SPHERES: A MATLAB Tool for Teaching Solubility Parameter Calculations in Polymer Processing and Recycling

Solubility parameters are a fundamental tool in chemistry and chemical engineering for predicting and comparing the solubility of organic molecules and polymers. Group contribution (GC) theory simplifies these predictions by summing the cohesive energy contributions of functional groups within a molecule. However, as molecular complexity increases, manual calculations become cumbersome and error prone. To address this challenge, we developed Stefanis–Panayiotou and Hansen Evaluation and Reference Engine for Solubility (SPHERES), a user-friendly MATLAB application that calculates Hansen Solubility Parameters (HSPs) using both Hansen and Stefanis–Panayiotou GC frameworks. This program streamlines the calculations, enabling rapid and accurate HSP predictions for a wide range of molecular structures. We validated SPHERES against published data for common solvents and polymers. Its novel grouping feature allows users to combine moieties in custom subgroups for facile calculation of complex macromolecules, demonstrated with elastane, a copolymer widely used in textiles. While elastane’s complex molecular structure hinders recycling by traditional methods, SPHERES highlights potential selective dissolution pathways via efficient solvent selection. SPHERES was implemented in a graduate-level polymers course where students used it to understand the advantages of each GC framework, investigate polymer–solvent interactions, and apply solubility theory in practical scenarios. Students reported that SPHERES significantly reduced calculation time and minimized errors, enhancing both learning and problem-solving efficiency. SPHERES serves as a valuable resource for students, educators, and researchers, offering a practical, flexible approach to solubility parameter prediction.