Synthesis and characterization of organosoluble and transparent polyimides derived from trans‐1,2‐bis(3,4‐dicarboxyphenoxy)cyclohexane dianhydride

A novel dianhydride, trans‐1,2‐bis(3,4‐dicarboxyphenoxy)cyclohexane dianhydride (1,2‐CHDPA), was prepared through aromatic nucleophilic substitution reaction of 4‐nitrophthalonitrile with trans‐cyclohexane‐1,2‐diol followed by hydrolysis and dehydration. A series of polyimides (PIs) were synthesized from one‐step polycondensation of 1,2‐CHDPA with several aromatic diamines, such as 2,2′‐bis(trifluoromethyl)biphenyl‐4,4′‐diamine (TFDB), bis(4‐amino‐2‐trifluoromethylphenyl)ether (TFODA), 4,4′‐diaminodiphenyl ether (ODA), 1,4‐bis(4‐aminophenoxy)benzene (TPEQ), 4,4′‐(1,3‐phenylenedioxy)dianiline (TPER), 2,2′‐bis[4‐(3‐aminodiphenoxy)phenyl]sulfone (m‐BAPS), and 2,2′‐bis[4‐(4‐amino‐2‐trifluoromethylphenoxy)phenyl]sulfone (6F‐BAPS). The glass transition temperatures (T_gs) of the polymers were higher than 198°C, and the 5% weight loss temperatures (T_d5%s) were in the range of 424–445°C in nitrogen and 415–430°C in air, respectively. All the PIs were endowed with high solubility in common organic solvents and could be cast into tough and flexible films, which exhibited good mechanical properties with tensile strengths of 76–105 MPa, elongations at break of 4.7–7.6%, and tensile moduli of 1.9–2.6 GPa. In particular, the PI films showed excellent optical transparency in the visible region with the cut‐off wavelengths of 369–375 nm owing to the introduction of trans‐1,2‐cyclohexane moiety into the main chain. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42317.     

Preparation and proton conductivity of phosphoric acid‐doped blend membranes composed of sulfonated block copolyimides and polybenzimidazole

A series of phosphoric acid (PA)‐doped blend membranes composed of block or random sulfonated polyimides (SPIs) and polybenzimidazole (PBI) were prepared with similar PA contents to investigate the influence of chemical structures of SPIs on proton conductivity. The proton conductivity of a PA‐doped blend membrane containing block‐type SPI, PA‐bSPI(80/20)/oPBI, was higher than that of the corresponding pristine block‐type SPI, PA‐SPI/PBI containing random‐type SPI and Nafion membranes over a wide temperature range, and reached 0.37 S cm^?1 at 90 °C and 98% relative humidity. The PA‐bSPI(80/20)/oPBI membrane also showed distinct proton conductivity even at low humidity due to a new proton transport pathway among PA and sulfonic acid groups. Also, the novel PA‐doped blend membrane showed higher proton conductivity than Nafion at both above 100 °C and below 0 °C under low relative humidity conditions. © 2013 Society of Chemical Industry     

Synthesis and properties of novel polyimides from 3‐(4‐aminophenylthio)‐N‐aminophthalimide

A novel, asymmetric diamine, 3‐(4‐aminophenylthio)‐N‐aminophthalimide, was prepared from 3‐chloro‐N‐aminophthalimide and 4‐aminobenzenethiol. The structure of the diamine was determined via IR and ¹H‐NMR spectroscopy and elemental analysis. A series of polyimides were synthesized from 3‐(4‐aminophenylthio)‐N‐aminophthalimide and aromatic dianhydrides by a conventional two‐step method in N,N‐dimethylacetamide and by a one‐step method in phenols. These polyimides showed good solubility in 1‐methyl‐2‐pyrrolidinone, m‐cresol, and p‐chlorophenol, except polyimide from pyromellitic dianhydride, which was only soluble in p‐chlorophenol. The 5% weight loss temperatures of these polyimides ranged from 460 to 498°C in air. Dynamic mechanical thermal analysis indicated that the glass‐transition temperatures of the polyimides were in the range 278–395°C. The tensile strengths at break, moduli, and elongations of these polyimides were 146–178 MPa, 1.95–2.58 GPa, and 9.1–13.3%, respectively. Compared with corresponding polyimides from 4,4′‐diamiodiphenyl ether, these polymers showed enhanced solubility and higher glass‐transition temperatures. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis,characterization, and gas transport properties of new semifluorinated poly(ether imide)s containing cardo moiety

