Synthesis of Photocrosslinkable Hyperbranched Polyesters with Terminal Methacryloyl Groups by the One-pot Polyaddition of Bis(oxetane)s with 1,3,5-Benzenetricarboxylic Acid and Methacrylic Acid

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 % Irgacure907® as a photo-initiator, 24 wt % epoxy resin, and 1 wt % dicyandiamide achieved a resolution of a 55 μm line pattern and a 27 μm space pattern by UV irradiation (1000 mJ) when 6 μm thick film is used.