6FDA2,2'-Bis (3,4-Dicarboxyphenyl) Hexafluoropropane Dianhydride
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ODPA, BPDA, 6FDA, 2,2-bis(4-[4-amino phenoxy] phenyl) hexafluoropropane (HFBAPP), 4,4'-(hexafluoroisopropylidene)dianiline (6FpDA), 1,3,5-triformylbenzene, 1,4-diaminobenzene and 1,4-dioxane were procured from Sigma Aldrich and used as-received.
4,4'-(Hexafluoroisopropylidene)diphthalic anhydride (6FDA) (Aldrich, Czech Republic) was heated to 160[degrees]C for 5 h in vacuum prior to use.
batch-wise addition of 6FDA (an equimolar amount) was carried out into the CNT-ODA suspension (6FDA:ODA = 1:1).
The monomers used in the synthesis of PI, 6FDA and TeMPD were used as-received without further purification.
Previously, we reported that the synthesis and gas permeation properties of novel telechelic polyimides are composed of 6FDA and TeMPD end-capped with the UV-reactive group, 1,1-bis(acryloyloxy methyl) ethyl isocyanate (BEI) [24].
6FDA (5.016 g, 1.129 X [10.sup.-2] mol) equimolar amount of DADE) was added to the DMAc solution at a concentration of 20 wt% with stirring.
High-purity chemicals: EpicIon (DOCDA; Merk, 98% purity), p-phenylenediamine (PPD, Aldrich, 99%), 4,4'-oxy-dianiline (ODA, Aldrich, 99% purity), and 4,4'-(hexafluoroi-sopropyldiene) diphtalic dianhydride (6FDA), Aldrich 99.9% purity) were used as received.
Membrane thickness used for the experiments was between 55 and 85 [micro] m for each dried 6FDA - TeMPD polyimide membrane.
A series of polyimide oligomers endcapped with 4-phenylethynylaniline have been prepared using the chemical compositions as shown in Table 1, in which PI-1 to PI-4 were prepared by the reaction of a diamine mixture of 1,3,4-APB and 3,4'-ODA at mole ratio of 75:25 with four different aromatic anhydrides including ODPA, BPDA, 6FDA, and 9FDA, respectively.