Designing Thermally Resistant Polyimide Oligomers: Insights from Molecular Dynamics Simulations

We
perform a systematic computational study for designing high-temperature
resistant Oligo-polyimides (Oligo-PIs). Their properties can be significantly
enhanced by substituting the diamine component. Oligo-PI Type A–
end-capped with 4-Phenylethynyl anhydride (4-PEPA) groups and comprising
of 11 repeat units of 1,3-Bis(4-aminophenoxy)benzene (TPE-R) and 10
repeat units of 3,4′-Biphthalic Anhydride (a-BPDA)) was chosen
for modification. We selected 4-PEPA and a-BPDA due to their efficacy
in forming thermally stable Oligo-PIs. Here, we developed a molecular
modification approach to substitute the Oligo-PI Type A TPE-R segment
with various commercially available polyimide (PI) monomers. This
method, integrated with high-fidelity molecular dynamics simulations,
allowed us to quantitatively predict the glass transition temperature
(Tg) and identify 27 Oligo-PI candidates
demonstrating structural integrity above 823 K, the conventional turbine
inlet gas temperature. Posteriori structural analysis revealed important
structural attributes such as side group, symmetry and configuration,
chain–chain interactions, and molecular symmetry, which are
crucial to their high Tg. This strategy
demonstrates a promising method for the tailored design of high-temperature
resistant materials, paving the way for advancements in gas turbine
materials.