Dianhydride Monomers Research Articles

Highly permeable polyimide membranes with a structural pyrene containing tert-butyl groups: Synthesis, characterization and gas transport

Three new polyimides with high gas permeability based on a new dianhydride 3,8-di(4-tertbutylphenyl)pyrene-1,2,6,7-tetracarboxylic DPt, containing tert-butyl moieties are reported. Chemical structures of the resulting dianhydride monomer and polyimides were confirmed by FTIR and 1H-NMR. All polyimides show high thermal stability with onset decomposition temperatures above 490 °C, and glass transition temperatures above 340 °C. The incorporation of a pendant tert-butyl group into the polymer provided high gas permeability with moderated selectivity. The polyimide formed from DPt and 2,4,6-trimethyl-m-phenylenediamine, DPt-TMPD, showed 2035 Barrer CO2 permeability which could be attributed to its inefficient chain packing from the incorporation of tert-butyl groups that increased the polymer FFV. The obtained gas permeability coefficients and gas selectivities are similar to those reported for PIM-PI polymers.

Polyimides as cathodic materials in lithium batteries: Effect of the chemical structure of the diamine monomer

ABSTRACTPolyimides are being investigated as alternative, environmentally friendly and safe organic electrode materials for lithium and sodium batteries. However, further improvements need the proper chemical design of these polymers. In this paper, the effect of chemical structure of polyimides on their performance as cathodic materials in lithium batteries was investigated in detail. More in particular, we studied polyimides based on seven different diamine monomers in combination with best performing naphthalenic dianhydride monomer. The first set included the so‐called cardo diamines possessing additional redox‐active carbonyl group with the goal to enhance the theoretical capacity of the polymer. Second, several aromatic diamines including additional functionalities such as cyclic amides, anthrone, or quinolidinium groups were investigated. Finally, aliphatic diamines, containing oxyethylene moieties and thus capable to increase the ionic conductivity of the resulting polymer system, were explored. Among the different polyimides, the “cardo” one based on naphthalenic dianhydride and aromatic aniline phthalein with an additional carbonyl group showed the best results in terms of battery performance. Such polyimide was capable to deliver up to 130 mAhg−1 specific capacity (87% of the theoretical value) at 25 °C and at a current density of 250 mAg−1 during 100 charge/discharge cycles. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 714–723

Synthesis and properties of soluble aromatic polyimides from novel 4,5-diazafluorene-containing dianhydride

A dianhydride monomer containing 4,5-diazofluorene was synthesized, and the corresponding organo-soluble polyimides exhibited good comprehensive properties.

Novel organosoluble and thermally stable polyetherimides based on a new dianhydride monomer 2,6-bis-(isobenzofuran-1,3-dione-5-yl)pyridine (BIDP)

ABSTRACTA series of organosoluble and thermally stable polyetherimides (PEIs) containing pyridine moieties and flexible ether linkages are synthesized based on a new aromatic dianhydride, 2,6-bis-(isobenzofuran-1,3-dione-5-yl)pyridine (BIDP). The prepared polymers are soluble in common aprotic solvents such as DMF, DMSO, NMP and DMAc at room temperature. Thermal behavior of the PEIs is studied by thermogravimetric analysis/dynamic thermal analysis (TGA-DTA). The inherent viscosities of the PEI solutions are in the range of 0.61–0.70 dL/g (in DMSO with a concentration of 0.25 g/dL at 25±0.5°C). The metal ion uptake capacity of PEI-4 for Co(II) removal from aqueous solutions is shown to be remarkably higher than that of the polyimide (PI) with a similar structure reported earlier.

Bio-Based Poly(Ether Imide)s from Isohexide-Derived Isomeric Dianhydrides.

In this work, four isohexide-derived isomeric dianhydrides were synthesized through a four-step procedure using isohexide and chloro-N-phenylphthalimides as the starting materials. The one-step solution polymerization of these dianhydrides with petroleum- or bio-based diamines enabled the synthesis of poly(ether imide)s (PEIs), which had viscosities of 0.41 to 2.40 dL∙g−1. The isohexide-derived PEIs were characterized based upon their solubility and their thermal, mechanical, and optical properties. The results showed that most of the isohexide-derived PEIs possessed comparable glass transition temperatures (Tg), tensile strengths, and moduli to petroleum-based PEIs. However, the thermo-oxidative stability of the PEIs was found to be lower than that of the common petroleum-based PEIs. Moreover, the PEIs displayed good optical activity, which originated from their unique chiral isohexide moieties. The isomeric effects of dianhydride monomers on the properties of the resulting PEIs were comparatively studied. The results suggested that the corresponding 4,4′-linked PEIs possessed lower Tg, higher mechanical properties, and higher specific rotations compared to 3,3′-linked polymers. Meanwhile, the polyimides with isomannide residue displayed higher Tg and more specific rotations than the corresponding polymers with isosorbide residue. These results contributed to more restricted rotations of phthalimide segments in 3,3′-linked or isomannide containing polyimides.