A series of new semifluorinated poly(ether imide)s (PEI)s was synthesized from a diamine monomer, 9,9‐bis ‐[3‐phenyl‐4‐{2′‐trifluoromethyl‐4′‐(4′′‐aminophenyl)phenoxy} phenyl]fluorene on reaction with three different aromatic dianhydrides namely, 4,4′‐(4,4′‐isopropylidenediphenoxy)bis (phthalic anhydride), 4,4'‐(hexafluoro‐isopropylidene)diphthalic anhydride, and 4,4'‐oxydiphthalic anhydride. The PEIs were well characterized by elemental analysis, spectroscopic, thermal, mechanical, electrical, and optical techniques. The synthesized PEIs showed high glass transition temperature (T_g up to 288 °C) and high thermal stability (T_{d ,10} up to 521 °C under synthetic air), high tensile strength, up to 76 MPa and low dielectric constant (?) (2.35–2.61 at 1 MHz). The membranes prepared from these polymers were studied for their gas permeability for four different gases CO₂, O₂, N₂, and CH₄. The PEI membranes showed high gas permeability (P _CO2 up to 70.3 and P _O2 up to 16.7 Barrer) and high permselectivity (P _CO2/P _CH4 up to 73.6 and P _O2/P _N2 up to 13.4); for the O₂/N₂ gas pair the PEIs surpassed the present upper boundary limit of 2008 drawn by Robeson. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45213.     

Nanostructured membranes based on sulfonated poly(aryl ether sulfone) and silica for fuel‐cell applications

Nanostructured sulfonated poly(aryl ether sulfone) (SPSU) membranes were made from SPSU/silica composites through the addition of amorphous, precipitated, and micronized silica particles (Tixosil 333) and short or segmented linear structures. Linear and branched segments of silica were obtained from the in situ reaction of tetraethoxysilane (TEOS) in an SPSU solution through a sol–gel acid‐catalyzed process. Different amounts of silica in the SPSU composites were prepared to evaluate their influence on the ionic conductivity, the water and alcohol solution sorption capacities, and the stability in an ethanol medium. The effect of silica (Tixosil) on the conductivity was higher than that of the silica made from TEOS in SPSU composites. The conductivities of the membranes containing 10% Tixosil and 6.6% silica prepared from TEOS were measured at 80°C; their values were 60 and 33 mS/cm, respectively. Furthermore, a membrane made of a silica blend (5% Tixosil and 3% TEOS) in SPSU attained a value of 92 mS/cm, whereas the commercial membrane Nafion 117, used as a reference, had a conductivity of 54 mS/cm measured under the same conditions. All those composites membranes could be used as components in hydrogen fuel cell. However, only the SPSU/2% Tixosil composite could be used in both hydrogen and ethanol direct fuel cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of poly(4‐diphenylaminostyrene)‐Poly(9‐vinylanthracene) binary block copolymer

Block copolymerization of plural types of monomers offers a new opportunity for the preparation of a variety of multifunctional polymers. Poly(4‐diphenylaminostyrene) (PDAS)‐poly(9‐vinylanthracene) (PVAN) binary block copolymer (PDAS‐PVAN) was synthesized by (living) anionic polymerization using the benzyllithium/N,N,N′,N′‐tetramethylethylenediamine system. The photoluminescence emission of PDAS‐PVAN was enhanced by the fluorescence resonance energy transfer from PDAS block to PVAN block in PDAS‐PVAN. The hole drift mobility of the copolymer was controllable by the amount of triphenylamino groups in the polymer chain. The optical and electrical properties of PDAS‐PVAN were adjustable through the polymer chain structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of sulfonated poly(arylene‐co‐naphthalimide)s for use as proton exchange membranes

