Abstract
The intermolecular crosslinks and the changes in polymer coil dimension during the competitive intra-and intermolecular photocrosslinking reactions were studied for polyimides of benzophenoneteracarboxylic dianhydride with oligomers having various degrees of bis(aminopropyl) polydimethylsiloxane (BAPSX, n=8, 15, 61) in tetrahydrofuran under u.v.irradiation at 30°C. The magnitude of Mw, <s2>1/2, and A2 was evaluated by a light-scattering measurement. The deviation of the intermolecular crosslinks from linearity during the reaction becomes more pronounced as the initial polymer concentration decreases or the number of BAPSX oligomers in a polyimides increases. The value of Φinter/[C]θ for a polyimide with a BAPSX oligomer (n=8) was determined to be 6.7×102 dm3 mol-1 in the early stage of crosslinks formation. The extent of the contraction of polymer coils due to intramolecular crosslinking increases as the number of BAPSX oligomers in a polyimide decreases.
