High-performance aromatic polyamides

Fluorinated high-performance polymers: Poly(arylene ether)s and aromatic polyimides containing trifluoromethyl groups

Polyimides are proved to be an important class of polymers due to their outstanding set of physical and chemical properties. However, this class of polymers suffers from poor processability, which limits their scope of application. This review article deals with approaches that have been undertaken by different researchers to improve the processability of this class of polymers. Mostly, these are synthetic approaches using new diamine and dianhydride monomers that reduce the interchain interaction of the final poyimide by flexibilizing the polymer chain or increasing the fraction free volume. Accordingly, the structural factors that are responsible for better processability are discussed and representative diamine and diahydride structures are tabulated under different categories. Major efforts towards development of soluble polyimides but maintaining excellent mechanical and thermal properties have been done by our group and are also covered in this article.

Solubility improvements in aromatic polyimides by macromolecular engineering

Effects of internal linkage groups of fluorinated diamine on the optical and dielectric properties of polyimide thin films

Organosolubility and optical transparency of novel polyimides derived from 2′,7′-bis(4-aminophenoxy)-spiro(fluorene-9,9′-xanthene)

Three novel diamine monomers (VI, VII, and VIII) were synthesized. These diamine monomers lead to a number of semifluorinated poly(ether imide)s when reacted with different commercially available dianhydrides like pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropene (6FDA), and oxydiphthalic dianhydride (ODA) by thermal imidization route. Elemental analyses, IR and NMR techniques were used to characterize the monomers and polymers. The resulting polymers exhibited weight average molar masses up to 1.78 × 105 g mol−1 in GPC with respect to polystyrene standard and have very good solubility in several organic solvents such as NMP, DMF, DMAC, DMSO, chloroform, and THF. Very good solubility of these polymers in CDCl3 enables their complete characterization by proton as well as 13C-NMR techniques. The polymers showed very high thermal stability with decomposition temperature (5% weight loss) up to 511°C in air and high glass transition temperature up to 311°C depending upon the exact repeating unit structure. The polymer films showed high modulus (up to 2.9 GPa) as was evaluated by DMA. The polymers also showed very low water absorption (0.16%), low dielectric constant (2.35 at 1MHz) and very good optical transmission. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3025–3044, 2007

Polyimides 7: Synthesis, characterization, and properties of novel soluble semifluorinated poly(ether imide)s

Five new poly(ether imides) have been prepared on reaction with oxydiphthalic anhydride (ODA) with five different diamines: 1,4-bis(p-aminophenoxy-2′-trifluoromethyl benzyl) benzene, 4,4′-bis(p-aminophenoxy-2′-trifluoromethyl benzyl) benzene, 1,3-bis(p-aminophenoxy-2′-trifluoromethyl benzyl) benzene, 2,6-bis(p-aminophenoxy-2′-trifluoromethyl benzyl) pyridine, and 2,5-bis(p-aminophenoxy-2′-trifluoromethyl benzyl) thiophene. Synthesized polymers showed good solubility in different organic solvents. The polyimide films have low water absorption of 0.3–0.7%, low dielectric constants of 2.82–3.19 at 1 MHz, and high optical transparency at 500 nm (>73%). These polyimides showed very high thermal stability with decomposition temperatures (5% weight loss) up to 531°C in air and good isothermal stability; only 0.4% weight loss occurred at 315°C after 5 h. Transparent thin films of these polyimides exhibited tensile strength up to 147 MPa, a modulus of elasticity up to 2.51 GPa and elongation at break up to 30% depending upon the repeating unit structure. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 821–832, 2004

Polyimides 6: Synthesis, characterization, and comparison of properties of novel fluorinated poly(ether imides)

An unsymmetrical diamine monomer 4-(p-aminophenoxy)-3-trifluoromethyl-4'-aminobiphenyl has been synthesized successfully. This monomer leads to the synthesis of different novel poly(ether imide)s when reacted with different dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane (6FDA), and oxy diphthalic anhydride (ODA). The poly(ether imide) prepared from this monomer on reaction with 6FDA is soluble in several organic solvents such as N-methylpyrolidinone (NMP), dimenthylformamide (DMF), N,N-dimethyl-acetamide (DMAc), tetrahydrofuran (THF), and CHCl 3 . The poly(ether imide)s prepared from BTDA and ODA are soluble in NMP, DMF, and DMAc but not in THF or CHCl 3 , whereas the polymer prepared from PMDA is soluble only in NMP. The water uptake value for these poly(ether imide) films is very low (0.2-0.5%), and exhibited low dielectric constants (2.81 at 1 MHz). The polymers exhibited high thermal stability up to 532°C in air for 5% weight loss, and high glass transition temperatures up to 288°C. The polymer exhibited high tensile strength up to 135 MPa, modulus 3.2 GPa, and elongation at break up to 25%, depending on the exact polymer structure.

Novel Semi‐Fluorinated Poly(ether imide)s Derived From 4‐(p‐Aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl

A series of copolymers were prepared by the reaction of various bisphenols with a 50:50 molar ratio of two bisfluoro compounds, 4,4′-bis(1-fluoro-2-trifluoromethyl benzyl) benzene and 4,4′-difluorobenzophenone. The synthesized polymers were well characterized for their thermal, mechanical, and electrical performances. The copolymers showed a better set of properties than their analogous homopolymers derived from 4,4′-bis(1-fluoro-2-trifluoromethyl benzyl) benzene and bisphenols. The microstructures of the copolymers were analyzed by 1H-, 13C-, 19F-, distortionless enhancement by polarization transfer 90, two-dimensional 1H–1H homonuclear correlation spectroscopy, and 13C–1H correlation spectroscopy NMR techniques. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1292–1305, 2005

Synthesis of novel copoly(ether ether ketones): Property evaluation and microstructure analysis by NMR

Several poly(aryl ether)s have been prepared by the condensation of 1,3‐bis(4‐hydroxy phenyl) benzene with different trifluoromethyl activated bis‐fluoro compounds. IR, 1H and 13C NMR, and elemental analyses have established the resulting polymer structures. The properties of the polymers have been evaluated by DSC, TGA, dynamic mechanical analysis (DMA) and stress–strain analysis. The polymers 1a and 1c showed semi‐crystalline behavior as evident by sharp crystalline melting peaks at 299°C and 330°C along with glass transitions at 202°C and 216°C, respectively. The polymers showed very good thermal stability in air, high modulus, and high tensile strength with low elongation at break.

Vijay Kute

Papers

Polyimides 7: Synthesis, characterization, and properties of novel soluble semifluorinated poly(ether imide)s

Polyimides 6: Synthesis, characterization, and comparison of properties of novel fluorinated poly(ether imides)

Novel Semi‐Fluorinated Poly(ether imide)s Derived From 4‐(p‐Aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl

Synthesis of novel copoly(ether ether ketones): Property evaluation and microstructure analysis by NMR

Synthesis and Characterization of Novel Poly(Arylene Ether)s from 1,3‐bis(4‐Hydroxyphenyl) Benzene