Molecular design of some semi-alicyclic polyimides as a route to improve refraction and dielectric properties for liquid crystal display applications

The study establishes an adequate monomer combination for achieving the best balance of properties required in obtaining polyimide alignment layers for display devices. The molecular design of some aliphatic/aromatic polyimides was performed by using dianhydride monomers with distinct configurations in terms of rigidity, size, and symmetry. The polyimides based on semi-flexible and nonsymmetric dianhydride moieties present lower refractive index and dielectric constant (<3) than those obtained from symmetric and rigid dianhydride units. This determines faster traveling of visible and microwave radiations as required for liquid crystal alignment purposes. The interactions of samples with the N-(4-Methoxybenzylidene)-4-butylaniline, cyanobiphenyl, and 4-pentyl-4-cyanobiphenyl nematics were assessed. The analyzed polyimides have higher surface tensions than the ones of the liquid crystals, determining a parallel arrangement of the nematic molecules. As the dispersive interactions at the polymer surface are lower, the work of spreading is higher as a result of improved adhesion of liquid crystal with the polyimide alignment layer. The sample containing rigid, symmetric, noncoplanar dianhydride units (PI.4) and the one based on semi-flexible, nonsymmetric dianhydride moieties are the most transparent for visible and microwave radiations, allowing low cohesion interaction at interface with nematics. These aspects recommend the two studied polyimides as candidates for alignment layers.

A hierarchically porous polyimide composite prepared by one-step condensation reaction inside a sponge for heterogeneous catalysis

A compressible polyimide composite having metal binding sites was prepared by in situ polymerization inside a melamine sponge. 1,3,5-Tris(4-aminophenyl)benzene and pyromellitic dianhydride were used as a triamine and a dianhydride monomer, respectively, to construct the microporous framework, and 5-amino-1,10-phenanthroline was used as a functional monomer. The microporous polyimide containing phenanthroline groups (MPI-Phen) was obtained as insoluble powders. However, when the polymerization was carried out in the melamine sponge, MPI-Phen formed a coating layer on the sponge skeletons. The melamine sponge/microporous polyimide composite (MS/MPI-Phen) had an open cellular structure with a hierarchical porosity composed of macropores between the sponge skeletons and meso- and micropores of the MPI-Phen coating. It showed the higher compressive strength than the melamine sponge, indicating the reinforcement by the microporous polymer. The BET surface areas of MPI-Phen and MS/MPI-Phen were 723 m2g-1 and 524 m2g-1, respectively. Pd(II) ions were coordinated with the phenanthroline groups of MS/MPI-Phen for heterogeneous catalysis. The catalytic activity of MS/MPI-Phen-Pd was evaluated for the Suzuki coupling reaction between bromobenzene and phenylboronic acid.

From a flexible hyperbranched polyimide to a microporous polyimide network: Microporous architecture and carbon dioxide adsorption

A dianhydride monomer 2, 5-bis(3, 4-dicarboxyphenoxy)-4′-phenylethynyl biphenyl (PEPHQDA) containing a chain extendable phenylethynyl pendant group has been successfully synthesized via successive nucleophilic substitution, Sonogashira cross-coupling, hydrolysis and dehydration reactions. A flexible microporous polyimide network has been prepared based on the use of triamine (TAPOB), affording hyperbranched polyimide, followed by the curing of phenylethynyl groups to give network structure. Specifically microporous features such as a well-defined surface morphology, microporous structure and nanometer-sized pore channels have been introduced to the flexible polyimide networks through this two-step pathway. This network exhibit a BET surface area (322 m2 g−1) as well as a comparable CO2 uptake (1.25 mmol g−1 at 273 K and 1 bar) and enthalpy of adsorption (30.3 kJ mol−1) to that of other microporous polyimides derived from rigid tridimensional monomers.

