Rigid Dianhydride Research Articles

Intrinsically Microporous Polyimides from Norbornyl Bis-benzocyclobutene-Containing Diamines and Rigid Dianhydrides for Membrane-Based Gas Separation

A series of polyimides of intrinsic microporosity (PIM-PIs) were prepared from commercially available rigid dianhydrides (pyromellitic dianhydride (PMDA), cyclo-[2.2.2]oct-7-ene-2-exo,3-exo,5-exo,6-exo-2,3:5,6-dianhydride (BTA), and 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA)) and diamines with norbornyl bis-benzocyclobutene (N2BC) segments (CANAL-2, CANAL-3, and CANAL-4). The physical and gas transport properties of these polymers were systematically investigated. The fractional free volumes (FFV), interchain distances, surface areas, and cumulative micropore volumes of these PIM-PIs were in the range of 0.156–0.185, 0.593–0.619 nm, 422–615 m2 g–1, and 0.059–0.072 cm3 g–1, respectively, showing a general trend of BTA > PMDA > CBDA for certain diamines. Thus, BTA-CANAL-2 concomitantly exhibited higher gas permeability and perm-selectivity relative to its analogues, viz., PMDA-CANAL-2, CBDA-CANAL-2, and 6FDA-CANAL-2 (6FDA: 4,4′-(hexafluoroisopropylidene)diphthalic anhydride). Specifically, it showed H2 permeability of 1685 barrer, H2/CH4 selectivity of 14, and H2/N2 selectivity of 15, which surpassed the 2008 Robeson’s upper bounds. The W-shaped, cage-like architecture of BTA residues imparted the resulting PIM-PIs with both high FFV and high cumulative micropore volumes, which was the reason for their excellent gas separation performance.

Synthesis and Properties of Optically Transparent Fluoro-Containing Polyimide Films with Reduced Linear Coefficients of Thermal Expansion from Organo-Soluble Resins Derived from Aromatic Diamine with Benzanilide Units.

Wholly aromatic polyimide (PI) films with good solution processability, light colors, good optical transparency, high storage modulus, and improved heat resistance were prepared and characterized. For this purpose, a multi-component copolymerization methodology was performed from a fluoro-containing dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), a rigid dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), and a fluoro-containing diamine, 2,2′-bis(trifluoromethyl)-4,4′-bis [4-(4-amino-3-methyl)benzamide]biphenyl (MABTFMB). One homopolymer, FPI-1 (6FDA-MABTFMB), and five copolymers, FPI-2~FPI-6, containing the BPDA units from 10 mol% to 50 mol% in the dianhydride moieties, were prepared, respectively. The derived PI resins showed good solubility in the polar aprotic solvents, such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc). The flexible PI films obtained by the solution casting procedure showed good optical properties with the transmittances higher than 74.0% at the wavelength of 450 nm. The PI films exhibited excellent thermal properties, including 5% weight loss temperatures (T5%) over 510 °C, together with glass transition temperatures (Tg) over 350.0 °C according to the peak temperatures of the loss modulus in dynamical mechanical analysis (DMA) measurements. The FPI-6 film also showed the lowest linear coefficient of thermal expansion (CTE) value of 23.4 × 10−6/K from 50 to 250 °C according to the thermomechanical analysis (TMA) measurements, which was obviously lower than that of FPI-1 (CTE = 30.6 × 10−6/K).

