Pendent Trifluoromethyl Research Articles

Double-activated nucleophilic aromatic substitution polymerization by bis-ortho-trifluoromethyl groups to soluble para-poly(biphenylene oxide)

Poly(biphenylene oxide)s (PBPOs) containing two pendent trifluoromethyl groups were synthesized from AB-type monomers, 4ʹ-hydroxy-4-fluoro-3,5-bis(trifluoromethyl)biphenyl and its 3ʹ-hydroxyl isomer. The displacement reaction of fluorine leaving group activated by the two trifluoromethyl groups at the ortho-positions produced high-molecular-weight polymers with Mn up to 101,000 g/mol, indicating the nucleophilic aromatic substitution reaction proceeded effectively. PBPOs with para-, meta-, and mixed ether linkages were obtained and well characterized by FTIR and 1H/19F NMR spectroscopies. All PBPOs were amorphous and soluble in a wide range of organic solvents, and exhibited even more enhanced thermal stability than the previously reported two meta-trifluoromethyl substituted analogues. Increasing the para-linkage fraction in the polymer generally improved solubility and increased Tg in contrast to the meta-trifluoromethyl case, where para-linked polymer was poorly soluble and semicrystalline. This suggests that the ortho-trifluoromethyl substituents are more effective for the synthesis of para-linked PBPOs. They also showed low refractive indices and birefringence values.

Cardo fluorene based semifluorinated co-poly(arylene ether)s: Synthesis, characterization and dielectric properties

Three new co-poly(arylene ether)s (PAE) containing cardo fluorene moiety in the main chain and pendent trifluoromethyl group have been synthesized by one pot high temperature polycondensation reaction using two kinds of bis-hydroxy compound, 9,9-bis(3,5-dimethoxy-4-hydroxyphenyl)fluorene (DMHF), bisphenol A (BPA) and three different bis-fluoro monomers. The structures of the resulting co-PAEs were investigated by FT-IR and NMR spectroscopy. All the polymers showed good solubility in common organic solvents and high weight average molecular weight up to 443,000 g/mol. Flexible, transparent and mechanically strong films were obtained after solution casting from N,N-dimethylacetamide (DMAc). The polymers exhibited reasonably high thermal stability (Td10, in the range of 459–485 °C) and high glass transition temperature (215–228 °C). The PAE membranes also revealed good optical transparency (λcut-off = 350–370 nm) along with very small water absorption (0.38–0.49%) after 72 h immersion in water. Furthermore, the PAE membranes showed low dielectric constants with the values in the range of 2.25–2.42 at room temperature and at 1 MHz frequency, measured from their capacitance.

Comparative investigations on the effects of pendent trifluoromethyl group to the properties of the polyimides containing diphenyl-substituted cyclopentyl Cardo-structure

Two series of Cardo-type polyimides (PIs), fluorinated or nonfluorinated, were prepared from condensation of the fluorinated Cardo-type diamine 1,1-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]cyclopentane (BATFPCP) or the analogous nonfluorinated Cardo-type diamine 1,1-bis[4-(4-aminophenoxy)phenyl]cyclopentane (BAPCP) with four aromatic dianhydrides PMDA, ODPA, BTDA and BPDA, respectively. Both fluorinated and nonfluorinated PIs with Cardo-structure in polymer backbone generally retained good thermal properties comparable to aromatic PIs, with glass transition temperature (Tg) of 227–270°C and 234–340°C, 5% weight loss temperature in nitrogen (air) of 471–483°C (448–474°C) and 472–482°C (464–492°C), respectively. The fluorinated and nonfluorinated PIs with Cardo-structure in the polymer backbone showed tensile strengths of 90.1–101.7MPa and 78.6–99.6MPa, tensile modulus of 1.44–1.83GPa and 1.25–1.50GPa, respectively, also comparable to those of the traditional aromatic PIs. In comparison with nonfluorinated series, the fluorinated PIs possessed better solubility, higher optical transparency and lower water absorption. The fluorinated PIs were readily soluble in a variety of organic solvents, exhibited high optical transparency and light color with the cut off wavelength at 373–424nm and transmittance at 500nm generally higher than 80%, and the water absorptions were measured as low as 0.18–0.93%. Additionally, the fluorinated series showed higher hydrophobicity by water contact angles and water absorption measurements and lower dielectric constant by dynamic dielectric measurements.

