Synthesis and properties of nem aromatic polyimides - Polymeric materials for light-emitting and liquid-crystal displays

Abstract

New aromatic diamines containing pi-conjugated heterocyclic rings were synthesized, which emit blue light in the photoluminescence. Using these new monomers, soluble poly(amic acid)s were prepared by the polycondensations with pyromellitamic dianhydride, and thermally converted to the polyimides in films which emit intense blue-light. These polyimides are considered as potential candidate materials for fabricating optoelectronic devices which emit blue light. In addition, new poly(m-phenylene 4,4'-oxydiphthalimide)s containing various side chains were synthesized. For these polyimides, thermal properties were investigated with considering the chain flexibility of polymer backbone as well as the spacer and biphenyl mesogen end group in the side chains. In particular, these polyimides exhibited excellent performance in the rubbing process and the controlling of both the alignment and the pretilt of liquid-crystal (LC) molecules in the LC cell. This might be attributed mainly to a strong interaction between the biphenyl mesogen end group in the side chains and the mesogen unit of LC molecules.