Process for the isolation of polymer fractions

摘要

The invention relates to a process for isolating, from a polymer comprising repeating units which are individually of Formula Xin whichY is P or N,Ar<1 >& Ar<2 >are bivalent aromatic groups,Ar<3 >is a monovalent aromatic group, andthe units of Formula X may be the same or different,a molecular weight fraction which is especially suitable for use as a charge transport material.