Structure‐property relationships for a series of amorphous partially aliphatic polyimides

High molecular weight, soluble, amorphous, partially aliphatic polyimides were successfully synthesized using an ester acid high‐temperature solution imidization route, which allows one to control desired glass‐transition (T_g) and processing temperatures. This method involves the prereaction of aromatic dianhydrides with ethanol and a tertiary amine catalyst to form ester acids, followed by the addition of diamines. Subsequent thermal reaction forms fully cyclized polyimides. This reaction pathway eliminates the need for anhydrous solvents and overcomes the problem of salt formation commonly observed for nucleophilic, more‐basic aliphatic amines when utilizing the traditional polyamic acid synthesis route. The molar ratio of aromatic‐to‐aliphatic diamines was varied to generate a series of copolyimides with the chosen dianhydride and tailor the physical properties for specific adhesive applications. This series of copolyimides was characterized by their molecular weight, T_g, thermal stability, coefficient of thermal expansion, refractive index, and dielectric constant. Structure‐property relationships were established. The γ and β sub‐T_g viscoelastic properties were researched to understand their molecular origins. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1503–1512, 2002     

Polyimides with alicyclic diamines. II. Hydrogen abstraction and photocrosslinking reactions of benzophenone-type polyimides

Photosensitive polyimides with alicyclic diamines and benzophenone moiety were prepared by reactions of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) with diamines in aprotic solvents, followed by thermal or chemical imidizations. Among them the polyimide from BTDA and bis(4-amino-3-methylcyclohexyl) methane (DMDHM) can be dissolved in several organic solvents such as dichloromethane, tetrachloroethane, and N-methyl-2-pyrrolidone (NMP). In order to compare properties of the polyimides with alicyclic diamines with those of corresponding aromatic polyimides, the UV absorption spectra and fluorescence spectra of these polyimides and their model compounds were investigated. No occurrence of charge transfer at photoexcited states was ascertained for the polyimides with alicyclic diamines. The hydrogen abstraction and crosslinking during photoirradiation have been studied to learn the influence of the elimination of charge transfer process in these photosensitive polyimides. The quantum yield of hydrogen abstraction for the model compound of alicyclic polyimides is 0.56 in THF measured with HPLC. The quantum yield for the photocrosslinking reaction of the solvent-soluble polyimide with alicyclic diamine, PI(BTDA/DMDHM), was determined to be 0.004 in air from gel permeation chromatography (GPC) measurement, which is four times higher than that for photosensitive polyimides with aromatic diamines. © 1994 John Wiley & Sons, Inc.     

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

Polyimides 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     

Polyimides with alicyclic diamines. I. Syntheses and thermal properties

The polyaddition reactions of alicyclic diamines such as 1,4-diaminocyclohexane (1,4-CHDA) or 4,4′-diaminodicyclohexylmethane (DCHM) and configurational isomers of 1,4-CHDA or DCHM with tetracarboxylic aromatic anhydrides in aprotic solvents were carried out to prepare high molecular weight poly(amic acid)s. Through the thermal imidization of poly(amic acid)s, several flexible polyimide films were prepared. Because of the stiffness of the alicyclic moieties in diamines, the resulting polyimides exhibit high glass transition temperatures (220–340°C) almost similar to those for corresponding aromatic polyimides which have phenylene groups in place of cyclohexyl groups, and show good thermal stability. The partial crystallization was observed for polyimides with trans-cyclohexyl moiety during the heating in differential scanning calorimetry and ascertained by wide-angle x-ray diffraction. Thus, the inhibition of the occurrence of charge transfer in polyimides is accomplished by introducing alicyclic diamines in place of aromatic diamines without reducing their thermal stability. © 1993 John Wiley & Sons, Inc.     

