Processable Aromatic Polyimides

Highly Self-Healable Polymeric Coating Materials Based on Charge Transfer Complex Interactions with Outstanding Weatherability

In this study, we prepare highly self-healable polymeric coating materials using charge transfer complex (CTC) interactions. The resulting coating materials demonstrate outstanding thermal stability (1 wt% loss thermal decomposition temperature at 420 °C), rapid self-healing kinetics (in 5 min), and high self-healing efficiency (over 99%), which is facilitated by CTC-induced multiple interactions between the polymeric chains. In addition, these materials exhibit excellent optical properties, including transmittance over 91% and yellow index (YI) below 2, and show enhanced weatherability with a ΔYI value below 0.5 after exposure to UV light for 72 h. Furthermore, the self-healable coating materials developed in this study show outstanding mechanical properties by overcoming the limitations of conventional self-healing materials.

Isomeric Aromatic Polyimides Containing Biphenyl Moieties for Gas Separation Applications

An optimized synthesis of the monomer 2,2′3,3′-biphenyltetracarboxylic dianhydride, iBPDA, was performed to obtain high molecular weight polymers. This monomer has a contorted structure that produces a non-linear shape, hindering the packing of the polymer chain. Aromatic polyimides of high molecular weight were obtained by reaction with the commercial diamine 2,2-bis(4-aminophenyl) hexafluoropropane, 6FpDA, which is a very common monomer in gas separation applications. This diamine has hexafluoroisopropylidine groups which introduce rigidity in the chains, hindering efficient packing. The thermal treatment of the polymers processed as dense membranes had two targets: on the one hand, to achieve the complete elimination of the solvent used, which could remain occluded in the polymeric matrix, and on the other hand to ensure the complete cycloimidization of the polymer. A thermal treatment exceeding the glass transition temperature was performed to ensure the maximum degree of imidization at 350 °C. The good mechanical properties of these materials allow for their use in high-pressure gas purification applications. Moreover, models of the polymers exhibited an Arrhenius-like behavior characteristic of secondary relaxations, normally associated with local motions of the molecular chain. The gas productivity of these membranes was high.

Growth manner of rod-shaped ZnO crystals at low temperature without any seed/buffer layer on a polyimide film

Recently, we fabricated a rod-shaped ZnO crystal layer directly on a polyimide substrate without any intermediate layer. In this study, we aimed to understand its fabrication mechanism.

Soluble and transparent polyimides with high Tgs from a new semi-aliphatic diamine with cyclohexyl and ortho-methyl groups

Herein a semi-aliphatic diamine 4,4′-(cyclohexylmethylene)bis(2-methylaniline) (CHMBMA) with a pendant cyclohexyl and two ortho-substituted methyl groups is synthesized from o-toluidine and cyclohexanecarbaldehyde by Mannich and rearrangement reactions. Then CHMBMA is polycondensed with five commercial aromatic dianhydrides by the high-temperature one-step method with the thermal imidization to produce a series of polyimides (PIs, PI-H(1–5)). The weight-averaged molecular weights ( M ws) of PI-H(1–5) are in the range from 9.08 × 104 to 27.48 × 104 g mol−1 with the polydispersity indices (PDI) from 3.29 to 6.13 by gel permeation chromatography (GPC) measurement. They are soluble in common organic solvents (such as THF, CHCl3 etc.) and can form transparent, tough films with light-color (Thickness: 20–26 μm) by the solution-casting method. The light transmittance of them is above 80% in the visible range from 400 to 760 nm. They exhibit excellent mechanical properties with tensile strength from 72.2 to 97.06 MPa and tensile modulus from 0.9 to 1.9 GPa. Furthermore, they also display low water absorption rates (<2.5%), good thermal stability (5% weight loss temperatures ( T 5%) in the range from 466 to 480°C under N2 atmosphere and high glass transition temperatures ( T gs ≥ 319°C). As comparison, we also synthesize these PIs (PI-L(1–5)) by the low-temperature two-step method with the chemical imidization. The M ws of PI-L(1–5) are lower than those of PI-H(1–5), but the film color of PI-L(1–5) is relatively lighter than the corresponding one of PI-H(1–5). In summary, the introduction of cyclohexyl and ortho-substituted methyl groups into the backbone can improve the solubility of PIs and the transparency of their corresponding films without reducing their T gs.