In this study, conductive porous composites were fabricated using the host substrate with an interconnected porous network, followed by the penetration and deposition of polypyrrole (PPy) to create a continuous conductive network. The open‐porous host substrate was processed using polylactide (PLA) with compression molding and salt leaching techniques. Three different salt contents were varied from 75 wt %, 85 wt %, and 90 wt %, which were referred to by their salt‐to‐polymer mass ratios of 3, 6, and 9, respectively. The porous network was made conductive by coating its interior surfaces through in situ polymerization of PPy using iron (III) chloride as the oxidant species. These porous composites were then characterized to analyze the relationships between their morphology and their physical, conductive, and mechanical properties. The mechanical properties were then fitted with numerically simulated results from finite element modeling (FEM). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Anionic block copolymerization of cyclotetrasiloxanes initiated by 4,4'‐bis(dimethyllithiioxylsilyl)diphenyl ether

The anionic copolymerization of cyclotetrasiloxanes initiated by 4,4′‐bis(dimethyllithiioxylsilyl)diphenyl ether (BDMOLiPE) was carried out for the preparation of poly(diphenyl‐dimethyl‐diphenyl)siloxane block copolymers (PMP). To reduce redistribution reaction, the lithium‐based dianionic initiator (BDMOLiPE) was first used for the copolymerization of the cyclotetrasiloxane monomers without solvent, with dimethyl formamide (DMF) as a promotor. The cyclotetrasiloxanes used involved octamethylcyclotetrasiloxane (D₄), octaphenylcyclotetrasiloxane (P₄), and tetramethyl‐tetravinylcyclotetrasiloxane (V₄). The copolymers obtained were characterized withproton nuclear magnetic resonance spectroscopy, infrared spectroscopy, intrinsic viscosity([η]) determination, transmission electron microscopy, and wide‐angle X‐ray diffraction analysis. The results illustrate that the products should belong to block copolymers but not be too perfect because the block copolymers were scrambled to a certain extent during the copolymerization process. However, we can approximately express them as PMP and PMVP, according to the different order of the feeding in raw materials. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1203–1210, 2001     

Synthesis and characterization of a new type of sulfonated poly(ether ether ketone ketone)s for proton exchange membranes

A novel series of sulfonated poly(ether ether ketone ketone)s (SPEEKKs) were prepared by aromatic nucleophilic polycondensation with different ratios of 1,3‐bis(3‐sodium sulfonate‐4‐fluorobenzoyl)benzene to 1,3‐bis(4‐fluorobenzoyl)benzene. ¹H‐NMR spectroscopy was used to confirm the degrees of sulfonation (DS) of the polymers. Thermal stabilities of the SPEEKKs in acid form were characterized by thermogravimetric analysis (TGA), which showed that SPEEKKs were excellently thermally stable at high temperatures. SPEEKK polymers can be easily cast into tough membranes. Both of proton conductivity and methanol diffusion coefficient have been tested in this article. Other properties of the SPEEKK membranes were investigated in detail. The results show that the SPEEKK membranes are promising in proton exchange membrane fuel cells (PEMFCs) application. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of chemical compositions on the properties of random and multiblock sulfonated poly(arylene ether sulfone)‐based proton‐exchange membranes

The influence of chemical compositions on the properties of sulfonated poly(arylene ether sulfone)‐based proton‐exchange membranes was studied. First, we synthesized three different series of random SPAES copolymers using three kinds of hydrophobic monomers, including 4,4′‐dihydroxyldiphenylether, 2,6‐dihydroxynaphthalene (DHN), and 4,4′‐hexafluoroisopropylidenediphenol (6F‐BPA) to investigate effects of hydrophobic components on the properties of SPAES membranes as proton‐exchange membranes. Random SPAES copolymers with 6F‐BPA showed the highest proton conductivity while random SPAES copolymers with DHN displayed the lowest methanol permeability among the three random copolymers. Subsequently, we synthesized multiblock SPAES using the DHN as a hydrophobic monomer and studied the effect of the length of hydrophilic segments in the multiblock SPAES copolymers on membrane performance. The results indicated that longer hydrophilic segments in the copolymers led to higher water uptake, proton conductivity, and proton/methanol selectivity of membranes even at low humidity. In addition, the morphology studies (AFM and SAXS measurements) of membranes suggested that multiblock copolymers with long hydrophilic segments resulted in developed phase separation in membranes, and ionic clusters formed more easily, thus improving the membrane performance. Therefore, both the kinds of hydrophobic monomers and the length of hydrophilic segments in SPAES copolymers would influence the membranes performance as proton‐exchange membranes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and properties of poly(ether imide)s derived from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and aromatic ether–diamines

