High temperature transparent material is transparent material that can withstand processing above 250 ℃. Mainly used for flexible solar cell floor, liquid crystal display ITO floor instead of fragile glass floor, liquid crystal display orientation film, for communication connection waveguide material and for flat optical line half wave board. Among the currently available materials, polymers that require TG far above 250 ° C, polyimides should be preferred materials. However, polyimides are generally yellow-brown transparent material. From the molecular design, polyimide to increase the structural principle of transparency is to avoid or reduce the conjugated units, reducing the intramolecular and molecular load transfer. The specific structural design is:
1. A fluorine-containing group is introduced
2. The introduction of larger substituents, such as circular structure and other large side groups.
3. The introduction of substituents at the 2,2 & apos; -position of the biphenyl gives rise to a non-coplanar structure, disrupting a wide range of conjugates.
4. The introduction of fats, especially alicyclic structural units.
5. Monomers such as 3,4'-dianhydride and 3,3'-dianhydride, meta-substituted diamines and the like can be used to bend the backbone.