Homopolyimides containing both benzimidazole and benzoxazole with high Tg and low coefficient of thermal expansion

A pair of isomer diamines containing both benzimidazole and benzoxazole and derived homopolyimides were synthesized for the first time. Due to rich rigid and linear benzoazole units, as well as the strong intermolecular interactions from the hydrogen bonding and the charge transfer complexation (CTC), the obtained polyimides (PIs) exhibited outstanding thermal properties, including high thermal weight loss temperature (T_d5% = 540–561°C), high glass transition temperature (T_g = 392–421°C), and low coefficient of thermal expansion (CTE = 1.3–20.9 ppm/°C). In addition, the obtained PIs also showed ideal mechanical properties (T_S = 189–240 MPa, T_M = 4.1–5.0 GPa and E_B = 2.9%–4.7%). These potential novel PI films with high T_g and low CTE were expected to be applied to next generation of flexible display substrate material.     

Synthesis of polyimides with lower H2O-absorption and higher thermal properties by incorporation of intramolecular H-bonding

To introduce intramolecular hydrogen bonds in the polyimides (PIs), 5(6)-amino-2-(5-aminopyridin-2-yl)-benzimidazole (PyPABZ) were designed and synthesized. The intramolecular interaction was indicated by Fourier transform infrared when different copolyimides were prepared with 4,4′-oxydianiline and PyPABZ. These modified poly(benzimidazole imide)s eliminate the problem of high water absorption for benzimidazole (BI)-containing PIs in the materials applications. Moreover, the high packing coefficient and rigidity of these copolyimides caused by the strong intramolecular interaction from the H-bonding and the resulting PIs exhibited outstanding thermal properties such as high glass-transition temperature (T_g) and low coefficient of thermal expansion.     

Heat-resistant polyimides with low CTE and water absorption through hydrogen bonding interactions

A novel diamine, 1H,1′H-(2,2′-bibenzimidazole)-5,5′-diamine (DPABZ), containing bisbenzimidazole unit was successfully synthesized, and used to prepare a series of copolyimides BPDA:(ODAm/DPABZn) by polycondensation with 4,4-diaminodiphenyl ether (ODA) and 4,4-biphthalic anhydride (BPDA). For comparison, a series of copolyimides BPDA:(ODAm/PABZn) based on another benzimidazole diamine 5-amino-2-(4-aminobenzene)-benzimidazole (PABZ) was also prepared. As a result, with the increase of PABZ or DPABZ content, the heat resistance (T_g and T_d) and mechanical properties (σ and E) of the resulting polyimide (PI) films increased, while the coefficient of thermal expansion (CTE) decreased. Overall, the DPABZ-based PIs showed higher T_g values and much lower CTE values than PABZ. As the content of PABZ increased, the water absorption of PABZ-based PIs increased obviously, but no significant change in DPABZ-based PIs. The intramolecular hydrogen bonding in DPABZ-based PIs caused by the diamine DPABZ was believed to be the reason for the aforementioned differences. The BPDA: DPABZ film with low-water adsorption of 2.1%, high-T_g value of 436°C and low-CTE value of 5.4 ppm/°C could be a promising new generation of flexible display substrates.     

Facile and efficient preparation of phosphinate‐functionalized aromatic diamines and their high‐Tg polyimides

Two novel phosphorus‐functionalized aromatic diamines, 1,1‐bis(4‐aminophenyl)‐1‐(6‐oxido‐6H‐dibenz <c,e> <1,2> oxaphosphorin‐6‐yl)ethane ( 1 ) and bis(4‐aminophenyl)‐(6‐oxido‐6H‐dibenz <c,e> <1,2> oxaphosphorin‐6‐yl)phenylmethane ( 2 ), were prepared from 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide, 4‐aminoacetophenone, or 4‐aminobenzophenone in excess aniline using p‐toluenesulfonic acid monohydrate as catalyst by an efficient, one‐pot procedure. The effect of electron withdrawing/donating groups on the stabilization of the resulting carbocation seems critical for the success of the process and was discussed in detail. Based on diamines ( 1–2 ), a series of new polyimides, (5a–5d) and (6a–6d) , were prepared, respectively. Polyimides (5a–5d) are flexible and creasable. In contrast, polyimides (6a–6d) are brittle because of the structure rigidity, according to the analysis based on the NMR temperature‐dependent spectra of ( 2 ). Polyimides 5 displaying high T_g (318–392 °C), high moduli (3.39–4.49 GPa), low coefficient of thermal expansion (42–50 ppm/°C), and moderate thermal stability (T_d 5 wt % at 426–439 °C), are excellent high‐T_g and flame‐retardant materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2486–2499, 2009     

