Abstract
A novel terphenyl diamine monomer, 4-[3,5-Bis(3-aminophenyl)benzophenone] phenyl 3,4,5-tris(decyloxy)benzoate (TerKetone) having three long-chain alkyl groups connected by phenylester and benzophenone linkages was synthesized via several step reactions from Gallic acid methyl ester. The novel polyimides and copolyimides were synthesized from 3,4’-ODPA as a dianhydride, TerKetone, and 4,4’-diaminodiphenylether (DDE) as a diamine co-monomer by two step polymerization systems. The thin films of obtained polyimides were irradiated by UV light (λmax; 254 nm), and the contact angles for the water decreased from near 100° (hydrophobicity) to near 40° (hydrophilicity) in proportion to irradiated UV light energy. From the result of surface analyses (ATR, XPS, AFM), it is recognized that the hydrophobic long-chain alkyl groups on the polyimide surface decrease and the hydrophilic groups such as hydroxyl groups and carboxyl groups generate on their surface. Furthermore, it was observed that the incorporation ratios of TerKetone in copolyimides affected the changes of wettability by UV light irradiation.
