Impact of Backbone Amide Substitution at the Meta- and Para-Positions on the Gas Barrier Properties of Polyimide

Qian Wen; Ao Tang; Chengliang Chen; Yiwu Liu; Chunguang Xiao; Jinghua Tan; Duxin Li

doi:10.3390/ma14092097

Materials (Apr 2021)

Impact of Backbone Amide Substitution at the Meta- and Para-Positions on the Gas Barrier Properties of Polyimide

Qian Wen,
Ao Tang,
Chengliang Chen,
Yiwu Liu,
Chunguang Xiao,
Jinghua Tan,
Duxin Li

Affiliations

Qian Wen: State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
Ao Tang: Key Laboratory of Advanced Packaging Materials and Technology of Hunan Province, National and Local Joint Engineering Center of Advanced Packaging Materials R & D Technology, School of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007, China
Chengliang Chen: Key Laboratory of Advanced Packaging Materials and Technology of Hunan Province, National and Local Joint Engineering Center of Advanced Packaging Materials R & D Technology, School of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007, China
Yiwu Liu: Key Laboratory of Advanced Packaging Materials and Technology of Hunan Province, National and Local Joint Engineering Center of Advanced Packaging Materials R & D Technology, School of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007, China
Chunguang Xiao: State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
Jinghua Tan: Key Laboratory of Advanced Packaging Materials and Technology of Hunan Province, National and Local Joint Engineering Center of Advanced Packaging Materials R & D Technology, School of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007, China
Duxin Li: State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China

DOI: https://doi.org/10.3390/ma14092097
Journal volume & issue: Vol. 14, no. 9
p. 2097

Abstract

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This study designed and synthesised a meta-amide-substituted dianiline monomer (m-DABA) as a stereoisomer of DABA, a previously investigated para-amide-substituted dianiline monomer. This new monomer was polymerised with pyromellitic dianhydride (PMDA) to prepare a polyimide film (m-DABPI) in a process similar to that employed in a previous study. The relationship between the substitution positions on the monomer and the gas barrier properties of the polyimide film was investigated via molecular simulation, wide-angle X-ray diffraction (WXRD), and positron annihilation lifetime spectroscopy (PALS) to gain deeper insights into the gas barrier mechanism. The results showed that compared with the para-substituted DABPI, the m-DABPI exhibited better gas barrier properties, with a water vapour transmission rate (WVTR) and an oxygen transmission rate (OTR) as low as 2.8 g·m−2·d−1 and 3.3 cm3·m−2·d−1, respectively. This was because the meta-linked polyimide molecular chains were more tightly packed, leading to a smaller free volume and lower molecular chain mobility. These properties are not conducive to the permeation of small molecules into the film; thus, the gas barrier properties were improved. The findings have significant implications for the structural design of high-barrier materials and could promote the development of flexible display technology.

Published in Materials

ISSN: 1996-1944 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering; Technology: Engineering (General). Civil engineering (General); Science: Natural history (General): Microscopy; Science: Physics: Descriptive and experimental mechanics
Website: http://www.mdpi.com/journal/materials/

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