Synthesis and memory characteristics of highly organo‐soluble hyperbranched polyimides with various electron acceptors

ABSTRACTA series of hyperbranched polyimides (HBPIs) were synthesized by reacting a triamine monomer N,N′,N″‐tris(4‐methoxyphenyl)‐N,N′,N″‐tris(4‐phenylamino)−1,3,5‐benzenetriamine with various dianhydrides such as oxydiphthalic dianhydride (ODPA), 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA), 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), and pyromellitic dianhydride (PMDA). The hyperbranched polyimide (6FHBPI) using 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) as dianhydride monomer was also added into the discussion. All the hyperbranched polyimides exhibited excellent organo‐solubility and high thermal stability. Memory devices with a sandwiched structure of indium tin oxide (ITO)/HBPI/Al were constructed by using these HBPIs as the active layers. All these HBPIs based memory devices exhibited favorable memory performances, with switching voltages between −1.3 V and −2.5 V, ON/OFF current ratios up to 107 and retention times long to 104 s. Tunable memory characteristics from electrical insulator to volatile memory, and then to nonvolatile memory were obtained by adjusting the electron acceptors of these HBPIs. Molecular simulation results suggested that the electron affinity and the dipole moment of these HBPIs were responsible for the conversion of the memory characteristics. With the electron affinity and dipole moment of these HBPIs increasing, the memory characteristics turned from volatile to nonvolatile. The present study suggested that tunable memory performance could be achieved through adjusting the acceptor moieties of the hyperbranched polyimides. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2281–2288

Aromatic polyimides containing cyclopropylamide fragment as pendant group. A study of the balance between solubility and structural rigidity

Aromatic polyimides (PIs) containing a cyclopropylamide moiety as bulky polar pendant group were prepared in high yield and were structurally characterized. Polyimides containing 4,4’-hexafluoroisopropyliden diphthalic anhydride and bis(3,4-dicarboxyphenyl)dimethylsilane anhydride were soluble in aprotic polar organic solvents, while those PI derived from benzophenone-3,3′,4,4′-tetracarboxylic dianhydride with a keto central unit was insoluble. The relationship between bulky pendant group and the nature of the central moiety of the dianhydride monomer respect to the thermal properties of the PIs was studied. All PIs were thermally stable showing thermal decomposition temperature with the 10% weight loss (TDT10%) between 425-480 oC. The glass transition temperature (T g) values range between 265 and 315 °C. Mechanical properties from films of a selected PI were tested too.

Synthesis and characterization of low-CTE polyimide films containing trifluoromethyl groups with water-repellant characteristics

A novel fluorinated ester-bridged aromatic diamine, bis(2-trifluoromethyl-4-aminophenyl)terephthalate (CF3-BPTP) was synthesized, which was employed to prepare a series of fluorinated ester-bridged polyimide (PFEI) films with controlled ester-bridged segments and fluorine contents in the polymer backbone. The PFEI films were prepared by copolymerization of biphenyl tetracarboxylic dianhydride as aromatic dianhydride monomer and the aromatic diamine monomer mixture consisting of p-phenylenediamine and different amounts of CF3-BPTP. Experimental results indicated that the films’ water uptakes (Wus) reduced with increasing of the CF3 groups loadings in the ester-bridged polyimide backbones while keeping the films with low enough coefficient of thermal expansion (CTE). By controlling CF3 group loadings, polyimide films with desirable combination of thermal, mechanical, and dielectric properties for application in high density and thinner flexible printed circuits (FPCs) have been obtained. Thus, polyimide films with CTE of ≤20 × 10−6 1/K (ppm/K) at 50–200°C, glass transition temperature of ≥310°C, Young’s modulus of ≥6.0 GPa, Wu of as low as 0.7 wt%, dielectric constant ( ε) of 3.3 have been obtained. The two-layer flexible copper clad laminate prepared by coating the polyimide precursor resin poly(amid acid) solution on the surface of copper foil followed by thermal imidization at elevated temperature did not show apparent curling due to its closed CTE value.

Pyrolysis of polyimide membranes from the same dianhydride monomer and different diamines to form carbon membranes

