Interpretation of the Structure–Glass Transition Temperature Relationship for Organic Homopolymers with the Use of Increment, Random Forest, and Density Functional Theory Methods

The prediction of structural glass transition temperatures (Tg) of organic homopolymers is considered using the increment method and the quantitative structure–property relationship (QSPR) model based on the random forest algorithm. The increment method enables the calculation of the polymer glass transition temperature based on the monomer link structure: Tg = A/(B + C). The QSPR model demonstrates the accuracy of predicting Tg through parameters A, B, and C - R2 = 0.85. To interpret the physical meaning of A, B, and C parameters their correlation with quantum chemical descriptors is analyzed. A characterizes the Van der Waals volume of the repeating link of the organic homopolymer and weak intermolecular interactions. B shows a significant correlation with the electronic properties of monomer links of polymers, which indicates its relationship with both weak and strong intermolecular interactions. C characterizes the molecular packing coefficient and demonstrates the inverse dependence on the B parameter.