Ultra-high Tg and ultra-low coefficient of thermal expansion polyimide films based on hydrogen bond interaction

To tolerate high processing temperature during the fabrication of low-temperature polycrystalline silicon thin-film transistors (LTPS–TFT) in flexible OLED devices, the polyimide (PI) films, which are used as substrate, should have ultra-high glass transition temperature (T_g > 450°C) and ultra-low coefficient of thermal expansion (CTE at 0–5 ppm K⁻¹). In this paper, two novel heterocyclic monomers, namely, N,N'-(xanthone-2,7-diyl)bis(4-aminobenzamide) (p-DAXBA) and N,N'-(xanthone-2,7-diyl)bis(3-aminobenzamide) (m-DAXBA), which contain a xanthone moiety, are prepared and polycondensed with pyromellitic dianhydride (PMDA), respectively. PI films (PIa and PIb) with intrinsic high T_g and low CTE are designed from the perspective of rigid conjugate xanthone structure and hydrogen bonding interaction. It is found that the PIa films prepared by p-DAXBA have better linear structure of molecular chains and show relatively higher T_g and lower CTE. The T_g of PIa-40 is greater than 450°C, and CTE can reach as low as 2.7 ppm K⁻¹, tensile strength of 179 MPa, modulus of 5.67 GPa, indicating potential application prospect as a flexible OLED substrate.     

Synthesis of novel colorless polyimides from benzimidazole diamines with various linearity

To synthesize colorless superheat-resistant polyimide films, one of the valid approaches is the incorporation of the asymmetric and warped structures in the main chain. Applying this approach on 5(6)-amino-2-(4-aminobenzene)benzimidazole (PABZ) and changing its linearity, 6, 5′-diamine-2′-methyl-1-methyl-2-phenylbenzimidazole (5a) and 6, 3′-diamine-2′-methyl-1-methyl-2-phenylbenzimidazole (5b) were devised and synthesized successfully, then polymerized with 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA). The prepared poly(benzimidazole imide)s (PBIIs) with the rigid main chain and loose packing had the excellent heat-resistant level (T_g > 400°C) and optical properties (T₄₀₀ > 80%). Besides, the alterations resulting from various linearities were discussed comprehensively. This research is beneficial to the application of optical field, providing a promising candidate of heat-resistant colorless materials.     

Study on side-chain second-order nonlinear optical polyimides based on novel chromophore-containing diamines. I. Synthesis and characterization

Side-chain second-order nonlinear optical polyimides were prepared from four novel chromophore-containing diamines and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride by a traditional two-step process that included a solution polycondensation followed by a chemical imidization. The four diamines were 2,4-di-β-aminoethylamino-6-p-nitrophenylamino-1,3,5-triazine (M1), 4-nitro-4′-[N-(4,6-di-β-aminoethylamino)-1,3,5-triazin-2-yl]amino azobenzene (M2), 2,4-di-p-aminophenylamino-6-p-nitrophenylamino-1,3,5-triazine (M3), and 4-nitro-4′-[N-(4,6- di-4-aminophenylamino)-1,3,5-triazin-2-yl]amino azobenzene (M4). All the polyimides exhibited maximum ultraviolet-visible absorption peaks or shoulders of chromophores at wavelengths below 400 nm, and those based on M1 and M3 were transparent at wavelengths above 450 nm, whereas those based on M2 and M4 were transparent at wavelengths above 550 nm. The polyimides possessed high glass-transition temperatures (T_g's; 218–247 °C) and thermal decomposition temperatures. They were soluble in aprotic solvents such as N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, N,N-dimethyl formamide, and dimethylsulfone. Some were even soluble in common low-boiling-point solvents such as tetrahydrofuran. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4330–4336, 1999     

