Effects of π- π interactions on the rheological and heat-resistant behaviors of silicon-containing arylacetylene resins: A molecular dynamics simulation

H Li and WH Zhu, JOURNAL OF MOLECULAR LIQUIDS, 409, 125499 (2024).

DOI: 10.1016/j.molliq.2024.125499

Silicon-containing arylacetylene (PSA) resins are promising high- temperature resistant polymers. But their structure-property relationships at the atomic level are still unknown. In this study, the effects of pi-pi interactions on the rheological and heat-resistant behaviors of silicon-containing arylacetylene resins containing benzene unit (PSA-V), 2,7-diethynylnaphthalene unit (PSNP-V), and 2,7-diethynyl-9H-fluorene unit (PSA-VF) in main chains were explored using molecular dynamics. Compared to the PSA resin, the PSA-VF resin has stronger pi-pi stacking interactions, confirmed by interaction region indicator and energy decomposition analysis methods. When the resin has a higher fraction of aromatic ring, the mobility of the molecules decreases and so the diffusion capacity will be reduced. After analyzing the simulated trajectories for different resin systems, the face-to-face stacking between the resins was found. Compared with the PSA-V resin with relatively dispersed aggregate structure, the PSA-VF resin with larger-sized and more regular aggregate structure has higher viscosity and glass transition temperature due to stronger pi-pi interactions. These results provide a new perspective on the relationship between the pi-pi interactions and properties of the PSA resins.

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