High-pressure synthesis and properties of aliphatic–aromatic polyimides via nylon-salt-type monomers derived from aliphatic diamines and benzophenonetetracarboxylic acid

Aliphatic polyimides (P-XBTA) having inherent viscosities of 0.4–1.4 dL/g were readily synthesized by the high-pressure polycondensation of the salt monomers, composed of aliphatic diamines having various methylene chain lengths (X = 4–12) and 3,3′,4,4′-benzophenonetetracarboxylic acid (BTA), under 200–250 MPa at 200–320°C. The salt monomers with odd-numbered methylene units were found to be more susceptible to crosslinking than those containing even-numbered methylene chains. The polyimides having even-numbered methylene units were highly crystalline, whereas those with odd-numbered methylene chains were crosslinked and therefore amorphous with only one exception, i.e., P-11BTA. The thermal behavior of these polymers was also studied. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 39–47, 1998     

Synthesis and characterization of soluble polyimides from 2,2-bis(4-aminophenyl)cycloalkane derivatives

New aromatic diamines [(1) and (2)] containing polycycloalkane structures between two benzene rings were synthesized by HCl-catalyzed condensation reaction of aniline hydrochloride and corresponding polycycloalkanone derivatives. The structures of diamines were identified by ¹H-NMR, ¹³C-NMR, FTIR spectroscopy, and elemental analysis. The polyimides were synthesized from the obtained diamines with various aromatic dianhydrides by one-step polymerization in m-cresol. The inherent viscosities of the resulting polyimides were in the range of 0.34–1.02 dL/g. The polyimides showed good thermal stabilities and solubility. All the polymers were readily soluble in N-methyl-2-pyrrolidone, m-cresol, tetrachloroethane, etc. Some of them were soluble even in chloroform at room temperature. The glass transition temperatures were observed in the range of 323–363°C, and all of the polymers were stable up to 400°C under nitrogen atmosphere. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3449–3454, 1999     

Synthesis and characterization of novel fully aliphatic polyimidosiloxanes based on alicyclic or adamantyl diamines

A series of fully aliphatic polyimidosiloxanes (APISiO) were prepared by poly(addition/condensation) reaction of bicyclo [2,2,2] oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride or cyclobutane‐1,2,3,4‐tetracarboxylic dianhydride and varying compositions of 1,3‐bis (3‐amino propyl)‐tetra methyl disiloxane and rigid adamantyl diamines (1,3‐diaminoadamantane or 3,3′‐diamino‐1,1′‐diadamantane) or flexible alicyclic diamines (4,4′‐methylene bis(cyclohexylamine) or 4,4′‐methylene bis(2‐methylcyclohexylamine)). High temperature one‐step synthesis in m‐cresol was employed to obtain APISiOs with intrinsic viscosity in the range of 0.28–0.59 dL/g. The final materials were characterized by ¹H and ¹³C NMR, ²⁹Si‐MAS‐NMR and IR spectroscopic analysis, thermogravimetric and differential scanning calorimetric analysis, and wide angle X‐ray diffractometry. UV–visible spectra revealed the optical behavior of the polyimides. It was found that the APISiOs containing appropriate ratio of adamantyl moieties together with flexible aliphatic siloxane groups exhibit good thermal and mechanical stabilities, solubility, fair transparency, and low dielectric constant (2.4–2.7). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5254–5270, 2006     

Synthesis and properties of polyimides from 4,4′-binaphthyl-1,1′,8,8′-tetracarboxylic dianhydride

4,4′-Binaphthyl-1,1′,8,8′-tetracarboxylic dianhydride was synthesized from 4-chloro-1,8-naphthalic anhydride and polymerized with aromatic and pliphatic diamines in m-cresol or N-methyl-2-pyrrolidinone (NMP). The polyimides, except for two derived from p-phenylenediamine and hydrazine, are soluble in 1,1,2,2-tetrachloroethane and NMP. Their intrinsic viscosities ranged from 0.36 to 2.20 dL/g. The polymers showed excellent thermal and thermooxidative stabilities and displayed weak glass transition temperatures. Young's moduli of some polymer films were in the range of 2.5 and 5.4 GPa at 30°C. The aliphatic polyimides exhibited a stronger fluorescence than the aromatic polyimides. © 1995 John Wiley & Sons, Inc.     