Influence of diamine rigidity and dianhydride rigidity on the microstructure, thermal and mechanical properties of cross-linked polyimide aerogels

Polyimide aerogels (PAs) using different monomers were prepared by cross-linking with a low-cost aminosilane, bis(trimethoxysilylpropyl) amine. The influence of diamine rigidity and dianhydride rigidity on the microstructure, thermal and mechanical properties of PAs were investigated independently. It was found that Young's modulus and yield strength of the PAs increase with the increase of rigidity of diamine or dianhydride. PA prepared with the most rigid dianhydride (pyromellitic dianhydride, PMDA) and diamine (4,4′-oxydianiline, ODA) shows the highest Young's modulus of 45.7 MPa, while that prepared with the most rigid diamine (p-phenylenediamine, PPDA) and dianhydride (biphenyl-3,3′,4,4′-tetracarboxylic dianhydride, BPDA) exhibits the highest yield strength of 2.9 MPa. PAs prepared with more flexible diamines tend to form more disordered microstructure with larger pores and broader pore size distribution. Meanwhile, the thermal conductivity of PAs shows a decreasing tendency with the decrease of diamine rigidity. The lowest thermal conductivity of 0.038 W/(m·K) comes from the sample synthesized using ODA and BPDA. Besides, the initial thermal decomposition temperature depends mainly on the diamine, which illustrates that diamine rigidity has a greater effect on thermal stability than dianhydride rigidity. By contrast, no obvious correlation between the dianhydride rigidity and properties of PAs was observed. The obtained PAs exhibit good application potential for aerospace applications and their properties can be tailored by adjusting the monomer rigidity.

Understanding the Effect of the Dianhydride Structure on the Properties of Semiaromatic Polyimides Containing a Biobased Fatty Diamine.

In this work we report the effect of the hard block dianhydride structure on the overall properties of partially biobased semiaromatic polyimides. For the study, four polyimides were synthesized using aliphatic fatty dimer diamine (DD1) as the soft block and four different commercially available aromatic dianhydrides as the hard block: 4,4′-(4,4′-isopropylidenediphenoxy) bis(phthalic anhydride) (BPADA), 4,4′-oxidiphthalic anhydride (ODPA), 4,4′-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA), and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA). The polymers synthesized were fully organo-soluble thermoplastic branched polyimides with glass transition temperatures close to room temperature. The detailed analysis took into account several aspects of the dianhydrides structure (planarity, rigidity, bridging group between the phtalimides, and electronic properties) and related them to the results obtained by differential scanning calorimetry, rheology, fluorescence and broadband dielectric spectroscopy. Moreover, the effects of physical parameters (crystallization and electronic interactions) on the relaxation behavior are discussed. Despite the presence of the bulky branched soft block given by the dimer diamine, all polyimides showed intermolecular charge transfer complexes, whose extent depends on the electronic properties of the dianhydride hard block. Furthermore, the results showed that polyimides containing flexible and bulky hard blocks turned out fully amorphous while the more rigid dianhydride (BPDA) led to a nanophase separated morphology with low degree of crystallinity resulting in constrained segmental relaxation with high effect on its mechanical response with the annealing time. This work represents the first detailed report on the development and characterization of polyimides based on a biobased fatty dimer diamine. The results highlight the potential of polymer property design by controlled engineering of the aromatic dianhydride blocks.

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.

Advances in the design of co-poly(ether-imide) membranes for CO2 separations. Influence of aromatic rigidity on crystallinity, phase segregation and gas transport

In our previous works, it was observed a clear relationship between the structure and the properties for different copoly(ether-imide)s, besides a good relation was found between SAXS characterization and permeability results. Here, a series of aliphatic aromatic copoly(ether-imide)s, based on an aromatic diamine (ODA), a diamine terminated poly(ethylene oxide) (PEO2000) of a molecular weight of 2000g/mol and different aromatic dianhydrides (BPDA, BKDA (or BTDA) and PMDA) has been synthesized and characterized.The permeability for O2, N2, CO2 and CH4, increased with the rigidity of the monomers (BKDA<BPDA<PMDA), with the amount of PEO2000 in the copolymers, as well as with the increase in the temperature of treatment of the films. In this case, it was observed that when the proportion of PEO in the copolymer exceeded 50%, the permeability was similar for all samples, and the aromatic portion had no significant influence.Attending to glass transition temperature, Tg, of the aliphatic part, to its melting temperature, Tm, and to its crystallinity, segregation was better for more rigid dianhydrides at lower temperatures of treatment. Higher dianhydride rigidity produced better mechanical properties that were good but decreased a little bit when the percentage of PEO in the samples increased.Good permselectivity compromises were attained for the CO2/N2 separation. This work gives indications on how to design advanced materials for this separation with the increasing possibilities of controlled structure and properties.

