Transparent Polyimide Nanocomposite for Flexible Display Substrates

A.R. Lim, J-H Chang
Kumoh National Institute of Technology,
Korea

Keywords: polyimide, nanocomposite, organoclay

Summary:

Recently, PI has been applied as an integrated material for semiconductor materials such as liquid crystal display (LCD) and plasma display panel (PDP) because of its low weight and its ability to improve electronic products. In addition, PI, which is lightweight and flexible, has been extensively studied for use in flexible plastic display substrates to overcome disadvantages such as heavy weight and tendency of shattering of glass substrates used in the field [1,2]. Among various layered inorganic materials used as nanofillers, clay has a layered structure with ionic bonds and Van der Waals forces acting between the layers. Clay has platelets with a thickness of 1 nm and a width of 100–1,000 nm [5]. In general, layered inorganic materials are hydrophilic because the anions on the surface exist in a form that is stabilized with an alkali metal cation. Therefore, polymer materials including -OH groups are known to exhibit very good dispersibility and compatibility with clay. Several methods are used to increase the physical properties of the blend, including hydrogen bonding using the hydroxyl (-OH) group between the polymer chain and the filler [3]. In this study, the diamine monomers—bis(3-aminophenyl)sulfone (BAS) and bis(3-amino-4-hydroxyphenyl) (BAS-OH)—were allowed to react with 4,4'-(hexafluoroisopropyl (6FDA)) as a dianhydride to synthesize two PIs. PI hybrids were prepared from the synthesized PIs and Cloisite 30B as an organoclay. Cloisite 30B is hydrophilic because it has -OH groups. Furthermore, it is expected that the affinity of this clay will increase if it is blended with PI containing -OH group. BAS-OH containing a hydroxyl group can enhance the reactivity, dispersibility, and compatibility between the synthesized PI and clay. In this study, the thermo-mechanical properties, morphology, and optical transparency of the PI hybrids with various concentrations of organoclay (from 0 to 1 wt%) were investigated, and their results were compared. We also described the effect of -OH groups in PI hybrids and compared the properties of the two PI hybrids synthesized using BAS and BAS-OH diamine monomers. Acknowledgment: This research was supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF), funded by the Ministry of Education (2018R1D1A1B07045502). Reference 1. Liu, Z.; Xu, J.; Chen, D.; Shen, G. Chem. Soc. Rev. 2015, 44, 161–192. 2. Liu, J.-M.; Lee, T.M.; Wen, C.-H.; Leu, C.-M. J. Soc. Inf. Disp. 2011, 19, 63–69. 3. Yeun, J.-H.; Bang, G.-S.; Park, B.J.; Ham, S.K.; Chang, J.-H. J. Appl. Polym. Sci. 2006, 101, 591–596.