Synthesis of Novel Thermostable Polyamideimides from Bis(2-aminoethyl)terephthalamide and Dianhydrides

Bis(2-aminoethyl)terephthalamide, an amide-containing diamine, was obtained from the aminolysis of waste poly(ethylene terephthalate) bottles. This diamine reacts with various aromatic dianhydrides to form novel polyamideimides (PAIs). The formation of amic acid or ammonium carboxylate salt intermediates depends strongly on the substituents of the dianhydrides. The electron-withdrawing substituents promote the creation of an ammonium carboxylate salt, whereas the electron donors assist with the amic acid intermediate formation. These salts and amic acids were further converted into polyimides by thermal treatment. The structures of the intermediates and PAIs were characterized by Fourier transform infrared, 1H nuclear magnetic resonance (NMR), and 13C NMR spectroscopies, and their thermal properties were determined by differential scanning calorimetry and thermogravimetry. X-ray diffraction patterns and inherent viscosity values of these PAIs were also reported. By using these chemical transformations, waste poly(ethylene terephthalate) bottles were converted into high-performance PAIs. These PAIs can be used as membrane-modifying agents for industrial separation applications.

Recent advances in triphenylamine-based electrochromic derivatives and polymers

Triphenylamine-containing electrochromic materials with great potential applications in low energy-consumption displays, light-adapting mirrors in vehicles, and smart windows have experienced an exponential growth of research interests. In this review, the newly developed triphenylamine-based derivatives and polymers are reviewed and elaborated.

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.

Synthesis of high Tg and organosoluble poly(N-arylene benzimidazole ether imide) copolymers by C–N/C–O coupling reaction

A series of poly( N-arylene benzimidazole ether imide) copolymers PEIBIs were prepared from 1H,3′H-5,5′-bis-benzimidazole, bisphenol-A and 4,4′-bis(4-fluorophthalimido)diphenyl ether by nucleophilic displacement polymerization. The resulting copolymers PEIBI(10–90) demonstrated moderate to good solubility in polar aprotic solvents and high glass transition temperatures ( Tgs) of 228–336°C, good thermal stability with 10% weight loss temperatures in the range of 503–548°C. All copolymer films showed good mechanical properties with tensile strengths of 101–130 MPa, tensile moduli of 3.3–4.0 GPa, elongations at break of 5–7%, and also presented low water uptake (0.15–0.34%). The wide-angle X-ray diffraction results revealed the amorphous nature of copolymers. The copolymer PEIBI-80 showed good balance in solubility, thermal and mechanical properties.

Phosphine oxide based polyimides: structure–property relationships

The PI flame retardance has been influenced by the variation of flexible segments leading to a reduction of THR.

Aromatic and Heterocyclic Polymers—What Future?

This paper discusses the evolution observed in the field of high performance polymers and tries to forecast the future in different domains. The paper is divided into four sections: 1. From the 1960s to the 21st century. 2. What’s new in chemistry and why? 3. What could be the future for high performance polymers in structural applications, electrical industries, electronic and electro-optical industries, membrane technologies, fuel cell membranes and other fields such as conductive polymers. 4. Concluding remarks.

Thermo-Processable Polyimides with High Thermo-Oxidative Stability as Derived from Oxydiphthalic Anhydride and Bisphenol a Type Dianhydride

Two series of homopolyimides based on oxydiphthalic anhydride and bisphenol A bisether-4-diphthalic anhydride were synthesized with 12 kinds of aromatic diamines. Several thermo-processable homopolyimides were the focus of further investigation. The structure–property relationships of these homopolyimides were examined as functions of the glass transition temperature ( Tg), melting point ( Tm), thermal decomposition temperature ( Td), and melt-flowability. The effects of the chemical and higher-order structures on these properties were discussed in this work to obtain an indication for the molecular design of high-performance thermoprocessable polyimides. A series of thermoplastic copolyimides were prepared to achieve higher Tg and Td without sacrificing thermo-processability. The copolyimides investigated exhibited a comparable or lower melt viscosity, higher Tg and Td, and higher long-term thermo-oxidative stability than those of ULTEM type polyimides. One of them exhibited a low melt viscosity (4700 poise at 400 °C), a high Tg (224 °C), and excellent thermo-oxidative stability.

New Silicon-Containing Phenylquinoxaline-Imide Polymers

A series of new aromatic polyimides, with phenylquinoxaline rings and dimethylsilane units, has been synthesized by solution polycondensation reaction of aromatic diamines containing phenylquinoxaline groups with a dianhydride incorporating dimethylsilane linkage, namely bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride. All polymers were easily soluble in organic solvents, such as N-methylpyrrolidinone, dimethylacetamide, pyridine and chloroform, and showed high thermal stability with decomposition temperature being above 480° C and glass transition temperature in the range of 245-266 'C. Very thin coatings were deposited from polymer solutions onto silicon wafers and exhibited smooth, pinhole-free surface in atomic force microscopy investigations. These polymers showed blue fluorescence in solution and films, with a maximum in the range of 415-425 nm.