Chemical structure-transport behavior relationship for polyimides and copolyimides based on rigid and flexible dianhydrides

Gas-separation membrane characteristics of a number of new polyimides containing common dianhydride and diamine moieties, including two copolymers of the regular structure, have been investigated. The densities of polymer films have been measured, and the permeability and diffusion coefficients of H2, CO, CO2, and CH4 gases have been estimated. The values of free volume, solubility coefficients of these gases, and selectivities of gas separation have been determined. The transport parameters of polyimides depend on the combination of rigid and flexible dianhydride and diamine fragments. The combination of rigid dianhydride fragments with rigid diamine moieties and of flexible dianhydride fragments with symmetric flexible diamine moieties is the most promising for membrane applications.

Synthesis and properties of novel aromatic poly(ester-imide)s bearing 1,5-bis(benzoyloxy)naphthalene units

Two series of new aromatic poly(ester-imide)s were prepared from 1,5-bis(4-aminobenzoyloxy)naphthalene ( p- 1) and 1,5-bis(3-aminobenzoyloxy)naphthalene ( m- 1), respectively, with six commercially available aromatic tetracarboxylic dianhydrides via a conventional two-stage synthesis that included ring-opening polyaddition to give poly(amic acid)s followed by chemical imidization to polyimides. The intermediate poly(amic acid)s obtained in the first stage had inherent viscosities of 0.41–0.84 and 0.66–1.37 dl/g, respectively. All the para-series and most of the meta-series poly(ester-imide)s were semicrystalline and showed less solubility. Two of the meta-series poly(ester-imide)s derived from less rigid dianhydrides were amorphous and readily soluble in polar aprotic solvents, and they could be solution-cast into transparent and tough films with good mechanical properties. The meta-series polymers derived from rigid dianhydrides were generally semicrystalline and showed less solubility. Except for one example, the meta-series poly(ester-imide)s displayed discernible T gs in the range 239–273 °C by DSC. All of these two series poly(ester-imide)s did not show significant decomposition below 450 °C in nitrogen or in air.

Synthesis and Properties of New Aromatic Polyamides and Polyimides based on 1,4-Bis[N-(4-aminobenzoyl)-N-phenyl]phenylenediamine

A new N-phenylated amide (N-phenylamide) unit-containing aromatic diamine, 1,4-bis[N-(4-aminobenzoyl)-N-phenyl]phenylenediamine, was prepared by the condensation of NŃ-diphenyl-1,4-phenylenediamine with 4-nitrobenzoyl chloride, followed by catalytic reduction. Two series of aromatic poly(N-phenylamide-imide)s and poly(N-phenylamide-amide)s with inherent viscosities of 0.25-0.42 and 0.25-0.54 dL g-1 were prepared by a conventional two-stage method and the direct phosphorylation polycondensation, respectively, from the diamine with various aromatic dianhydrides and aromatic dicarboxylic acids. Some polymers based on rigid dianhydrides and diacids were semi-crystalline and insoluble in organic solvents. The other polymers were amorphous and organosoluble and could afford freestanding or tough films via solution casting. These polyimides and polyamides had glass transition temperatures in the range of 248-267 and 177-198°C, respectively. Decomposition temperatures of the polyimides for 10% weight loss all occurred above 470°C in both nitrogen and air atmospheres.

