Synthesis, properties, and molecular simulations of high‐barrier polyimide containing carbazole moiety and amide group in the main chain. Issue 24 (19th November 2020)

• Record Type: Journal Article
• Authors: Liu, Yiwu; Tang, Ao; Tan, Jinghua; He, Pan; Chen, Chengliang; Wu, Ding; Li, Yuhui; Zhao, Xianqing; Zhang, Hailiang
• Is Part Of: Journal of polymer science. Volume 58:Issue 24(2020)
• Page Start: 3467
• Page End: 3479
• Publication Date: 2020-11-19
• Subjects: amide group -- barrier properties -- carbazole moiety -- molecular simulations -- polyimide; Polymers -- Periodicals; Polymerization -- Periodicals; Polymerization; Polymers; Periodicals; 547.7
• DOI: 10.1002/pol.20200545
• Languages: English
• ISSNs: 2642-4150

Abstract

Abstract: An intrinsic high‐barrier polyimide (2, 7‐CPAPPI) containing rigid planar carbazole moiety and amide group in main chain was prepared. The 2, 7‐CPAPPI shows very attractive barrier performances, possessing water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) low to 0.04 g m −2 day −1 and 0.11 cm 3 m −2 day −1, respectively. Meanwhile, 2, 7‐CPAPPI also displays exceptional thermal stability with a glass transition temperature ( T g ) of 552°C and coefficient of thermal expansion ( CTE ) of 15.48 ppm/K. The barrier performances of 2, 7‐CPAPPI are compared with those of a structural analog (2, 7‐CPPI, containing only carbazole moiety in the main chain) and a typical polyimide (Kapton). The structure–barrier performances relationship was investigated by molecular simulations, wide angle X‐ray diffraction (WAXD), and positron annihilation lifetime spectroscopy (PALS). The results show that 2, 7‐CPAPPI has more number of intermolecular hydrogen bonds among the three PIs, which leads to close chain packing and thereby high crystallinity, low free volume, and poor chains mobility. That is, the high crystallinity and low free volume of 2, 7‐CPAPPI decrease the diffusion and solubility of gases. Meanwhile, the poor chains mobility further reduces the gases diffusion. The decreased diffusion and solubility of gases consequently promote the improvement of barrier properties for 2, 7‐CPAPPI. Abstract : An intrinsic high‐barrier polyimide (2, 7‐CPAPPI) has been prepared through the polycondensation of pyromellitic dianhydride (PMDA) with a novel diamine (2, 7‐CPAPDA), which contains rigid planar carbazole moiety and amide group. With the introduction of carbazole moiety and amide group into the main chain of 2, 7‐CPAPPI, the crystallinity increases, and the free volume and chains mobility reduce. Those factors lead to the decrease of gases diffusion and solubility in the PI matrix and consequently improve the barrier properties.