Green Polymer Approach in the Production of Polyurethane Foams Using Chitosan and Citric Acid-Based Polyols

Polyurethane (PU) foams produced from fossil-based raw materials pose significant environmental and economic challenges. Consequently, sustainable and eco-friendly production methods have become a focal point for researchers in recent years. In this study, the potential use of chitosan as an alternative to fossil-based polyols was investigated in detail. Unlike methods described in the literature, it has been demonstrated that chitosan can be liquefied using citric acid, a low-cost and environmentally friendly component. MALDI-TOF MS and FTIR analyses, when evaluated together, confirmed that chitosan forms new bonds through an esterification reaction. The resulting biopolyol was used for PU foam synthesis by replacing 50% of the fossil-based polyether polyol. The chemical structure, morphology, and mechanical and thermal properties of the produced foams were evaluated using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), compressive strength, and thermogravimetric analysis (TGA), respectively. The results showed that the maximum decomposition temperature (75% mass loss) of PU foams produced using the chitosan-based biopolyol liquefied with citric acid increased from 390 to 429 °C. These findings demonstrate that the proposed method offers an alternative that is both environmentally friendly and economically beneficial. Furthermore, the fact that this approach to biopolyol production via the liquefaction of chitosan with citric acid is reported for the first time in the literature underscores the innovative nature of the study.