Synthesis of photocrosslinkable hyperbranched polyesters and their film properties

Hyperbranched polyesters with terminal methacryloyl groups (HBPEAc) were synthesized by the one-pot polyaddition of bisphenol A diglycidyl ether and trimesic acid in the presence of methacrylic acid with a number-average molecular weights of 5100-7700 in 70-83% yields. The photoradical polymerization of HBPEAc was examined in the presence of 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-2-one (Irgacure 907 (R)) as a photoinitiator in the film state upon UV irradiation to afford the corresponding cured films quantitatively. The crosslinking densities of the cured films of HBPEAc were higher than those of the corresponding linear ones, and birefringence cannot be detected for the cured films of HBPEAc because of their random structures. Furthermore, an alkaline-developable hyperbranched polyester containing pendant carboxyl groups (HBPEAc-COOH) was prepared by the addition reaction of HBPEAc with cis-1,2,3,6-tetrahydrophthalic anhydride, and its patterning properties were examined to give the resolution of a 55-mu m-line and 275-mu m-space pattern by UV irradiation with 700 mJ/cm(2). (c) 2005 Wiley Periodicals, Inc.