Synthesis of soluble,thermosetting polymides derived from 1,4-phenylenebis(phenylmaleic anhydride) and aromatic diamines

The dianhydride monomer 1,4-phenylenebis(phenylmaleic anhydride) was polymerized with various aromatic diamines in a one-step solution polymerization to afford high molecular weight, soluble polyimides containing backbone phenylmaleimide structures. The polymides were soluble in amide solvents, chlorinated hydrocarbons, and tetrahydrofuran at 25°C at a concentration of 15% (w/v), displayed molecular weight distributions (M_w/M_n) of 2.0–2.2 as determined by absolute GPC and showed T_g values of 240°C and above as measured by differential scanning calorimetry. In addition, polyimide thermosets were prepared from these materials by thermal cure at 350–360°C. The crosslinked polyimides displayed T_gs 20–25°C higher than their soluble precursors, and chloroform extraction indicated gel fractions ranging from 74–100% after cure. © 1994 John Wiley & Sons, Inc.     

Synthesis and characterization of novel dipeptide mimetics with hydantoin moiety

The synthesis of three novel 5,5-dimethylhydantoin derivatives 2-amino-N-(4,4-dimethyl-2,5-dioxoimidazolidin-1-yl)acetamide, 2-amino-N-(4,4-dimethyl-2,5-dioxoimidazol idin-1-yl)-3-phenylpropanamide, and 2-amino-4-methyl-N-(4,4-dimethyl-2,5-dioxoimidazol idin-1-yl) pentanamide, is reported. The newly synthesized compounds have been characterized by infrared (IR), MS, and NMR (¹H and ¹³C) spectra.     

Effect of multiple H‐bonding on the properties of polyimides containing the rigid rod groups

To investigate the influence of hydrogen bonding on the properties of polyimides (PIs) containing rigid rod‐like groups, five symmetrical diamines containing benzimidazole, benzoxazole, and hydroxy group were synthesized, and then a series of PIs were prepared. Results showed that hydroxyl‐containing poly(benzoxazole imide)s possess higher glass transition temperature (T_g) and dimensional stabilities than their corresponding poly(benzoxazole imide)s. Moreover, the corresponding poly(benzimidazole imide)s presented the best performances, such as the highest T_g, the highest char yield and the highest dimensional stabilities. The influence of hydrogen bonding of benzimidazole on the properties of PIs was stronger than that of hydroxyl groups. Hydroxyl‐containing poly(benzoxazole imide)s were formed in crosslinking structures after heat treatment at 400 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 570–581     

Polymerization of N-(p-aminobenzoyl)caprolactam: Block and alternating copolymers of aromatic and aliphatic polyamides

The polymerization behavior of N-(p-aminobenzoyl)caprolactam was studied. It was found that polymerization could proceed by either elimination of caprolactam or by ring opening. Polymers prepared at temperatures above 200°C showed a greater tendency for ring opening to produce alternating aromatic/aliphatic copolymers than did polymers prepared at lower temperatures. Block copolymers of poly(p-benzamide) and nylon 6 were prepared by a two-stage hydrolytic polymerization process or by anionic polymerization at temperatures > 200°C. Polymer microstructures were determined using ¹³C-NMR spectroscopy by comparison with homopolymers and model alternating copolymers. The alternating copolymer prepared by condensation of N-(p-aminobenzoyl)-6-caproic acid showed a melting transition at 300–305°C in the DSC and a T_g in subsequent heating cycles of 116–119°C. Copolymers made with the two-stage process were rich in p-benzamide sequences and showed no T_g or T_m below 400°C. Copolymer made with NaH was rich in nylon 6 units, showed a T_m of 175–180°C and a T_g of 80–81°C, and was homogeneous in both the melt and solid.     