A series of poly(ether imide)s (PEIs) with light colors and good mechanical properties were synthesized from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and various aromatic ether–diamines via a conventional two‐step polymerization technique that included ring‐opening polyaddition at room temperature to poly(amic acid)s (PAAs) followed by thermal imidization. The precursor PAAs had inherent viscosities ranging from 0.71 to 1.19 dL/g and were solution‐cast and thermally cyclodehydrated to flexible and tough PEI films. All of the PEI films were essentially colorless, with ultraviolet–visible absorption cutoff wavelengths between 377 and 385 nm and yellowness index values ranging from 10.5 to 19.9. These PEIs showed high thermal stabilities with glass‐transition temperatures of 206–262°C and decomposition temperatures (at 10% weight loss) higher than 478°C. They also showed low dielectric constants of 3.39–3.72 (at 1 MHz) and low water absorptions below 0.85 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of ABA type tri‐block copolymers derived from p‐dioxanone,L‐lactide and poly(ethylene glycol)

A series of triblock co‐polymers, consisting of a poly(ethylene glycol) (PEG) central block joined to two blocks of random p‐dioxanone‐co‐L ‐lactide copolymers were synthesized by ring‐opening polymerization of p‐dioxanone (PDO) and L ‐lactide (LLA) initiated by PEG in the presence of stannous 2‐ethylhexanoate catalyst. The resulting copolymers were characterized by various techniques including ¹H and ¹³C NMR and FTIR spectroscopies, gel permeation chromatography, inherent viscosity, wide‐angle X‐ray diffractometry (WAXD) and differential scanning calorimetry (DSC). The conversion of PDO and L ‐lactide into the polymer was studied various mole ratios and at different polymerization temperature from ¹H NMR spectra. Results of WAXD and DSC showed that the crystallinity of PEG macroinitiator was greatly influenced by the composition of PDO and L ‐lactide in the copolymer. The triblock copolymers with low molecular weight were soluble in water at below room temperature. © 2003 Society of Chemical Industry     

Synthesis and characterization of benzimidazole‐based low CTE block copolyimides

A series of block and random copolyimide films were synthesized from various molar ratios of two diamines, rigid 2‐(4‐aminophenyl)‐5‐aminobenzimidazole (APBI) and flexible 4,4′‐oxydianiline (ODA) by polycondensation with dianhydride 3,3′,4,4′‐biphenyltetracarboxylic dianhydride. The contents of APBI ranged from 10 to 60 mol % in copolyimides. The copolyimide films obtained by thermal imidization of poly(amic acid) solutions, were characterized by TMA, DMA, TGA, DSC, wide‐angle X‐ray diffraction, FTIR, tensile testing, water uptake (WU), and dielectric constant measurements. Rigid heterocyclic diamine APBI with interchain hydrogen bonding capability, led to low coefficient of thermal expansion (CTE), high T_g, high thermal stability and better mechanical properties. Increasing the APBI mol % caused a gradual decrease in the CTE and increase in T_g, thermal stability and tensile strength properties of the copolyimides films. Moreover, significantly enhanced thermal and mechanical properties of the block copolyimides were also found as compared to random copolyimides. The block copolyimide with APBI content of 60 mol %, achieved excellent properties, that is, a low CTE (4.7 ppm/K), a high T_g at 377°C, 5% weight loss at 562°C and a tensile strength at 198 MPa. This can be interpreted because of comparatively higher degree of molecular orientation in block copolyimides. These copolyimides also exhibited better dielectric constant and WU. This combination of properties makes them attractive candidates for base film materials in future microelectronics. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Molecular simulation of the glass transition and proton conductivity of 2,2′‐benzidinedisulfonic acid and 4,4′‐diaminodiphenylether‐2,2′‐disulfonic acid‐based copolyimides as polyelectrolytes for fuel cell applications

