SYNTHESIS AND PROPERTIES OF POLYIMIDES CONTAINING 2,2'-BIPYRIDINE DERIVATIVES

A series of polyimides containing 2,2'-bipyridine, 7, were synthesized by reaction of 4,4'-diamino-2,2'-bipyridine (4) with various aromatic dianhydrides, followed by imidization upon heating. These polyimides are fairly thermostable, and 5% weight loss occurs in the range of 484 degrees C-580 degrees C. The glass transition temperatures are betwee n 276 degrees C and 313 degrees C. Their poly(amic acids) 6 can be par tially quaternized using 1,2-dibromoethane and then easily imidized up on heating. The temperature of quaternized polyimides at which 5% weig ht loss is observed is around 300 degrees C, the glass transition temp eratures range from 202-239 degrees C. These quaternized polyimides ca n also develop color under UV irradiation in a poly(N-vinyl-2-pyrrolid one) (PVP) matrix with maximum absorption at 800 nm. The bipyridine-ba sed poly(amic acids) 6 can trap various metal ions from solution and t hen can be imidized by heating. The XPS data indicate the formation of a 1:1 (bipyridine: metal molar ratio) complex and a 2:1 complex. The temperature at which for the polyimide-metal complexes 5% weight loss is observed is around 300 degrees C. Both the poly(amic acid)-metal co mplex and the polyimide-metal complex catalyze the condensation of ben zaldehyde with acetophenone, with yields of chalcone of ca. 6.7-31.7%. The order of catalytic activity for different metal ions is Zn(II) > Co(II) > Cu(II).