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For the development of chlorine-resistant nanofiltration membranes, a thin-film-composite membrane was prepared by the interfacial polymerization of N-phenylethylenediamine and 1,3,5-benzenetricarbonyl trichloride on a microporous polysulfone support substrate. The polymerization on the substrate surface was confirmed by Fourier transform infrared measurements, and membrane surface properties such as the roughness and f potential were characterized. Rejections of NaCl and isopropyl alcohol of the prepared membrane were 95 and 50%, respectively. The membrane showed much higher chlorine resistance than a commercial polyamide membrane when the membranes were immersed in an aqueous NaOCl solution. A field test was carried out with a spiral-type membrane module. Tap water was treated by this module for more than 70 days under the condition of continuous NaOCl injection. The prepared membrane module was quite stable, and no distinguished change in the rejection and flux was recognized.

A negative-working photosensitive polyimide (PI) precursor based on a low dielectric polyimide precursor having a low coefficient of thermal expansion (CTE) and 1,4-dihydropyridine (DHP) as a photosensitive compound has been developed. Co-polyamic acid(Co-PAA)s were prepared by ring-opening polyaddition of aromatic dianhydrides with diamines. The dissolution behavior of Co-PAAs containing DHP after exposure was studied and it was found that the difference of dissolution rate between the exposed and unexposed parts was enough to get a high contrast due to the photochemical reaction of DHP in the polymer film. The cured Co-PI film at 3 80 °C showed the low coefficient of thermal expansion of 20 ppm and the low dielectric constant of 2.7 at 1 MHz.