Determination of glass transition temperature of polyimides from atomistic molecular dynamics simulations and machine‐learning algorithms

Abstract

AbstractGlass transition temperature (Tg) plays an important role in controlling the mechanical and thermal properties of a polymer. Polyimides as an important category of engineering plastics have wide applications because of their superior heat resistance and mechanical strength. The capability of predicting Tg for a polyimide a priori is therefore highly desirable in order to expedite the design and discovery of new polyimide polymers with targeted properties and applications. Here we explore three different approaches to either compute Tg for a polyimide via all‐atom molecular dynamics simulations or predict Tg via a mathematical model generated by using machine‐learning algorithms to analyze existing data collected from the literature. Our simulations reveal that Tg can be determined from examining the diffusion coefficient of simple gas molecules in a polyimide as a function of temperature and the results are comparable to those derived from data on polymer density versus temperature and actually closer to the available experimental data. Furthermore, the predictive model of Tg derived with machine‐learning algorithms can be used to estimate Tg successfully within an uncertainty of about 20 degrees, even for polyimides yet to be synthesized experimentally.