کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1526886 | 1511852 | 2008 | 6 صفحه PDF | دانلود رایگان |
A series of aromatic hyper-branched polyimides were successfully prepared by condensation polymerization of commercially available A2-type dianhydride monomers 4,4-biphthalic anhydride (BPAD) and 3,3′,4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA) with the BB2′-type triamine monomer 2,4,6-triaminopyrimidine (TAP). The hyper-branched polyimides, with two different terminated groups, were obtained from the reactions between different molar ratios of the TAP and the dianhydrides. Both Fourier transform infrared (FT-IR) and 1H NMR spectroscopy were used to verify the molecular structures of the obtained hyper-branched polyimides. The molecular weights were determined by gel permeation chromatography (GPC). The results suggested that the amine-terminated hyper-branched polyimides displayed lower degrees of branching and molecular weights than the corresponding anhydride-terminated ones. However, the anhydride-terminated hyper-branched polyimides showed a relatively lower glass transition temperature, obtained by differential scanning calorimetry, which could be attributed to the increased free volume and mobility of the macromolecules caused by the absence of chain-end interactions. Thermogravimetric analysis (TGA) results indicated that the hyper-branched polyimides had excellent thermal stabilities, the amine-terminated hyper-branched polyimides showing higher thermal stabilities than those of the anhydride-terminated ones.
Journal: Materials Chemistry and Physics - Volume 108, Issues 2–3, 15 April 2008, Pages 214–219