Convergent Synthesis of Polyimide Dendrimers from an ABB' Intermediate

摘要

A convergent synthetic approach was applied to 4-(2, 4-diaminophenoxy)phthalic acid ethyl esters (DAPPAcE) by reacting it with mono-anhydride in each successive step and this approach was found to be highly efficient in getting three generations of PI dendrimers than all known dendritc strategies carried out so far in PI preparation. The structures of prepared PI dendritic anhydride intermediates of three generations, [A] and PI dendrimers, [B], were all positively characterized by 1H-NMR, FT-IR and mass spectrometry. GPC analyses showed molecular weight distributions are 1.02 (for [G-1][B]), 1.04 (for [G-2][B]) and 1.07 (for [G-3][B]) indicating that they all possess narrow molecular distributions. All PI dendrimers have excellent thermal properties. The 5wt % loss temperature of intermediates[G-X][A] (X=1, 2, and 3) are between 383°C and 390°C, while their respective [G-X][B] PI dendrimers(X=1, 2, and 3) are between 412°C and 421°C. [G-X][B] (X=1, 2, and 3). They all exhibit good solubility behaviors in most organic solvents, and their solubility do not show any appreciable difference between generations.