Synthesis and characterization of biodegradable polyurethanes made from cholic acid and L-lysine diisocyanate ethyl ester

In this work, a series of biodegradable polyurethanes (PURs) based on cholic acid (CA) and L-lysine diisocyanate ethyl ester (L-LDI) that are renewable difunctional building blocks is synthesized by step-growth polymerization. Step-growth polymerizations between CA and L-LDI are conducted at different loading ratios by mole ([CA]/[L-LDI] (n/n) = 1:1; 1:2 and 1:4) to investigate the effect on wettability, thermal, and biodegradable properties of final PURs. The intermediates and resulting PURs are characterized by Fourier transform infrared spectroscopy (FT-IR), water contact angle measurements (WCA), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Moreover, biodegradability of obtained PURs is also investigated by conducting enzymatic degradation experiments. The experimental results reveal that PURs having higher L-LDI loading exhibit higher hydrophobic and thermal properties, while lower biodegradable characteristic compared to others. Thus, it is clear that the obtained PURs have great potential for several applications particularly in the fields of drug delivery and tissue engineering requiring biodegradable properties.