Regeneration of polycondensation of wholly aromatic poly(azomethine)s with1,5-or 2,6-substituted naphthalene moiety in main chain

Wholly aromatic poly(azomethine)s with 1,5- or 2,6-substituted naphthalene moiety in the main chains were prepared in aprotic polar solvents or m-cres ol under various reaction conditions. In the polymerization of 1,5-diaminon aphthalene with terephthalaldehyde, the polymer that synthesized in (HMPA/D MSO) at room temperature for 24 h by adding 5 wt % of calcium chloride and a very small amount of p-toluenesulfonic acid showed the highest reduced vi scosity in all of the polymers from 1,5-diaminonaphthalene. The reduced vis cosity of poly(azomethine)s synthesized from 2,6-diaminonaphthalene with 2, 6-diformylnaphthalene in m-cresol and with terephthalaldehyde in HMPA/DMSO were eta(red) = 0.35 and 0.36, respectively. The thermal analysis showed th e poly(azomethine)s had high thermal stability and the glass-transition tem peratures of these polymers are about 250 degrees C. The X-ray diffraction showed that they are partially crystalline. They could be polymerized again by second stage polycondensation in polyphosphoric acid. The reduced visco sities of the obtained polymers were about 2-5 times as high as that of the pristine polymers. (C) 2000 John Wiley & Sons, Inc.