Abstract: A wet phase inversion process of polyamic acid (PAA) allowed fabrication of a porous membrane of polyimide (PI) with the combination of a low dielectric constant (1.7) and reasonable mechanical properties (Tensile strain: 8.04%, toughness: 3.4 MJ/m3, tensile stress: 39.17 MPa, and young modulus: 1.13 GPa), with further thermal imidization process of PAA. PAA was simply synthesized from purified pyromellitic dianhydride (PMDA) and 4,4-oxydianiline (ODA) in two different reaction solvents such as γ-butyrolactone (GBL) and N-methyl-2-pyrrolidinone (NMP), which produce Mw/PDI of 630,000/1.45 and 280,000/2.0, respectively. The porous PAA membrane was fabricated by the wet phase inversion process based on a solvent/non-solvent system via tailored composition between GBL and NMP. The porosity of PI, indicative of a low electric constant, decreased with increasing concentration of GBL, which was caused by sponge-like formation. However, due to interplay between the low electric constant (structural formation) and the mechanical properties, GBL was employed for further exploration, using toluene and acetone vs. DI-water as a coagulation media. Non-solvents influenced determination of the PAA membrane size and porosity. With this approach, insight into the interplay between dielectric properties and mechanical properties will inform a wide range of potential low-k material applications.
Keywords: low K material; porous polyimide; poly amic acid; wet phase inversion
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Kim, S.; Jang, K.-S.; Choi, H.-D.; Choi, S.-H.; Kwon, S.-J.; Kim, I.-D.; Lim, J.A.; Hong, J.-M. Porous Polyimide Membranes Prepared by Wet Phase Inversion for Use in Low Dielectric Applications. Int. J. Mol. Sci. 2013, 14, 8698-8707.
Kim S, Jang K-S, Choi H-D, Choi S-H, Kwon S-J, Kim I-D, Lim JA, Hong J-M. Porous Polyimide Membranes Prepared by Wet Phase Inversion for Use in Low Dielectric Applications. International Journal of Molecular Sciences. 2013; 14(5):8698-8707.
Kim, Soohyun; Jang, Keon-Soo; Choi, Hee-Dok; Choi, Seung-Hoon; Kwon, Seong-Ji; Kim, Il-Doo; Lim, Jung A.; Hong, Jae-Min. 2013. "Porous Polyimide Membranes Prepared by Wet Phase Inversion for Use in Low Dielectric Applications." Int. J. Mol. Sci. 14, no. 5: 8698-8707.