FTIR spectroscopy offers advantages such as rapid data acquisition, high sensitivity, quantitative analysis capabilities, broad applicability to various sample types, and its utility in identifying functional groups and performing structural analysis. Therefore, FTIR spectroscopy was used to determine chemical structure the synthesized macromonomer and PEGylated fibrinogen. In the case of macromonomer, the FT-IR measurements confirmed that the chemical structure of the obtained material was consistent with the assumed reaction mechanism and with our recent work .