Browsing by Author "Shiea, J"

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Dendritic poly(ether-imide)s: synthesis, characterization, and modification
(2001-03-01)
Leu, CM
;
Shu, CF
;
Teng, CF
;
Shiea, J
;
應用化學系
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(etherimide)s were confirmed by H-1 NMR,C-13 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. (C) 2000 Elsevier Science Ltd. All rights reserved.
Synthesis and characterization of dendritic poly(ether imide)s
(2000-04-18)
Leu, CM
;
Chang, YT
;
Shu, CF
;
Teng, CF
;
Shiea, J
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 building block. The aromatic nucleophilic substitution of the building block with 3-nitro-N-phenylphthalimide led to the first-generation dendron with aminophenyl group at the focal point, which was subsequently reacted with 3-nitrophthalic anhydride to yield the dendritic wedge containing an activated nitro group; The resulting nitro functionality was allowed to react with the building block to give the second-generation dendron, which was then condensed with 3-nitrophthalic anhydride, followed by ring closure to re-form the phthalimide ring and restore a reactive nitro group. Through an aromatic nucleophilic substitution, the dendritic wedges with an activated nitro group were coupled to the polyfunctional core to form the dendritic macromolecules. Structures of the ether-imide dendrimers were fully characterized by use of a combination of techniques including H-1 NMR, C-13 NMR, IR, and mass spectrometry. The glass transition temperature of the dendrimers increased with molecular weight, and the variation was consistent with theoretical calculations. These dendritic poly(ether imide)s are soluble in various organic solvents and had a thermal stability comparable to linear poly(aryl ether imide)s.