Effect of Photoacid Generator on Surface Wettability Controllable Polyimides by UV Light Irradiation

Abstract

The authors have systematically investigated the surface wettability controllable polyimides by UV light irradiation using the polyimides having long-chain alkyl or bulky alkyl groups on their side chains. In this paper, the effects of the addition of photoacid generator or photobase generator were examined. As a result of examining the UV light irradiation (λmax; 254 nm) onto the polyimides based on the diamine monomer having long-chain alkyloxy groups and phenyl ester linkage (12G1-AG-terphenyl diamine), it was proven that the addition of the photoacid generator was effective for the surface wettability control from hydrophobicity to hydrophilicity. On the other hand, the addition of photobase generator was not effective. Therefore, it is speculated that the photoreaction activated by the acid catalyst such as an acid catalyzed ether cleavage and acid catalyzed photo-Fries rearrangement enhance the generation of hydrophilic groups such as hydroxyl groups after UV light irradiation. In case that the suitable photoacid generator were selected, the surface wettability control of these polyimides by UV light irradiation (λmax; 365 nm) were accomplished. The utilization of the UV light (λmax; 365 nm) is the merit in the practical use. From the result of ATR analyses, it is recognized that the hydrophobic alkyl groups on the polyimide surface decrease and the hydrophilic groups such as hydroxyl groups generate on their surface.

Reversible Control of Surface Wettability of Polyimides Having Azobenzene Group on Their Side-chain by UV-Vis Light Irradiation

“…The authors also have investigated the surface wettability control of polyimides having various functional groups such as long-chain alkyl groups, t-Boc group, etc. by UV light irradiation [7][8][9][10][11][12][13][14][15][16][17]. However, these wettability changes are irreversible from the hydrophobicity to the hydrophilicity by UV light irradiation.…”

“…The polyimides having azobenzene group on their side chain were synthesized from 3,4'-ODPA or DSDA, as a tetracarboxycilic dianhydride and a novel functional diamine monomer, Azo-DA. Two step polymerization systems including poly(amic acid)s synthesis and chemical imidization were performed as a same manner as previously reported [7][8][9][10][11][12][13][14][15][16][17]. The chemical structures of obtained polyimides are shown in Fig.…”

Surface Wettability Controllable Polyimides Bearing t-Boc Group by UV Light Irradiation

“…Concerning on the reaction mechanism in the case of the addition of PAG, it is speculated that the acid species generated from PAG by UV light irradiation cause the deprotect of t-Boc group as illustrated in Figure 5. Although we have demonstrated the heating in the photo irradiation process made the wettability change somewhat accelerate [16], the heating or post-bake experiment was not examined because the enough wettability changes were recognized even at room temperature. In chemically amplified photo resists, the heating process is necessary to diffuse the acid species in whole polymer film [18].…”

“…Various approaches such as the use of repellent pore-structured polyimide films [9], the surface energy controlled ink-jet printing with UV irradiation [10], have been investigated to obtain the fine patterning. The authors also have investigated the surface wettability control of polyimides bearing longchain alkyl groups by UV light irradiation [8,[11][12][13][14][15][16]. Until now, the authors have been mainly investigated the surface wettability control by UV irradiation (λmax; 254 nm).…”

Surface Wettability Controllable Polyimides by UV Light Irradiation for Printed Electronics

“…Various approaches such as the use of repellent pore-structured polyimide films [5], the surface energy controlled ink-jet printing with UV irradiation [6], have been investigated to obtain the fine patterning. Recently, the authors also have investigated the surface wettability control of polyimides having hydrophobic groups such as long-chain alkyl groups by UV light irradiation [7][8][9][10][11][12][13]. The basic concept of these surface wettability controllable polyimides is shown in Figure 1.…”