Dendritic poly(ether–imide)s: synthesis, characterization, and modification

A convergent approach to the preparation of dendritic macromolecules with an aromatic ether–imide inner structure and modifiable benzyl ether chain ends is described. The structural component that constitutes the branching regions was derived from 1-(4-aminophenyl)-1,1-bis(4-hydroxyphenyl)ethane. The key steps in ether–imide dendron synthesis involve an aromatic nucleophilic displacement of an activated nitro group with phenoxide leading to the ether linkage and cyclocondensation of the amino group with 3-nitrophthalic anhydride, to give rise to the imide ring containing an activated nitro functionality. The dendritic wedges are then coupled to a polyfunctional core to complete the synthesis. The benzyl ether chain ends can be selectively removed by catalytic hydrogenolysis to produce a dendrimer with phenolic chain ends. Further modification of the chain ends is accomplished by etherfication of the phenolic groups. Structures of these dendritic poly(ether–imide)s were confirmed by 1H NMR, 13C NMR and FTIR spectroscopy as well as by mass spectrometry. Properties such as the glass transition temperature and solubility of the dendrimer are greatly affected by the nature of the end groups.