Boosting the Prediction Accuracy of Glass Transition Temperature in Polyimides: A Hybrid Machine Learning Approach...

The glass transition temperature (T_g) of polyimides is a critical parameter determining their processability and application performance. Traditional experimental methods for measuring T_g are time-consuming and costly, while existing machine learning prediction models predominantly rely on manually defined molecular descriptors, which often fail to fully capture detailed molecular structural information, limiting their prediction accuracy and generalization capability. To address this, this study proposes a hybrid feature engineering strategy combining Morgan fingerprints and molecular descriptors to comprehensively represent the chemical structure of polyimides. Based on a dataset of 1257 polyimide samples from a public database, we systematically compared six feature selection methods and employed multiple mainstream machine learning algorithms for modeling. The results show that the CATB model performed best, achieving a coefficient of determination (R²) of 0.882 and a mean absolute error (MAE) of 17.34 °C on an independent test set, with fivefold cross-validation further confirming the model's robustness. SHAP interpretability analysis revealed the significant influence of key features such as the number of rotatable bonds, ether bonds, and ether-linked oxyethylene units on T_g, providing clear guidance for molecular design. External validation demonstrated the model's strong generalization ability. This study not only achieves high-precision and robust T_g prediction but also highlights the importance of hybrid feature strategies in polymer property modeling, offering a data-driven foundation for the rational design of polyimides.