Comparison of Homo-Polyimide Films Derived from Two Isomeric Bis-Benzimidazole Diamines

Authors:
Open Access
Publisher website
Google Scholar
Abstract
Heteroaromatic polyimides (PIs) containing benzimidazole have attracted tremendous attention due to their positive impact on the properties of PIs. Some research on PIs containing 4,4′-[5,5′-bi-1H-benzimidazole]-2,2′-diylbis-benzenamine (4-AB) has been reported. However, reports are lacking on homo-polyimides (homo-PIs) containing 3,3′-[5,5′-bi-1H-benzimidazole]-2,2′-diylbis-benzenamine (3-AB), which is one of the isomers of 4-AB. In this paper, the influence of amino groups’ positions on the performance of homo-PIs was investigated. It was found that the net charge of the amine N group in 4-AB was lower than that of 3-AB, resulting in higher reactivity of 4-AB. Consequently, PIs containing 4-AB displayed better mechanical performance. Molecular simulation confirmed that 3-AB and its corresponding PI chain exhibited distorted conformation, leading to the PI films containing 3-AB having a lighter color. In addition, the 3-AB structure was calculated to have higher rotational energy compared to 4-AB, resulting in a higher glass transition temperature (Tg) in PIs prepared from 3-AB. On the other hand, PIs containing 4-AB exhibited a higher level of molecular linearity, leading to a lower coefficient of thermal expansion (CTE) compared to PIs prepared from 3-AB. Furthermore, all PIs showed higher thermal stability with a 5% weight loss temperature above 530 °C and Tg higher than 400 °C.
Funding Information
  • Natural Science Foundation of Shandong Province (ZR2021QB194, 52003196, 52233016, 51733007, KJRC2020006)
  • National Natural Science Foundation of China (ZR2021QB194, 52003196, 52233016, 51733007, KJRC2020006)
  • Doctoral Fund of Weifang University of Science and Technology (ZR2021QB194, 52003196, 52233016, 51733007, KJRC2020006)

This publication has 54 references indexed in Scilit: