ABSTRACT:The hyperbranched poly(ester)s with pendant primary hydroxy, methacryloyl, and oxetanyl groups were synthesized by the one-pot method for the polyaddition of bis(oxetane)s with 1,3,5-benzenetricarboxylic acid (TMA) and methacrylic acid (MA) in the presence of tetraphenylphosphonium chloride (TPPC) as a catalyst. A alkaline-developable photo-reactive hyperbranched polymer (P-4b) was prepared by the addition reaction of the synthesized hyperbranched poly(ester) P-4a with cis-1,2,3,6-tetrahydrophthalic anhydride (THPA). A resist composed of 58 wt % P-4b, 12 wt % dilute monomer, 5 wt % Irgacure907Ò as a photo-initiator, 24 wt % epoxy resin, and 1 wt % dicyandiamide achieved a resolution of a 55 mm line pattern and a 27 mm space pattern by UV irradiation (1000 mJ) when 6 mm thick film is used. 1,2 such as coatings, printing inks, adhesives, photo-resists, and solder masks, because of their low volatile organic compound (VOC), high productivity, excellent physical properties, and energy saving. Recently, these systems have also been applied to electronics and information technology fields 3 such as display, CD, DVD, optical-fiber, and opticaldevice. In these curing systems, acrylate monomers and oligomers are mainly used due to their high reactivity. Most of acrylate oligomers such as acrylated epoxy resins, poly(urethane)s, poly(ester)s, and poly-(ether)s have relatively high viscosity, because these oligomers were composed from linear polymer chains in general.More than 30 years ago, we 4,5 reported the synthesis of polyesters with pendant hydroxy groups and (meth)acrylate groups by the addition reaction of epoxy resins with (meth)acrylic acid, which have been used as main resins in the fields of coatings and printing inks due to their high photochemical reactivity and excellent mechanical property. Furthermore, these oligomers were modified 6 with cyclic carboxylic anhydride to form photo-curable oligomer with alkaline developable property. These (meth)acrylated epoxy resin derivatives have been widely used as main resin in solder masks in the world.Meanwhile, hyperbranched polymers (HBPs) containing a large number of terminal groups possess a randomly branched structure 7 and have recently attracted a great deal of attention for their unique properties such as lower viscosity, good solubility and many reactive terminal groups compared with the corresponding linear ones. Condensation polymers with hyperbranched structure are mainly synthesized 8,9 by the one-step self-polycondensation of an AB m type monomer which has one 'A' functional group and multiple 'B' functional groups. However, these monomers are generally required to process tedious multistep organic synthesis and are unsuitable for industrial application on a large scale synthesis. To overcome this technical problem, Kakimoto and his co-workers 10 substituted a new method by conventional combination of A 2 and B 3 monomers. Since the reaction system between A 2 þ B 3 monomers produced gel products in general, the control of the reaction conditio...