Photo-Induced Polarity Change of Photosensitive Polyimide with o-Nitrobenzyl Ester Side Chain

Abstract

Photochemical reaction of the pendant o-nitrobenzyl ester of the polyimide films was investigated in details by FT-IR and UV-vis absorption spectra to confirm the generation of the corresponding carboxylic acid group. The conversions of the pendant o-nitrobenzyl ester increased with irradiation time and reached to 38-46% under 60 min irradiation. Water contact angle of PSPI 1-4 films decreased from 75° to below 55° after UV irradiation for 60 min followed by rinse treatment with toluene, in which o-nitroso benzaldehyde as a side product of the photochemical reaction was removed, due to the generation of carboxylic acid group. It was found that photochemical reaction of the pendant o-nitrobenzyl ester in the polyimide film having high T g s proceeded in middle conversion to induce water contact angle change as 20°.

Surface Wettability Controllable Polyimide Bearing <i>o</i>-Nitrobenzyl Group by UV Light Irradiation

“…In addition, the energy efficiency of 254 nm UV irradiation is worse than the one of 365 nm UV irradiation that is preferable wavelength in industry. Consequently, we have focused on o-NO 2 Bn group that is the protecting group of phenolic hydroxyl group and easily deprotected by UV light irradiation at 365 nm [18,19] ), 2925 (C-H), 1720 (C=O) cm -1 , 1520 (NO 2 ) cm -1 .…”

The improved photosensitivity of photosensitive polyimides containing o‐nitrobenzyl ether groups induced by the addition of photoacid generator

“…In the FT‐IR spectrum (Figure 5(a)), the peak corresponding to the NO 2 of the Nb photosensitive group was observed at 1525, 1359, 858 cm −1 . Furthermore, in the NMR spectrum (Figure 5(b)), the proton peak corresponding to the benzylic CH 2 group of ODA‐5‐PSPI was observed at 4.9 ppm 17,24,25 . Therefore, compared with the characteristic peak of Nb (4.9 ppm) and benzene peaks, we could estimated that the Nb was introduced to ODA‐5‐PI as 88 mol%.…”

“…Furthermore, in the NMR spectrum (Figure 5 (b)), the proton peak corresponding to the benzylic CH 2 group of ODA-5-PSPI was observed at 4.9 ppm. 17,24,25 Therefore, compared with the characteristic peak of Nb (4.9 ppm) and benzene peaks, we could estimated that the Nb was introduced to ODA-5-PI as 88 mol%.…”

“…Accordingly, the photosensitivity or responsibility of photosensitive groups is among the important factors for determining the resolution of micropatterns. 18 So far, numerous photosensitive groups have been used for PSPI, such as t-Boc, 19 DNQ groups, [20][21][22][23] and onitrobenzyl group (Nb) 17,[24][25][26][27][28] derivatives. Among them, Nb derivatives are well-known to be photocleavages by rearrangement mechanisms.…”