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.
Monomers, namely, 6FDA
and TeMPD, were purchased from Aldrich Inc.
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) .
(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.
ODA (99% purity: Aldrich), and 6FDA
(99.9% purity; Aldrich), were used as received.
Membrane thickness used for the experiments was between 55 and 85 [micro] m for each dried 6FDA
- TeMPD polyimide membrane.
and APS were also commercially available, and were used as received.
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.