The glass transition temperatures (T_gs) and proton conductivities of polyimides synthesized from naphthalene‐1,4,5,8‐tetracarboxylic dianhydride (NTDA), 2,2′‐benzidinedisulfonic acid (BDSA), 4,4′‐diaminodiphenylether‐2,2′‐disulfonic acid (ODADS), and non‐sulfonated diamine monomers have been predicted using molecular dynamics simulations. The specific volumes for two dry and four hydrated NTDA‐based polyimides were plotted versus temperatures above and below T_gs to obtain the glass transition temperatures. The simulation results suggest that the ODADS‐based polyimide membranes exhibit lower T_gs and thus better mechanical properties than the BDSA‐based polyimides, which may be attributed to the high mobility of backbones of ODADS as supported by the vectorial autocorrelation function (VACF) results of this study. In addition, comparison of the simulated T_gs for the dry and hydrated ODADS‐based polyimides has shown that water content in polyimides can affect their T_gs. The proton conductivities of a representative polyimide in both dry and hydrated conditions have been obtained from molecular dynamics simulations of the proton and hydronium ion diffusion. The simulated conductivity for the hydrated NTDA‐ODADS/BAPB cell is in reasonable agreement with the experimental value obtained from the AC impedance method. The relationship between the chemical composition, chain flexibility, and the glass transition and proton conduction of these NTDA‐based polyimides was explored on the basis of VACF and pair correlation function analysis. Copyright © 2006 Society of Chemical Industry     

Comb-shaped block poly(arylene ether sulfone ketone)s for anion exchange membranes

A well-designed architecture is presented here to construct high-performance anion exchange membranes (AEMs). A series of quaternized fluorene-containing block poly(arylene ether sulfone ketone)s (QFPESK-m-n) is synthesized as the main chains, and grafted with comb-shaped C8 long alkyl chains for the AEMs. By varying the hydrophilic segment’ length, there has been a significant change in the microstructure as well as phase separation morphology of the membranes, as confirmed by atomic force microscopy. Hence the as-prepared AEMs with moderate ion exchange capacities (IECs) show enhanced hydroxide conductivities in the range of 28.8―94.7 mS⋅cm⁻¹ from 30 to 80°C. Furthermore, based on the block backbones and hydrophobic comb-shaped alkyl chains, the AEMs show low-level swelling ratios of 4.3% to 9.2% at 30°C and from 6.2% to 13.2% at 80°C, and superior ratios of conductivity to swelling. In addition, the QFPESK-m-n AEMs also depict acceptable mechanical properties, good thermal stability and an optimizable alkaline stability.     

Synthesis and characterization of block comb‐like copolymers P(A‐MPEO)‐block‐PSt

Amphiphilic block comb‐shaped copolymers, poly[poly(ethylene oxide) methyl ether acrylate]‐block‐polystyrene [P(A‐MPEO)‐block‐PSt] with PSt as a handle, were successfully synthesized via a macromonomer technique. The reaction of MPEO with acryloyl chloride yielded a macromonomer, A‐MPEO. The macroinitiator PSt capped with the dithiobenzoate group (PSt‐SC(S)Ph) was prepared by reversible addition–fragmentation transfer (RAFT) polymerization of styrene in the presence of benzyl dithiobenzoate, and used as macroinitiator in the controlled radical block copolymerization of A‐MPEO at room temperature under ⁶⁰Co irradiation. After the unreacted macromonomer A‐MPEO had been removed by washing with hot saturated saline water, block comb‐shaped copolymers were obtained. Their structure was characterized by ¹H NMR spectroscopy and gel permeation chromatography. The phase transition and self‐assembling behaviour were investigated by atomic force microscope and differential scanning calorimetry. Copyright © 2004 Society of Chemical Industry     

Imidazolium ionic liquid incorporation on sulfonated poly(styrene‐isobutylene‐styrene) proton exchange membranes

Ionic liquids (ILs) with different anions and cations were incorporated in sulfonated poly(styrene‐isobutylene‐styrene) (SIBS) to modify its chemical, morphological, and transport properties for direct methanol fuel cell (DMFC) applications. Different loadings of IL and different solvents were studied to have a better understanding of the incorporation process and the ability of the solvent to affect the interaction of the IL with the sulfonated polymer. Morphological characterization with SAXS and AFM suggested changes caused by the incorporation of the IL and by the solvent used. FT‐IR spectra showed small variations in energy related to interactions of the IL with the sulfonic groups which caused thermogravimetric stabilization of the ionic domains. Other results suggest that water has a very significant effect on the morphology, interaction with the IL, and transport properties of the membranes. Optimal concentration of IL (～10 mol %) provides enough water to produce efficient proton conductivity (0.15 S/cm) and minimal methanol permeability (0.8 × 10^?6 cm²/s). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44900.     