Preparation and properties of novel polyimides derived from 4‐aryl‐2,6 bis(4‐amino phenyl)pyridine

To prepare novel polyimides with enhanced thermal stability and high solubility in common organic solvents, diamine monomers, 4‐aryl‐2,6 bis‐(4‐amino phenyl)pyridine, were introduced. The diamines were reacted with three different conventional aromatic dianhydrides including pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and hexafluoroisopropylidene‐2,2‐bis(phthalic‐dianhydride) (6FDA) in dimethylacetamide solvent to obtain the corresponding polyimides via the polyamic acid precursors and chemical imidization. The monomers and polymers were characterized by Fourier transform infrared spectroscopy, ¹H NMR, mass spectroscopy, and elemental analysis; and the best condition of polymerization and imidization were obtained via the study of model compound. The polyimides showed little or no weight loss by thermogravimetric analysis up to 500 °C, and those derived from 6FDA exhibited good solubility in various polar solvents. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3826–3831, 2001     

New thermally stable and organosoluble heterocyclic poly(naphthaleneimide)s

As majority of polyheteroarylenes based on bis(naphthalic anhydrides), are difficult to process due to their infusiblity and insolubility in common organic solvents and solubility only in strong acids, this study is concerned with the synthesis and properties of new, easily processable polyimides and copolyimides containing naphthalene and oxadiazole rings. These polymers have been synthesized and their properties have been compared with regard to the influence of oxadiazole and naphthalene units on their physical properties. The polyimides were prepared by polycondensation reaction in solution of the aromatic diamines containing preformed oxadiazole ring with two dianhydrides having naphthalene units, at high temperature. Also, copolyimides were prepared by using a mixture of each naphthalene‐containing dianhydride, with hexafluoroisopropylidene‐dianhydride in the polycondensation reaction with the same diamino‐oxadiazoles. Most of the resulting polyimides and copolyimides were soluble in polar amidic solvents and in less polar solvents, and their solutions gave flexible films when spread onto glass plates. The thermal stability and glass transition temperature of these polyimides and copolyimides were measured and compared. The quality and the roughness of the spin‐coated films of these polymers were investigated by atomic force microscopy. The photoluminescence properties of the polymers in solution were studied to determine the color of emission. The UV absorption was also studied to determine the Stokes shift, and hence the possible reabsorption effects. The properties of the present polyimides make them attractive for applications in advanced optoelectronics and other related fields. Copyright © 2009 John Wiley & Sons, Ltd.     

Copoly(peryleneimide)s containing 1,3,4‐oxadiazole rings: Synthesis and properties

New copolyimides containing perylenediimide, oxadiazole and hexafluoroisopropylidene moieties were prepared by one‐step polycondensation reaction in solution at high temperature of aromatic diamines containing preformed oxadiazole ring with a mixture of a dianhydride having a perylene ring and another dianhydride with hexafluoroisopropylidene unit. The thermal stability and glass transition temperatures of these copolyimides were measured and compared with those of related polyimides. The solid polymers were also studied by polarized light microscopy and X‐ray diffraction which revealed a semicrystalline state consisting of face‐to‐face arranged columns of perylenediimide units. The film‐forming ability and properties of the resulting thin films were investigated by using atom force microscopy and scanning electron microscopy which showed that the films were organized into self‐assembled rod‐like structures. The UV‐Vis and photoluminescence properties in solution and in solid state were also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4230–4242, 2010     

Phosphinated phenols from acid‐fragmentation of bisphenols and their unsymmetrical diamine derivatives for copolyimides

Four novel diamines (9–12) were prepared by a two‐step procedure from phosphinated phenols (1–4) that were prepared from acid‐fragmentation of four bisphenols, including bisphenol A, 4,4′‐isopropylidenebis(2,6‐dimethylphenol), cis(4‐hydroxyphenyl)cyclohexane, and 9,9′‐bis(4‐hydroxyphenyl)fluorene, followed by nucleophilic addition of 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO). Copolyimides based on (9–12) /4,4′‐diaminodiphenyl ether (ODA)/dianhydride were prepared. The structure‐property relationship on the copolyimides was discussed. Due to the structural similarity, (9) /ODA‐based copolyimides were compared with (10) /ODA‐based copolyimides, while (11) /ODA‐based copolyimides were compared with (12) /ODA‐based copolyimides. The dimethyl substitutents cause (10) /ODA‐based copolyimides to display higher T_g, modulus, dimensional stability, contact angle, and better solubility than (9) /ODA‐based copolyimides. (12) /ODA‐based copolyimides that exhibit fluorene moieties display higher T_g and thermal stability, but a lower contact angle and poorer solubility than (11) /ODA‐based copolyimides that exhibit cyclohexane moieties. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 390–400     