Poly(arylene ether)s with trifluoromethyl groups via meta-activated nitro displacement reaction

New poly(arylene ether)s with pendent trifluoromethyl groups were synthesized from 2,2′-bis(trifluoromethyl)-4,4′-dinitro-1,1′-biphenyl with several bisphenols. The nitro leaving group activated by the trifluoromethyl group at meta position was quantitatively displaced with phenolate ions, resulting in high molecular weight polymers. The quantum mechanical calculation of the energy state suggested that the nitro displacement reaction activated by the trifluoromethyl group at meta position is an energetically favorable process. The polymers having weight average molecular weight of 42,100–95,000 g/mol and molecular weight distribution of 2.65–2.95 were obtained. The polymers were amorphous and dissolved in a wide range of organic solvents. Transparent and flexible films were obtained by solution casting. The resulting polymers are thermally stable, and T gs of the polymers are in the range of 176–199 °C depending on their molecular structure. All of the synthesized polymers show refractive indices in the range of 1.592–1.624 with low birefringence below 0.006.

Synthesis of New Poly(biphenylene oxide) with Pendent Trifluoromethyl Group

A new AB type of monomer 4′-fluoro-3,5-dimethyl-3′-trifluoromethyl-biphenyl-4-ol has been synthesized that leads to a new poly(arylene ether) by self polycondensation reaction. The monomer and the polymer have been well characterized by elemental analyses, FT-IR and NMR spectroscopy. Both FT-IR and NMR spectra of the polymers did not show any terminal phenoxy group indicating high conversion. The polymer showed glass transition at 278°C and very good thermal stability in synthetic air. GPC results indicate high molar mass development; Mw = 53200 and MWD = 2.29.

Synthesis and characterization of novel (sulfonated) poly(arylene ether)s with pendent trifluoromethyl groups

This paper reports the synthesis of four different trifluoromethyl-substituted poly(arylene ether)s on the basis of 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF) and various difluoro- or dinitrobiphenyl or terphenyl monomers in the course of a step-growth polycondensation. Besides a comparison between the polymerisability of the different monomer combinations, a main focus of this work lies on the NMR characterization of these poly(arylene ether)s. Poly(arylene ether)s with sufficiently high number average molecular weights were sulfonated by fuming sulfuric acid or chlorosulfonic acid and investigated in terms of membrane properties relevant for fuel cell applications.

New poly(arylene ether)s containing phthalimidine group in the main chain

AbstractFive new poly(arylene ether)s containing phthalimidine group in the main chain and pendent trifluoromethyl group have been prepared by the reaction of 4,4′‐(bis‐4‐fluoro‐3‐trifluoromethylphenyl)benzene (BTF) with bisphenols. Different molar ratios of N‐phenyl‐3,3‐bis(4‐hydroxyphenyl)phthalimidine (PA) and 4,4′‐isopropylidenediphenol (BPA) have been used to generate different copolymers. The polymers obtained by step growth polymerization exhibited weight‐average molecular weight upto 134,000 g/mol with a polydispersity index of 2.1–2.4. The homopolymer from BTF and PA showed very high glass transition temperature of 258°C and outstanding thermal stability upto 536°C for 5% weight loss under nitrogen. The polymers were soluble in a wide range of organic solvents. Transparent thin films of these polymers exhibited tensile strengths upto 65 MPa and elongation at break upto 45% depending on the exact repeat unit structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Highly optically transparent/low color polyimide films prepared from hydroquinone- or resorcinol-based bis(ether anhydride) and trifluoromethyl-containing bis(ether amine)s

