Synthesis, characterization, and comparison of properties of novel fluorinated poly(imide siloxane) copolymers

Abstract

Four new poly(imide siloxane) copolymers were prepared by a one-pot solution imidization method at a reaction temperature of 1808C in ortho-dichlorobenzene as a solvent. The polymers were made through the reaction of o-diphthaleic anhydride with four different diamines-4,4 0 -bis(p-aminophenoxy-3,3 00 -trifluoromethyl) terphenyl, 4,4 0 -bis(3 00 -trifluoromethyl-p-aminobiphenyl ether)biphenyl, 2,6-bis(3 0 -trifluoromethyl-p-aminobiphenyl ether)pyridine, and 2,5-bis(3 0 -trifluoromethyl-p-aminobiphenylether)thiopeneand aminopropyl-terminated poly-dimethylsiloxane as a comonomer. The polymers were named 1a, 1b, 1c, and 1d, respectively. The synthesized polymers showed good solubility in different organic solvents. The resulting polymers were well characterized with gel permeation chromatography, IR, and NMR techniques.1 H-NMR indicated that the siloxane loading was about 36%, although 40 wt % was attempted.29 Si-NMR confirmed that the low siloxane incorporation was due to a disproportionation reaction of the siloxane chain that resulted in a lowering of the siloxane block length. The films of these polymers showed low water absorption of 0.02% and a low dielectric constant of 2.38 at 1 MHz. These polyimides showed good thermal stability with decomposition temperatures (5% weight loss) up to 4608C in nitrogen. Transparent, thin films of these poly (imide siloxane)s exhibited tensile strengths up to 30 MPa and elongations at break up to 103%, which depended on the structure of the repeating unit. The rheological properties showed ease of processability for these polymers with no change in the melt viscosity with the temperature.

Syntheses and Characterizations of Soluble PDMS-Grafted Polyimides

“…The results are summarized in Table II. These polymers were soluble in chloroform, which would be due to the presence of hydrophobic polydimethylsiloxane segments in the side chain [14,15]. In addition, FPI-g-PDMS and MPI-g-PDMS exhibited the high solubility, which were soluble in chloroform, THF, DMF and NMP, while PI-g-PDMS was soluble only in chloroform.…”

“…In particular, the graft polyimide of FPI-g-PDMS and MPI-g-PDMS were soluble in toluene, benzene and acetone. Therefore, FPI-g-PDMS and MPI-g-PDMS showed a relatively higher solubility compared to the other PDMS/polyimide polymers [13][14][15][16][17].…”

“…2. FT-IR spectra of all PDMS-grafted polyimide membranes shows the sharp absorption bands at about 1770 cm -1 (C=O symmetric stretching), 1710 cm -1 (C=O asymmetric stretching), 1378 cm -1 (C-N strethching) corresponding to the chracteristic imide bands [11][12][13][14][15][16][17]. In addition, the absorptions of the Si-O-Si are observed at 1080 and 1000 cm -1 .…”

“…In order to improve the processability, the introduction of flexible linkages and bulky units into the aromatic groups were investigated [10][11][12]. Furthermore, several random or block copolymers have been prepared by incorporation of flexible polydimethylsiloxane (PDMS) components into the polyimide main chains [13][14][15][16][17]. These copolymers exhibited the higher solubility, the lower water adsorption and the lower dielectric constants, as compared with pure polyimide.…”

Effect of polydimethylsiloxane incorporation on the properties of polyimides synthesized from newly designed α,α'-bis(2-aminophenoxy)-p-xylene

“…improved solubility and flame resistance, increased permeability, permselectivity, adhesive ability and impact resistance, reduced water absorption and dielectric constant, modified surface properties, superior electrical properties etc. [21][22][23][24][25][26][27]. Therefore, silicone containing polyimides have attracted significant attention recently and studies are mainly focused on investigating the effects of polydimetylsiloxane incorporation on the aforementioned properties of polyimides.…”