Synthesis and characterization of dendritic poly(ether imide)s

New dendritic poly(ether imide)s were synthesized by the convergent growth approach, using 1-(4-aminophenyl)-1,1-bis(4-hydroxyphenyl)ethane as the bui lding block. The aromatic nucleophilic substitution of the building block w ith 3-nitro-N-phenylphthalimide led to the first-generation dendron with am inophenyl group at the focal point, which was subsequently reacted with 3-n itrophthalic anhydride to yield the dendritic wedge containing an activated nitro group; The resulting nitro functionality was allowed to react with t he building block to give the second-generation dendron, which was then con densed with 3-nitrophthalic anhydride, followed by ring closure to re-form the phthalimide ring and restore a reactive nitro group. Through an aromati c nucleophilic substitution, the dendritic wedges with an activated nitro g roup were coupled to the polyfunctional core to form the dendritic macromol ecules. Structures of the ether-imide dendrimers were fully characterized b y use of a combination of techniques including H-1 NMR, C-13 NMR, IR, and m ass spectrometry. The glass transition temperature of the dendrimers increa sed with molecular weight, and the variation was consistent with theoretica l calculations. These dendritic poly(ether imide)s are soluble in various o rganic solvents and had a thermal stability comparable to linear poly(aryl ether imide)s.