Two series of novel polyimides ( 5a– g and 6a– g) containing flexible ether linkages and pendent trifluoromethyl (CF 3) groups were synthesized from 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride ( 3a) and 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride ( 3b) with various CF 3-substituted aromatic bis(ether amine)s ( 4a– g) via ring-opening polyaddition to poly(amic acid)s, followed by thermal or chemical imidization. These polyimides were readily soluble in a variety of organic solvents and could be solution-cast into flexible and tough films. The cast films exhibited high optical transparency and almost no color, with a UV–vis absorption edge of 368–382 nm and a very low b ∗ value (a yellowness index) of 6.2–15.5. They had good thermal stability with glass-transition temperatures of 186–288 °C, and most of them did not show significant decomposition before 500 °C. Moreover, these polyimide films also possessed low dielectric constants of 2.79–3.49 (at 1 MHz) and low water uptakes (<0.65 wt%).

Thermally Stable, Organosoluble, and Colorless Poly(ether imide)s Having Ortho‐Linked Aromatic Units in the Main Chain and Trifluoromethyl Pendent Groups

AbstractSummary: A novel series of aromatic poly(ether imide)s (PEIs) IVa–h containing ortho‐linked aromatic units and pendent trifluoromethyl (CF3) groups were prepared from 2,3‐bis(3,4‐dicarboxyphenoxy)naphthalene dianhydride (I) with various CF3‐substituted aromatic bis(ether amine)s IIa–h via a conventional two‐stage process including ring‐opening polyaddition to form the poly(amic acid)s followed by either chemical or thermal imidization to the PEIs. The inherent viscosities of PEIs IVa–h were in the range of 0.43–0.86 dL · g−1 that corresponded to weight‐average and number‐average molecular weights (by gel permeation chromatography) of 36 000–73 000 and 23 000–51 000, respectively. All the IV series were highly soluble in several organic solvents and could be solution‐cast into transparent, flexible, and strong films. These films were essentially colorless; their cut‐off wavelengths were between 368 and 377 nm and a very low b* value (a yellowness index) ranging from 4.1 to 5.5. They had useful levels of thermal stability associated with moderately high‐glass transition temperatures (208–281 °C), 10% weight‐loss temperatures in excess of 492 °C, and char yields at 800 °C in nitrogen higher than 51%. They also showed low water uptakes of 0.25–0.48% and low dielectric constants of 3.06–3.67 at 10 kHz. For a comparative study, a series of structurally similar, non‐fluorinated PEIs Va–h from dianhydride I and bis(ether amine)s II′a–h were also prepared and characterized.A novel series of aromatic poly(ether imide)s (PEIs)IVa–h.magnified imageA novel series of aromatic poly(ether imide)s (PEIs)IVa–h.

Novel organosoluble and colorless poly(ether imide)s based on 3,3‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]phthalide dianhydride and aromatic bis(ether amine)s bearing pendent trifluoromethyl groups

AbstractA novel series of colorless and highly organosoluble poly(ether imide)s were prepared from 3,3‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]phthalide dianhydride with various fluorinated aromatic bis(ether amine)s via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s followed by cyclodehydration to produce the polymer films. The poly(ether imide)s showed excellent solubility, with most of them dissoluble at a concentration of 10 wt % in amide polar solvents, in ether‐type solvents, and even in chlorinated solvents. Their films had a cutoff wavelength between 358 and 373 nm, and the yellowness index ranged from 3.1 to 9.5. The glass‐transition temperatures of the poly(ether imide) series were recorded between 237 and 297 °C, the decomposition temperatures at 10% weight loss were all above 494 °C, and the residue was more than 54% at 800 °C in nitrogen. These films showed high tensile strength and also were characterized by higher solubility, lighter color, and lower dielectric constants and moisture absorption than an analogous nonfluorinated polyimide series. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3140–3152, 2006

Organo-soluble and Lightly-colored Fluorinated Polyimides Based on 2,2-Bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane Dianhydride and Aromatic Bis(ether amine)s Bearing Pendent Trifluoromethyl Groups