Synthesis and characterization of some novel aromatic polyimides

Three new diamines 1,2-di(p-aminophenyloxy)ethylene, 2-(4-aminophenoxy)methyl-5-aminobenzimidazole and 4,4-(aminopheyloxy) phenyl-4-aminobenzamide were synthesized and polymerized with 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BP), 4,4′-(hexafluoroisopropyledene)diphthalic anhydride (HF) and 3,4,9,10-perylene tetracarboxylic acid dianhydride (PD) either by one step solution polymerization reaction or by two step procedure. The later includes ring opening poly-addition to give poly(amic acid), followed by cyclodehydration to polyimides with the inherent viscosities 0.62-0.97 dl/g. Majority of polymers are found to be soluble in most of the organic solvents such as DMSO, DMF, DMAc, m-cresol even at room temperature and few becomes soluble on heating. The degradation temperature of the resultant polymers falls in the ranges from 240 °C to 550 °C in nitrogen (with only 10% weight loss). Specific heat capacity at 300 °C ranges from 1.1899 to 5.2541 J g⁻¹ k⁻¹. The maximum degradation temperature ranges from 250 to 620 °C. T_g values of the polyimides ranged from 168 to 254 °C.     

Novel polyimides with p-nitrophenyl pendant groups. Synthesis and characterization

Polyimides derived from a new dianhydride with p-nitrophenyl pendant groups have been synthesized and their properties compared with those of a reference series, without side groups. The polymers were obtained by combination of the novel monomer with aromatic diamines, in a two-step procedure that involved the synthesis of poly(amic acid) or poly(amic silyl ester) intermediates and the cyclization of them to polyimides by thermal treatment. The introduction of the polar nitro groups caused significant increase of the T_gs. On the contrary, the thermal stability was reduced because of the breakdown of C_Ar—NO₂ linkages around 400^oC. A slight decrease in mechanical properties was observed, due to the bulkiness of the side groups, that also produced an important decrease in the strength of the β relaxation, as determined by dynamic mechanical analysis. The solubility of the current polyimides in organic solvents was as poor as that of the parent unsubstituted polymers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3377–3384, 1999     

Synthesis and characterization of novel polyimides with bulky pendant groups

New dianhydrides containing t‐butyl and phenyl pendant groups have been synthesized and used as monomers, together with commercial diamines, to prepare novel polyimides. The influence of the chemical structure of the monomers on their reactivity has been studied by quantum semiempirical methods. The polyimides have been characterized by FTIR and by NMR in the case of soluble polymers. The presence of pendant groups and the method used to imidize polyimide precursors greatly affected polymer properties such as solubility, glass transition temperature, thermal stability, and mechanical properties. As a rule, the novel polyimides showed better solubility in organic solvents than the parent polyimides. Glass transition temperatures in the range 250–270°C and decomposition temperatures over 520°C were observed for the set of current polymers. Tensile strengths up to 135 MPa and mechanical moduli up to 3.0 GPa were measured on films of the current polyimides. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 805–814, 1999     

Synthesis and electrooptical properties of triphenylamine- and oxadiazole-containing polymers

Soluble aromatic polyimides and copolyimides are synthesized on the basis of 4,4′-diaminotriphenylamine and oxadiazole-containing diamines. Poly(ester oxadiazoles) are prepared from acid dichlorides or oxadiazole-containing acid dihydrazides. The optical, electrochemical, and thermal properties of the polymers are investigated. It is shown that oxadiazole-containing polyimides and poly(ester oxadiazoles) are able to transfer electrons, while triphenylamine-containing polyimides and copolyimides can transfer holes and electrons.     

Structure-property study of polyimides derived from PMDA and BPDA dianhydrides with structurally different diamines

A series of aromatic diamines were polymerized with two aromatic dianhydrides, pyromellitic dianhydride and 3,3^′,4,4^′-biphenyltetracarboxylic dianhydride, and the resulting poly(amic acid)s were thermally cyclodehydrated to aromatic polyimides. The polyimides were characterized by determining the glass transition temperatures (T_g), thermal stability, coefficients of thermal expansion, and wide-angle X-ray diffraction. Structure-property relationships are elucidated and discussed in terms of the structural fragments in the polymer chain. The PMDA-based polyimides generally revealed a higher T_g than the corresponding BPDA-based analogues. Generally, the dilution of the imide content by the insertion of oxyphenylene segments into the diamines significantly reduced the T_g. The introduction of m- or o-phenylene units into the polymer backbone usually resulted in a decrease in T_g. The attachment of pendant groups on the backbone may lead to decreased or increased T_gs, depending on the structure of pendant groups. As evidenced by X-ray diffraction, the polyimides derived from rigid, rod-like diamines or the diamines having two or three p-oxyphenylene showed a higher crystalline tendency. The presence of aliphatic pendant groups slightly reduced the thermal stability of the polyimides. The other structural changes did not show a dramatic influence on the thermal stability. Some polyimides obtained from p- or m-phenylenediamine had low thermal expansion coefficients below 2×10−5°C⁻¹.     

