Applications of biodegradable polyurethanes in 3D printing

Biodegradable polyesters are commonly incorporated as soft segments during the synthesis of biodegradable PUs. However, pyrohydrolysis of these biodegradable polyesters tend to occur at high temperature, which leads to a decrease in tensile 

Strength and release of acidic components [127]. Therefore, FDM and SLS are not suitable for 3D printing of biodegradable PUs. In recent years, most of the studies turned to the other methods to successfully print objects. Pfister et al. adopted adhesive ZPll (mixture of cellulose and starch) to 3D print biodegradable PU [128]. Unfortunately, the adhesive was water-soluble and the mechanical properties of the final products could not be maintained. To overcome this shortcoming, isocyanate was added to the adhesive ZPll to react with PU. While some success was achieved in increasing the water-resistance and tensile strength, the final products were shown to swell when implanted [128]. 

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