Two series of soluble and light-colored poly(ether imide)s (III and IV) were synthesized from 2,2-bis[4-(3,4-dicarboxyphenoxyl)phenyl]hexafluoropropane dianhydride (I) and various fluorinated and non-fluorinated aromatic diamines (IIa–g and II′a–g) by a conventional two-step procedure that included a ring-opening polyaddition to give poly(amic acid)s, followed by chemical cyclodehydration to poly(ether imide)s. The III series were lighter-colored and higher optical transparency as compared with the non-fluorinated IV series. On comparing the IV series with the common lightly-colored aromatic polyimides (V series) based on 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), the IV series revealed less colored than the V series. This indicated that both the III and IV series were lightly-colored poly(ether imide)s. These polymer films showed the cutoff wavelength in the range of 364–371 nm. The III series showed good solubility in all testing solvents at a concentration of 5–10 wt/v % and most of IV series was soluble. These polymers exhibited glass-transition temperatures in the range of 194–264 °C, and the 10% weight-loss temperatures were higher than 492 °C under either nitrogen or air atmosphere. The III series also showed lower dielectric constants of 3.01–3.65 at 1 MHz and lower moisture absorption of 0.09–0.44 wt % than IV series.

Colorless and high organosoluble polyimides from 2,5-bis(3,4-dicarboxyphenoxy)- t-butylbenzene dianhydride and aromatic bis(ether amine)s bearing pendent trifluoromethyl groups

A series of polyimides III a– h characterized by colorlessness, high transparency, high solubility, and good mechanical property, was synthesized from the aromatic dianhydride, 2,5-bis(3,4-dicarboxyphenoxy)- t-butylbenzene dianhydride (I), and various aromatic diamines ( II a– h ) with pendent trifluoromethyl group via polyaddition, chemical imidization, and direct cast films. The III series showed more colorless than the polyimides ( V and VI series) of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) contained, the VI series was synthesized from the II with 6FDA. These films III had cut-off wavelengths between 371 and 376 nm, as well as b* value (a yellowness index) ranging from 3.0 to 4.7. In fact, it is so far the most colorless aromatic polyimide in our systematical researches. The III series had inherent viscosity ranging from 0.72 to 1.33 dL/g and showed excellent solubility in a variety of organic solvents. They were soluble in a concentration of 5–10% in the amide polar solvent, ether solvent, and chlorinated solvent. These films showed strength tensile of 97–123 MPa, dielectric constants of 2.78–3.28 (1 MHz), and moisture absorptions of 0.11–0.36 wt%. The glass transition temperature of the III series was recorded at 214–259 °C, the 10% weight loss temperature was over 468 °C, and the residue was more than 47% at 800 °C in nitrogen.

Colorless polyimides from 2,3,3′,4′-biphenyltetracarboxylic dianhydride (α-BPDA) and various aromatic bis(ether amine)s bearing pendent trifluoromethyl groups

A series of organosoluble and light-colored polyimides ( III) was prepared from 2,3,3′,4′-biphenyltetracarboxylic dianhydride (α-BPDA) with various fluorinated aromatic bis(ether amine)s via two-step method with thermal or chemical imidization of poly(amic acid)s yielded polyimides. The III series had inherent viscosity of 0.74–1.01 dl/g and showed excellent solubility in a variety of organic solvents. They were soluble in the amide polar solvent, ether-type solvent, and chlorinated solvent. These polyimide films also showed a high optical transparency and less color intensity, with an ultraviolet-visible absorption edge of 369–382 nm and low b * values (a yellowness index) of 5.0–11.7. Glass-transition temperature of the III series was recorded at 244–319 °C and higher than the isomeric polyimides V series. Compared with the nonfluorinated polyimides IV, the III series showed lighter-colored and lower dielectric constants and moisture absorptions. The good tensile properties and excellent thermal properties of the III series were also observed.