Synthesis and Properties of Novel Aromatic Poly(esterimide)s Bearing Naphthalene-2,7-Diyl Units

Two series of 2,7-naphthalenediyl units-containing homoand copoly(ester imide)s were prepared from 2,7-bis(4-aminobenzoyloxy)naphthalene and 2,7-bis(3-aminobenzoyloxy)naphthalene, respectively, with six commercially available aromatic tetracarboxylic dianhydrides and their mixtures via a conventional two-stage synthesis that included ring-opening polyaddition to give poly(amic acid)s followed by chemical imidization to polyimides. The intermediate poly(amic acid)s obtained in the first stage had inherent viscosities of 0.59∼1.15 and 0.51∼1.20 dL g-1, respectively. Some of the poly(ester imide)s derived from less rigid dianhydrides had excellent solubility in polar aprotic solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide and could be solution-cast into transparent, flexible, and tough films. The poly(ester imide)s derived from rigid dianhydrides such as pyromellitic dianhydride (PMDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) were semicrystalline and showed less solubility. Except for some examples, most of the poly(ester imide)s displayed discernible glass-transition temperatures ( Tgs) between 233 and 295°C in the differential scanning calorimetry traces. These poly(ester imide)s showed insignificant decomposition below 450°C in nitrogen or air. The investigation of the thermal decomposition of the poly(ester imide)s using pyrolysis-gas chromatography/mass spectrometry (pyrolysis-GC/MS) indicated that a dramatic breakage of the ester linkages occurred at around 450°C, which initiated the polymer chain scission.

High‐performance polymer films. III. Preparation and characterization

AbstractA series of polyimide and copolyimide films were prepared by film casting, drying, and thermal imidization from the respective precursor poly(amic acid) (PAA) and copoly(amic acid) solutions derived from two dianhydrides, pyromellitic dianhydride (PMDA) and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), and two diamines, 4,4′‐oxydianiline (ODA) and a proprietary aromatic diamine (PD) as monomers. Depending on the solution's inherent viscosity value (molecular weight) and the nature of the polymer chains (derived from rigid or flexible monomers), precursor poly(amic acid) and copoly(amic acid) solution concentrations of 8–12% (w/w) were found to be suitable for the preparation of good quality polyimide/copolyimide films. The recovery of film toughness and creasability from the brittleness at the intermediate temperature of the cure cycle depended not only on the molecular weight of the precursor poly(amic acids)/copoly(amic acids) but also on their chain flexibility. The poly(amic acid) derived from both rigid dianhydride and diamine practically gave rise to a brittle film of polyimide even after curing to 360°C. The resulting polyimide and copolyimide films were compared with Du Pont's Kapton H film. The density of the films was in the range 1.39–1.42 g/cm3. The thickness of most of the films was in the range 20–30 μm. The HPF 3 film, based on PMDA–PD, appeared to be highly colored (reddish brown), and the HPF 2 film, based on BTDA–ODA, had the lightest yellow coloring among the films in this investigation, including Kapton H film. HPF 2, HPF 6, and HPF 8 films were more amorphous than the other films. © 2001 John Wiley &amp; Sons, Inc. J Appl Polym Sci 82: 976–988, 2001

Synthesis and characterization of new soluble polyimides derived from 2,2-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]propane

A diamine monomer containing isopropylidene and methyl substituted arylene ether, 2,2-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]propane (TBAPP), was prepared in two steps. The monomer was reacted with six different aromatic tetracarboxylic dianhydrides in N.N-dimethylacetamide (DMAc) to obtain the corresponding new polyimides via the poly(amic acid) precursors and thermal or chemical imidization. The poly(amic acid)s obtained had inherent viscosities ranging from 1.38-2.10 dL . g 1 . All the poly-(amic acid)s could be cast from DMAc solutions and thermally converted into transparent, flexible, and tough polyimide films. The polyimide films had a tensile strength in the range from 52-95 MPa, an elongation at break within a range of 4-8%, and a tensile modulus in the range from 1.60-2.09 GPa. All polyimides were amorphous. The polyimides derived from diamine TBAPP had excellent solubility in various solvents except for those derived from rigid dianhydrides such as pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride. These polyimides showed glass transition temperatures between 249-293 C and decomposition temperature at 10% mass loss temperatures ranging from 460-485°C in nitrogen.