In order to obtain thermoplastic (before curing) and thermosetting (after curing) polyimides with high T-g for adhesive film, we prepared novel polyimides having phenylethynyl group in the side chain (44% of concentration of curing group) from asymmetric 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 3,4'-oxydianiline (3,4'-ODA) or 1,3-bis(4-aminophenoxy)benzene (1,3.4-APB) or 1,3-bis(3-aminophenoxy)benzene (1,3,3-APB), and 2,4-diamino-1-(4-phenylethynylphenoxy)benzene (mPDAp). Among three kinds of polymer, uncured polyimide of a-BPDA/1,3,4-APB; mPDAp had rather high T-g (265 degrees C, DMA) and thermoplasticity (E' drop > 10(3) at 7). After curing reaction of phenylethynyl group, the T-g of the polyimide was increased dramatically (364 degrees C, DMA). The polyimide derived from 1,3,4-APB having less concentration of curing group (20%) was also prepared to improve further film flexibility and toughness. (c) 2005 Elsevier Ltd. All rights reserved.