Gas permeabilities of novel poly(arylene ether)s with terphenyl unit in the main chain

The gas permeabilities of CO 2, N 2, O 2 and CH 4 through a series of poly(aryl ether)s containing rigid terphenyl units in the main chain and pendent trifluoromethyl groups were determined at four different temperatures, 35, 45, 55, 65 °C and at 1 bar pressure. The effects of structural variations on permeability coefficients and selectivities for the gas pairs O 2/N 2, CO 2/N 2, CO 2/CH 4, CO 2/O 2, O 2/CH 4 and CH 4/N 2 are discussed. The polymers exhibited high permeabilities, but surprisingly low selectivities, considering the rather stiff polymer chains. The temperature dependence permeability/diffusion coefficients enables to calculate the activation energies for the permeation/diffusion process of different gases through these membranes. The gas permeability results were compared with analogous polymer structures containing pyridine and thiophene rings in the polymer backbone. The poly(arylene ether)s with terphenyl units showed higher gas permeabilities and comparable selectivities for a pair of gas in comparison to the analogous polymer with pyridine and thiophene elements.

Novel Poly(arylene ether)s with Pendent Trifluoromethyl Groups

Six novel perfluoroalkyl-activated bishalo monomers 4a,b−6a,b have been synthesized successfully using Pd(0)-catalyzed cross-coupling reaction of 4-chloro- or 4-fluoro-3-trifluoromethylphenylboronic acid with 1,4-dibromobenzene, 2,6-dibromopyridine, and 2,5-dibromothiophene. These monomers were converted to poly(arylene ether)s by nucleophilic displacement of the halogen atoms on the benzene ring with several bisphenols. The products obtained by displacement of the fluorine atoms exhibit weight-average molar masses up to 3.52 × 105 g mol-1 in GPC. Displacement of the chlorine atoms from the analogous monomer structures by bisphenols was not successful in obtaining high molar mass products. These poly(arylene ether)s showed very high thermal stability even up to 536 °C for 5% weight loss in TGA in synthetic air. Comparatively low thermal stability for the thiophene ring containing polymers was attributed to the oxidation of the sulfur atom of the thiophene ring at high temperature in air, which destroyed the aromatic character of the thiophene ring. This was confirmed by investigating the thermal stability of these polymers in an inert environment. The polymers exhibit glass transition temperatures (Tg) up to 234 °C in DSC. The glass transition temperatures taken as peak in tan δ in DMTA measurements are in good agreement with the DSC Tg values. All the polymers are soluble in a wide range of organic solvents, e.g., CHCl3, THF, NMP, and DMF. Transparent thin films of these polymers cast from THF exhibited tensile strengths up to 70 MPa, a modulus of elasticity up to 2.69 GPa, and elongation at break up to 30% depending on their exact repeating unit structures.

Poly(aryl ether thiazole)s with Pendent Trifluoromethyl Groups

A monomer with two 4-(trifluoromethyl)-5-fluoro-substituted thiazole rings was prepared from terephthalic acid dithioamide and hexafluoroacetone. This monomer was converted to poly(aryl ether thiazole)s by nucleophilic displacement of the fluorine atoms on the thiazole rings with bis(phenol)s or silylated bis(phenol)s. The products obtained by the silyl method exhibit molar masses up to M w = 78 500 g.mol -1 . Compared to analogous polymers with oxazole rings in place of the thiazole rings, the thiazole polymers had higher glass transition temperatures and decreased solubilities. This is attributed to the different geometries of the thiazole and oxazole rings. In addition, the decomposition temperatures of the thiazole polymers were at least 100 deg higher than those of the oxazole polymers. This effect is caused by the more pronounced aromatic character of the sulfur heteroaromatic rings as compared to the oxygen-based systems.

Poly(arylether oxazole)s and poly(arylether thiazole)s with pendent trifluoromethyl groups

AbstractBis(oxazolyl)benzenes and bis(thiazolyl)benzenes containing fluorine atoms and trifluoromethyl groups in the heteroaromatic moieties have been synthesized. These compounds can be used as monomers for the preparation of poly(arylether oxazole)s and poly(arylether thiazole)s with pendent trifluoromethyl groups. The high reactivity of the new oxazole monomers is demonstrated by the synthesis of the corresponding poly(arylene ethers) under extremely mild reaction conditions. The polymers have been characterized by spectroscopical methods, DSC, and dynamic thermogravimetry.