| 초록 |
New asymmetric aromatic diamine with methyl group at the ortho position of amino group has been developed to prepared transparent aromatic polyimides (PIs) in the visible region. All aromatic PIs derived from 4-(4-aminophenoxy)-2,6-dimethylaniline (APDMA) and aromatic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4'-oxydiphthalic anhydride (ODPA), 4,4'-biphthalic anhydride (BPDA), and pyromellitic dianhydride (PMDA) were prepared via a two-step polycondensation. All PIs showed good thermal properties, such as 5% weight loss at temperatures range of 510-529 oC and glass transition temperature above 290 oC. The PIs exhibited good optical transparency such as cut-off wavelength in the region of 296-358 nm and above 92-99% at 550 nm. In addition, all PIs showed low refractive indices in the range of 1.567-1.637 at wavelength of 637 nm and low birefringence. |