Polyimide membranes were synthesized by the polymerization of five diamines,p-phenylenediamine(PPD),2,3,5,6—tetramethyl-1,4-phenylenediamine(TMPPD),4,4'-oxydianiline(ODA),4,4'-(4,4'-isopropylidenediphenyl-1,1'-diyldioxy) dianiline(BAPP) and 4,4'-(hexafluoroisopropylidene) bis(p-phenyleneoxy) dianiline(BDAF),and the same dianhydride monomer,1,2,4,5-benzenetetracarboxylic anhydride(PMDA).The chemical structures of the membranes pyrolyzed at different temperatures were investigated by TGA,TG-MS,FT-IR and XPS.Results indicate that there are five stages during pyrolysis:(a) the removal of the solvents,adsorbed oxygen and water,(b) imidization,(c) cross-linking and carbonization,which are accompanied by main chain breaking,(d) deoxygenation and dehydrogenation,(e) aromatization and turbostratic carbon formation.The chemical structure of the precursor is the main factor that causes the great differences in chemical structures during pyrolysis.Imidization in the pyrolysis of the PPD-PMDA and TMPPD-PMDA occurs at higher temperatures than those for ODA-PMDA,BDAF-PMDA and BAPPPMDA.The order of temperatures for the release of CH_4,CO_2 and C_6H_6 during the pyrolysis is ODA-PMDA BDAF-PMDA BAPP-PMDA.Elemental F in the BDAF-PMDA disappears after pyrolysis at 700 ℃.The chemical structures of the polyimides have a great influence on the micro structures of the carbon membranes obtained.

High-efficiency fluorescent polyimides based on locally excited triarylamine-containing dianhydride moieties

Three fluorescent polyimides (PIs) were readily synthesized from the polycondensation of triarylamine-based tetracarboxylic dianhydride monomers with aliphatic diamine. The PL intensity of solid films and nanofibers revealed high PL quantum yields of up to 32% and 35%, respectively.

Highly soluble and thermally stable copolyimides modified with trifluoromethyl and siloxane

ABSTRACTA series of highly soluble aromatic polyimides with excellent thermal properties were fabricated by traditional two‐step polycondensation reaction of dianhydride monomer 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthalic anhydride) or 4,4‐(hexafluoroisopropylidene)diphthalic anhydride with diamine monomer 1,3‐bis(4‐aminophenoxy)benzene or 1,3‐bis(3‐aminopropyl) tetramethyldisiloxane in N,N‐dimethylacetylamide solvent. Results revealed that copolyimide of PI‐4 containing trifluoromethyl and tetramethyldisiloxane possessed excellent solubility and remarkable thermal properties. PI‐4 could dissolve well in common low boiling point solvents such as THF of up to 80 mg/mL and acetone of 40 mg/mL. Moreover, the 10% weight loss temperature of the PI‐4 was 539°C and the Tg value of the PI‐4 was 311°C. PI‐4 might be easily cast into flexible and tough films applied in optoelectronic devices. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41713.

Polyimides based on 3,5-diaminobenzonitrile

A series of polyimides (PIs) was synthesized by reacting a nitrile-containing aromatic diamine, 3,5-diaminobenzonitrile, with various dianhydrides to yield poly(amic acid)s that were then cyclized to yield PIs by a thermal imidization method. The samples were characterized using thermal analysis, tensile testing, optical transparency analysis, and gas permeability analysis. The cast films exhibited good thermal stability with glass transition temperatures of 204–243°C and none exhibited significant decomposition at temperatures below 480°C. These PI films showed coefficient of thermal expansion values in the range 41.68–106.16 ppm/°C. The oxygen transmission rate values of the films containing various dianhydride monomers were in the range 0.93–27.40 cc m−2 day−1. The PI films containing various dianhydride monomers showed tensile strengths of 47–128 MPa, initial moduli of 2.16–3.23, and elongations at break of 1–7%. Moreover, the PI films possessed a transmittance of 58–82% at 500 nm and had a yellowish color with a yellow index of 12.17–59.61.

Synthesis and characterization of pyrimidine-containing hyperbranched polyimides

We reported the design, synthesis, and properties of two series of polyimides based on pyrimidine nuclei with adjusted monomers’ molar ratios, using 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) as dianhydride monomer, 2,4,6-triaminopyrimidine (TAP), and 4,4′-diaminodiphenyl ether (ODA) as amine monomers. Nuclear magnetic resonance spectroscopy (1H NMR) was used for chemical structural characterization, and the results indicated the various forms of TAP and branched structure units in the obtained polyimides. The morphology and structures of the polyimides were evaluated by X-ray diffraction patterns. The results suggested that all the polyimides, except co-HBPI-3, were hardly crystallized. Most of the resulting polyimides possessed excellent solubility in polar aprotic solvents. The thermogravimetric analysis results showed that the polyimides obtained by copolymerizing with ODA exhibited better thermal stability; and incorporating moderate amount of ODA was helpful for imidization.

