Assessing the Miscibility of Synthetic and Natural Polyols Through Hansen Solubility Parameters for Polyurethane Formulations

This study presents a comprehensive analysis of the solubility parameters and miscibility behavior of both synthetic and biobased polyols for potential applications in polyurethane (PU) formulations. Hansen Solubility Parameters (HSPs) were calculated using the Hoy and HVK group contribution methods for a wide range of polyols, including petrochemical polyethers, polyesters, and polycarbonates (e.g., PEG, PCL, PPC) and chemically modified renewable sources, such as Castor Oil, Epoxidized Soybean Oil (ESO), and modified Palm Oil. Principal Component Analysis (PCA) was employed to investigate the relationships among HSP components ( δ d , δ p , δ h ), density ( ρ ), and molecular weight ( M w ), revealing that PC1 and PC2 captured 50.32% and 33.46% of the total variance, respectively. The analysis differentiated synthetic polyols, which exhibited predictable trends with increasing molecular weight, from natural polyols, whose distribution appeared scattered due to their structural heterogeneity. Notably, PEG ( M w = 500 g/mol) showed chemical affinity to ESO and modified Cottonseed Oil (Hoy), while PPG and PCL ( M w = 4000 g/mol) aligned with less polar oils, such as Castor and modified Palm Oil (HVK). The study highlights the methodological differences between the Hoy and HVK approaches, with the former overestimating polarity and hydrogen bonding in natural polyols. The combination of PCA and solubility mapping enables a more accurate prediction of polyol compatibility, guiding the rational design of bio‐based and hybrid PU systems with optimized miscibility and processability.