Water as Solvent in Polyimide Synthesis II: Processable Aromatic Polyimides

Some representative thermal, chemical and mechanical characteristics of ‘commercial type’ polyimides are presented in this second paper in a series on using water as solvent in polyimide synthesis. The commercial types of polyimide that have been produced in this study are closely related to Kapton, Upilex R®, Upilex S®, Avimid N® and PMR-15. The chemical characterization of these materials using both nuclear magnetic resonance and Fourier Transform infrared indicate very pure and fully imidized products. The thermal and mechanical data from techniques such as thermogravimetric analysis, differential scanning calorimetry and dynamic mechanical thermal analysis reveal properties that are at least, equivalent to their commercial counterparts. Some improvement in processability is noted in pure materials, mixtures and chemically modified analogues of these well known polyimides. In addition this highly efficient one-pot method potentially provides economic advantages through low solvent cost and environmental impact benefits.

Comparison of Properties of Silicon-containing Poly(amide-imide)s

New silicon-containing poly(amide-imide)s have been synthesized by direct polycondensation of various aromatic diamines with a dicarboxylic acid containing the dimethylsilylene group and preformed imide cycles. These polymers are easily soluble in polar amidic solvents such as N-methylpyrrolidinone (NMP) or dimethylformamide (DMF) and can be cast into thin flexible films or coatings from such solutions. They show high thermal stability, with initial decomposition temperature being above 400°C and glass transition temperature in the range of 220-270°C. Very thin polymer films deposited by spin-coating technique onto silicon wafers showed a smooth, pinhole-free surface in atomic force microscopy investigations.

Influence of the Conformational Parameters on Physical Properties of some Heterocyclic Polymers containing Dimethylsilane Units

The conformational rigidity parameters of some poly(phenylquinoxaline-imide)s and poly (phenylquinoxaline-imide-amide)s containing dimethylsilane units were calculated by a Monte Carlo method with allowance for hindered rotation. Several physical properties such as solubility, glass transition temperature, initial decomposition temperature and dielectric constant are discussed in relation to the structure of the polymers and the rigidity of their chains.

Synthesis and Properties of Copolyimides Derived from Isometric Biphenyltetracarboxylic Dianhydrides (a-BPDA and i-BPDA) and Oxydiphthalic Dianhydride (ODPA) with 4,4’-Oxydianiline (4,4’-ODA)

Two series of polyimides were prepared by thermal imidization of polyamide acid derived from 2,3,3’,4’-biphenyltetracarboxylic dianhydride (a-BPDA), 2,3,2’,3’-biphenyltetracarboxylic dianhydride (i-BPDA) or 3,3’,4,4’-oxydiphthalic dianhydride (ODPA) and 4,4’-oxydianiline (4,4’-ODA). The properties of copolyimides derived from a-BPDA and i-BPDA were compared with those of the copolyimides based on a-BPDA and ODPA. The glass transition temperature ( Tg) of the former copolyimides increased with an increase of the i-BPDA component, whereas Tg of the later copolyimides decreased with the increase of the ODPA component. The i-BPDA-based copolyimides had higher Tg and better solubility than the a-BPDA homopolyimide, while the ODPA based copolyimides had higher elongation at break. The tensile, dynamic mechanical properties and coefficient of thermal expansion of these copolyimides were characterized.

New Silicon-Containing Poly(Imide-Amide)s

New aromatic silicon-containing poly(imide-amide)s have been synthesized by solution polycondensation of various aromatic diamines having ether bridges between phenylene rings with a diacid chloride containing silicon. These polymers are easily soluble in polar amidic solvents such as N-methyl-pyrrolidinone or dimethylformamide and can be cast into thin flexible films or coatings from such solutions. They show high thermal stability, with an initial decomposition temperature above 410°C and a glass transition temperature in the range of 251-285°C. Very thin polymer films deposited by the spincoating technique onto silicon wafers showed a smooth, pinhole-free surface in atomic force microscopy investigations.

Novel aromatic polyimides derived from 2,8-di(3-aminophenyl)dibenzofuran. Synthesis, characterization and evaluation of properties

Three aromatic polyimides (PIs) were prepared from a new aromatic diamine monomer derived from the rigid ring dibenzofuran.

Synthesis and properties of polyimides having a hexaphenylbenzene unit

Aromatic polyimides (PIs) with a hexaphenylbenzene unit were synthesized from 1,4-bis[4-(4-aminophenoxy)phenyl]-2,3,5,6-tetraphenylbenzene (1) and various tetracarboxylic dianhydrides by a conventional two-step procedure that included ring-opening polymerization in N-methyl-2-pyrrolidone and subsequent thermal cyclic dehydration. The PIs were characterized by X-ray diffraction, differential scanning calorimetry, thermogravimetry, and dynamic mechanical analysis. The PIs had glass transition temperatures in the range of 289–352°C, and all the polymers were amorphous. The structure–property relationships of these PIs were examined and compared with those of the previously prepared analogous PIs from 4,4′-bis(4-aminophenoxy)biphenyl (2) and 4,4′-bis(4-amino-2-phenylphenoxy)biphenyl (3). Water absorption and dielectric constants of the PIs were also compared and discussed on the basis of imide content per repeating unit.