Polyphosphazene membranes. III. Solid‐state characterization and properties of sulfonated poly[bis(3‐methylphenoxy)phosphazene]

Poly[bis(3‐methylphenoxy)phosphazene] was sulfonated in a solution with SO₃ and solution‐cast into 100–200‐μm‐thick membranes from N,N‐dimethylacetamide. The degree of polymer sulfonation was easily controlled and water‐insoluble membranes were fabricated with an ion‐exchange capacity (IEC) as high as 2.1 mmol/g. For water‐insoluble polymers, there was no evidence of polyphosphazene degradation during sulfonation. The glass transition temperature varied from −28°C for the base polymer to −10°C for a sulfonated polymer with an IEC of 2.1 mmol/g. The equilibrium water swelling of membranes at 25°C increased from near zero for a 0.04‐mmol/g IEC membrane to 900 % when the IEC was 2.1 mmol/g. When the IEC was < 1.0 mmol/g, SO₃ attacked the methylphenoxy side chains at the para position, whereas sulfonation occurred at all available aromatic carbons for higher ion‐exchange capacities. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized microscopy showed that the base polymer, poly[bis(3‐methylphenoxy)phosphazene], was semicrystalline. For sulfonated polymers with a measurable IEC, the 3‐dimensional crystal structure vanished but a 2‐dimensional ordered phase was retained. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 387–399, 1999     

Synthesis and characterization of organo‐soluble polyimides derived from a new spirobifluorene diamine

Polyimides exhibit outstanding thermal and thermo‐oxidative stability, excellent solvent resistance, good mechanical and electrical properties and superior chemical resistance. However, their practical applications are frequently limited by their infusible and insoluble nature. Structural modifications of the polymer backbone have been utilized to modify polyimide properties, either by reducing the interaction or by reducing the stiffness of the polymer backbone. Novel organo‐soluble polyimides containing spirobifluorene units were synthesized by the polycondensation of 2,7‐bis‐amino‐2′,7′‐di‐t‐butyl‐9,9′‐spirobifluorene with three aromatic dianhydrides. The one‐step polymerization procedure was conducted at 200 °C in m‐cresol, and the structures of the resulting polyimides were confirmed using infrared and NMR spectroscopy. The weight‐average molecular weights and polydispersities of the resulting polymers were in the ranges 20 600–341 000 and 1.02–1.30, respectively. The glass transition temperatures of the polyimides were in the range 289–322 °C, and the 10% weight loss in nitrogen appeared at a temperature higher than 435 °C and the residual weight at 800 °C was above 58%. The spiro segment has been introduced into polyimides, resulting in amorphous polyimides, conferring on them an enhanced solubility and leading to a significant increase in both glass transition temperature and thermal stability. These types of materials have potential for many applications. Copyright © 2010 Society of Chemical Industry     

Synthesis and properties of polyimides from isomeric bis(dicarboxylphenylthio)diphenyl sulfone dianhydrides

4,4′-Bis(3,4-dicarboxyphenylthio)diphenyl sulfone dianhydride(4,4′-PTPSDA) and 4,4′-bis(2,3-dicarboxyphenylthio)diphenyl sulfone dianhydride(3,3′-PTPSDA) were synthesized from chlorophthalic anhydrides and bis(4-mercaptophenyl)sulfone. Their structures were determined via IR spectra, ¹H NMR and elemental analysis. A series of polyimides were prepared from isomeric PTPSDAs and aromatic diamines in 1-methyl-2-pyrrolidinone (NMP) via the conventional two-step method. Polyimides based on 4,4′-PTPSDA and 3,3′-PTPSDA have good solubility in polar aprotic solvents and phenols. The 5% weight-loss temperatures of isomeric polyimides were near 500 °C in N₂. DMTA and DSC analyses indicated that the glass-transition temperatures of polyimides from 3,3′-PTPSDA are higher than those of polyimides from 4,4′-PTPSDA. The wide-angle X-ray diffraction showed that all polyimides are amorphous. The polyimides from 3,3′-PTPSDA showed higher permeability but lower permselectivity compared with those from 4,4′-PTPSDA.