High-Barrier Polyimide Containing Carbazole Moiety: Synthesis, Gas Barrier Properties, and Molecular Simulations

Abstract

A high-barrier polyimide (2,7-CPI) was synthesized through the polymerization of pyromellitic dianhydride (PMDA) and a novel diamine (2,7-CDA) containing carbazole moiety. The synthesized diamine and polyimide were fully characterized by elemental analyses, FTIR and NMR. The 2,7-CPI displays very attractive barrier performances, with oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) low to 0.14 cm3·m−2·day−1 and 0.05 g·m−2·day−1, respectively. Meanwhile, 2,7-CPI also exhibits exceptional thermal stability with a glass transition temperature (Tg) of 467 °C, 5% weight-loss temperature (Td5%) of 550 °C under N2 and coefficient of thermal expansion (CTE) of 3.4 ppm/K. The barrier performances of 2,7-CPI are compared with those of a structural analogue (2,7-CPPI) and a typical polyimide (Kapton). Their barrier performances with respect to microstructure were investigated by molecular simulations, wide angle X-ray diffraction (WAXD), and positron annihilation lifetime spectroscopy (PALS). The results show that 2,7-CPI possesses better coplanar structure and more number of intermolecular hydrogen bonds among the three PIs, which result in tight chain packing and thereby high crystallinity, low free volume, and decreased chains mobility. That is, the high crystallinity and low free volume of 2,7-CPI reduce the diffusion and solubility of gases. Meanwhile, the poor chains mobility further decreases the gases diffusion. The reduced diffusion and solubility of gases consequently promote the improvement of barrier properties for 2,7-CPI. The polyimide has a wide application prospect in the field of flexible electronic packaging industries.

Structure-Gas Barrier Property Relationship in a Novel Polyimide Containing Naphthalene and Amide Groups: Evaluation by Experiments and Simulations

“… a Units of (cm 3 (STP)·cm −3 ·cm Hg −1 ); b (10 −8 ·cm 2 ·s −1 ); c (10 −8 cm 3 (STP)·cm·cm −2 ·s −1 ·cm Hg −1 ); d Data comes from Ref. [ 56 ]. …”

“…Solubility coefficients, diffusion coefficients and permeability coefficients for H 2 O and O 2 in NAPPI and Kapton. Units of (cm 3 (STP)•cm −3 •cm Hg −1 ); b (10 −8 •cm 2 •s −1 ); c (10 −8 cm 3 (STP)•cm•cm −2 •s −1 •cm Hg −1 ); d Data comes from Ref [56]…”

Ultra‐highTgand ultra‐low coefficient of thermal expansion polyimide films based on hydrogen bond interaction

“…Unfortunately, the performance of commercial PI films, such as Kapton H® and Upilex S®, cannot meet the abovementioned requirement for flexible OLED substrates. Therefore, further improvement of T g and reduction of CTE have become hot research topics in the field of PI film materials 13–22 . Previous studies have shown that the intrinsic method, i.e., designing the molecular chain structure of PI, has the most obvious effect on the increase of T g and reduction of CTE 23–25 .…”

“…Therefore, further improvement of T g and reduction of CTE have become hot research topics in the field of PI film materials. [13][14][15][16][17][18][19][20][21][22] Previous studies have shown that the intrinsic method, i.e., designing the molecular chain structure of PI, has the most obvious effect on the increase of T g and reduction of CTE. [23][24][25] Yang et al prepared a series of PI films with pyridine and pyrimidine structures.…”

Synthesis of new copolyimides containing pyridine and morpholine groups for gas separation through molecular design and simulation

“…Morpholinyl, hexafluoroisopropyl (C[CF 3 ] 2 ), pyridine heterocyclic and fluorene “cardo” pendant non coplanar structures were introduced into the main chain of polyimide to investigate the influence of chemical structure under nitrogen atmosphere, physical properties and gas transport properties tested by various characterization methods. In addition, molecular dynamics simulation has emerged as an important theoretical tool to characterize the structural characteristics and gas permeation performances of polyimides at the atomic level, which is difficult to achieve by experimental means 34,40 . And a detailed molecular simulation study was carried out by Materials Studio 9 to comprehensively explore the relationship between chemical structures, free volume and gas transport properties of polymers.…”