Sorry, I think it is not possible to export/import full materials from/to UE, there's no such capabilities in editor. Even more, the engine is extensible in this area, so if material uses some custom node added for specific game, you will not be able to reproduce this material in another engine (say, UDK).
hi gildor,
thanks for your answere, yes the shader technique in arkham knight is advanced e.g. PBR. But this is not important for me. I need not the full shader tree, for me is enough when i can read segments from this shader in a text file.
or saving it into some readable format, for possibility to learn how it works.
That would be awesome.

I can send you a test file from the game.
regards,
ut2003