Aromatic Copolyimides Containing Perylene Units

Perylene-containing copolyimides have been synthesized by one-step polycondensation reaction under high temperature of two different aromatic diamines with a mixture of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and 4,4'-hexafluoroisopropylidene diphthalic anhydride (6FDA). The copolyimides were soluble in polar amidic solvents and their solutions gave flexible thin films when spread onto glass plates. Very thin films obtained by spin coating had smooth surfaces and were self-organized into vertically segregated structures. The polymers were highly thermostable, their decompositions being above 470 °C and displayed reasonable high glass transition temperature values. After being excited with UV light, the polymers emitted light in the bluish and green-yellow domains.     

Synthesis and properties of novel sulfonated (co)polyimides bearing sulfonated aromatic pendant groups for PEFC applications

Novel sulfonated diamines bearing aromatic pendant groups, namely, 3,5‐diamino‐3′‐sulfo‐4′‐(4‐sulfophenoxy) benzophenone (DASSPB) and 3,5‐diamino‐3′‐sulfo‐4′‐(2,4‐disulfophenoxy) benzophenone (DASDSPB), were successfully synthesized. Novel side‐chain‐type sulfonated (co)polyimides (SPIs) were synthesized from these two diamines, 1,4,5,8‐naphthalene tetracarboxylic dianhydride (NTDA) and nonsulfonated diamines such as 4,4′‐bis(3‐aminophenoxy) phenyl sulfone (BAPPS). Tough and transparent membranes of SPIs with ion exchange capacity of 1.5–2.9 meq g^?1 were prepared. They showed good solubility and high thermal stability up to 300 °C. They showed isotropic membrane swelling in water, which was different from the main‐chain‐type and sulfoalkoxy‐based side‐chain‐type SPIs. The relative humidity (RH) and temperature dependence of proton conductivity were examined. At low RH, the novel SPI membranes showed much higher conductivity than the sulfoalkoxy‐based SPIs. They showed comparable or even higher proton conductivity than Nafion 112 in water at 60 °C (>0.10 S cm^?1). The membrane of NTDA‐DASDSPB/BAPPS (1/1)‐s displayed reasonably high proton conductivities of 0.05 and 0.30 S cm^?1 at 50 and 100% RH, respectively, at 120 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2862–2872, 2006     

Synthesis of copolyimides based on room temperature ionic liquid diamines

Block copolyimides based on aromatic dianhydrides and diamines copolymerized with diamino room temperature ionic liquid (RTIL) monomers were synthesized over a range of compositions. Specifically, two diamino RTILs, 1,3‐di(3‐aminopropyl) imidazolium bis[(trifluoromethyl)sulfonyl] imide ([DAPIM] [NTf₂]) and 1,12‐di[3‐(3‐aminopropyl) imidazolium] dodecane bis[(trifluoromethyl) sulfonyl] imide ([C₁₂ (DAPIM)₂] [NTf₂]₂) were synthesized using a Boc protection method. The two RTILs were reacted with 2,2‐bis(3,4‐carboxylphenyl) hexafluoropropane dianhydride (6FDA) to produce 6FDA‐RTILs oligomers that formed the RTIL component for the block copolyimides. The oligomers were reacted with 6FDA and m‐phenylenediamine (MDA) at oligomer concentration from 6.5 to 25.8 mol % to form block copolyimides. Increasing the concentration of the 6FDA‐RTIL oligomer in the block copolyimides resulted in a decrease in the thermal degradation temperature, glass transition temperature and an increase in the density. The gas permeability of the RTIL based block copolyimide decreased but the ideal permeability selectivity for CO₂/CH₄ gas pair increased relative to the pure 6FDA‐MDA. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4036–4046, 2010