Highly fluorinated polyimide blends – Insights into physico-chemical characterization

A thorough study on the physico-chemical properties of novel blends of fluorinated aromatic polyimides prepared on the basis of the similarity of dianhydride monomer units was performed. High-temperature solution polycondensation reactions resulted in high molecular weights polyimides further used as blend components. The blend films and coatings were rootedly characterized by various methods, including FTIR, DSC, thermal stability, UV–Vis and fluorescence spectroscopy, with emphasis on the miscibility behaviour. They exhibited high thermal stability and unique glass transition temperature, a critical evidence of the blends homogeneity. The presence of charge transfer interactions between neighbour polyimide chains was comprehended by UV–Vis and fluorescence spectroscopy, and discussed in correlation with chemical structures. The hydrophobic blend films showed a porous structure or an interlamellar or interfibrillar segregated morphology, good mechanical and optical properties with high transparency. Furthermore, new insights into their physico-chemical behaviour induced by the trifluoromethyl group or other structural features are discussed.

Melem: A metal-free unit for photocatalytic hydrogen evolution

Melem, the building unit of g-C3N4, is reported for the first time as a metal-free photocatalyst for hydrogen evolution from methanol aqueous solution. Melem is synthesized via a facile thermal condensation of melamine at 425 °C. Its chemical structure is verified by the combination of Fourier transform infrared spectroscopy (FTIR), solid-state 13C nuclear magnetic resonance (NMR) and elemental analysis. Density functional theory (DFT) calculations reveal that melem possesses frontier orbitals quite similar to those of g-C3N4. By conjugating melem with dianhydride monomer, an extended polyimide network with greatly enhanced visible-light absorption is formed. Consequently, the visible-light activity for hydrogen evolution is enhanced by six times and reaches to a rate of 13.1 μmol/h. This work may open up new opportunity to develop efficient metal-free photocatalysts based on melem unit.

Impact of Backbone Rigidity on the Photomechanical Response of Glassy, Azobenzene-Functionalized Polyimides

Azobenzene-functionalized polyimide materials can directly transduce light into mechanical force. Here, we examine the impact of polymer backbone rigidity on the photomechanical response in a series of linear, azobenzene-functionalized polymers. The rigidity of the backbone was varied by the polymerization of five dianhydride monomers with a newly synthesized diamine (azoBPA-diamine). The azobenzene-functionalized linear polymers exhibit glass transition temperatures (Tg) ranging from 276 to 307 °C and maintain excellent thermal stability. The photomechanical response of these materials was characterized by photoinduced cantilever bending as well as direct measurement of photogenerated stress upon exposure to linearly polarized, 445 nm light. Increasing the rigidity of the polymer backbone increases the magnitude of stress that is generated but decreases the angle of cantilever deflection.

Low dielectric and thermally stable hybrid ternary composites of hyperbranched and linear polyimides with SiO2

A hydroxyl-terminated hyperbranched polyimide was synthesized via the A2 + B3 reaction between dianhydride and triamine monomers. The hydroxyl groups at the peripheral positions were then introduced by modification of the anhydride end groups via a reaction with 4-aminophenol. Based on the hydroxyl-terminated hyperbranched polyimide, HBPIBPADA-TAP(OH), we successfully fabricated hybrid ternary composites, which were comprised of a linear polyimide (PI6FDA-APB), HBPIBPADA-TAP(OH), and an inorganic SiO2 component. The material was designed to satisfy the requirement for cutting-edge insulators with a low dielectric constant and a high thermal stability. Because of the appropriate choice of the hybrid ternary composite systems with HBPIBPADA-TAP(OH) and inorganic silica, it is sensible to improve the dielectric properties and thermal resistant properties of unary systems or improve the disadvantages of the dielectric and optical properties of binary systems. For an optimized composition, the dielectric constant (Dk) of the PI6FDA-APB–HBPIBPADA-TAP(OH)-30%–SiO2-20% composite reaches the lowest value of 2.24 at 100 kHz. Research also showed that the optical transparency is significantly improved with the increase of the HBPIBPADA-TAP(OH) content in the composite. Compared with the binary linear PI 6FDA-APB–SiO2 composite, the transmittance increases from 1% to 75% at the wavelength of 450 nm. The incorporation of SiO2 can preserve the good thermal properties of the hybrid composites containing HBPIBPADA-TAP(OH). By adding 10% of HBPIBPADA-TAP(OH) to the PI6FDA-APB–SiO2-20% system, the coefficient of thermal expansion of the hybrid ternary composite is 20.9 ppm °C−1 in the temperature range from 100 to 150 °C, which is significantly lower than that of the linear polyimide (37.1 ppm °C−1 for PI6FDA-APB). Because of these optimized properties, hybrid ternary composites have the potential for use in applications in the micro-electronic insulator fields, such as interlayer dielectrics of advanced electronic devices.