polymeric biomaterials, which mainly present four characters different from other polymeric biomaterials: stable crosslinked structures of three-dimensional networks similar to the natural collagen and elastin endowing elasticity with the natural extracellular matrix, certain flexibility and elasticity which can provide mechanical stimulation for tissue engineering constructs, appropriate mechanical properties especially matching with soft tissues and organs of bodies, and easily adjustable and designable biodegradation by controlling their crosslinking density. They can be prepared by varied synthesis methods such as polycondensition, ring-opening polymerization, thermally and photo initiated radical polymerization, which are chiefly applied in soft tissue engineering and controlled drug delivery. The biodegradation is a very important property of degradable bioelastomers, which is often discussed in the studies. The degradation rates of degradable bioelastomers are usually able to be tuned in a wide range by controlling their molecular structure, segment length and composition, molar ratio of monomers, reaction temperature, polymerization time, curing method and degradation condition, etc. In this chapter, degradable bioelastomers are classified as eight types of degradable segmented polyurethane bioelastomers, poly(ε-caprolactone) related bioelastomers, polylactide related bioelastomers, polycarbonate related bioelastomers, poly(glycerol sebacate) bioelastomer and its derivatives, citric acid related polyester bioelastomers, poly(ether ester) bioelastomers and poly(ester amide) bioelastomers, and their synthesis and biodegradation are specially introduced accompanying with many typical examples. Moreover, other several novel degradable bioelastomers are also mentioned. In the future, degradable bioelastomers are sure to play a more important role in degradable polymeric biomaterials.