基于1,2-二氢-2-(4-羧基苯基-4-[4-(4-羧基苯氧基)-3-甲基苯基](2H)二氮杂萘-1-酮的新型芳香聚酰胺的简易合成

A new monomer diacid, 1,2-dihydro-2-(4-carboxylphenyl)-4-[4-(4-carboxylphenoxy)-3-methylphenyl]phtha-lazin-1-one (3), was synthesized through the aromatic nucleophilic substitution reaction of a readily available unsymmetrical phthalazinone 1 bisphenol-like with p-chlorobenzonitrile in the presence of potassium carbonate in N,N-dimethylacetamide and alkaline hydrolysis. The diacid could be directly polymerized with various aromatic diamines 4a-4e using triphenyl phosphite and pyridine as condensing agents to give five new aromatic poly(ether amide)s 5a-5e containing the kink non-coplanar heterocyclic units with inherent viscosities of 1.30-1.54 dL/g.The polymers were readily soluble in a variety of solvents such as N,N-dimethylformamide (DMF), N,N-dimethyl-acetamide (DMA), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidinone (NMP), and even in m-cresol and pyridine (Py). The transparent, flexible and tough films could be formed by solution casting. The glass transition tem-peratures Tg were in the range of 286-317℃.     

Aromatic polyamides. III. Copoly(4,4′-oxanilideterephthalamide—4,4′-phenyleneterephthalamide): Synthesis,wet-spinning,fiber thermal characterization,and stability in sulfuric acid

Copoly(4,4′-oxanilideterephthalamide—4,4′-phenyleneterephthalamide) (A-202/PPD) was synthesized by reaction of 4,4′-diaminooxanilide, p-phenylenediamine, and terephthaloyl chloride in organic solvents. Copolymer inherent viscosities in H₂SO₄ as high as 10.3 were obtained. Isotropic copolymer solutions (4%—5% concentration) of A-202/40%–80% PPD were spun to fibers with tenacity/elongation/modulus at 1% extension in the 13–14 gpd/1.5%–2%/700–1000 gpd range. Oxamide and amide stabilities in 98–100% H₂SO₄ and 20% oleum were compared. Poly(4,4′-oxanilideterephthalamide) (A-202), A-202/PPD copolymers, and poly(4,4′-phenyleneterephthalamide) (PPT) were unstable in 20% oleum, but all proved relatively stable in 100% H₂SO₄. However, the oxamide linkage proved less stable than the amide linkage in 98% H₂SO₄. A-202 and A-202/PPD copolymers formed stable anisotropic spinning solutions in 1% oleum at 10–20% concentrations. Dynamic mechanical analyses (Vibron) showed no glass transition temperature (T_g) below 200°C. Dilatometric measurement of A-202/50% PPD revealed a T_g at 257°C. Differential thermal analyses of A-202/40–80% PPD exhibited endotherms at 470–480°C. Thermogravimetric analyses showed no significant weight loss below 400°C.     

Facile synthesis of soluble aromatic poly(amide amine)s via C–N coupling reaction: Characterization,thermal, and optical properties

Aromatic poly(amide amine)s (APAAs), as novel high‐performance polymers, have been obtained by the condensation polymerization of N,N'‐bis(4‐bromobenzoyl)‐p‐phenylenediamine with two different primary aromatic diamines via palladium‐catalyzed aryl amination reaction. The structures of the polymers are characterized by means of FTIR, ¹H NMR spectroscopy, and elemental analysis, the results show a good agreement with the proposed structures. DSC and TGA measurements exhibit that polymers possess high glass transition temperature (T_g > 240 °C) and good thermal stability with high decomposition temperatures (T₅ > 400 °C). These novel polymers also display good solubility. In addition, due to its special structure, APAA‐2 is endowed with significantly strong photonic luminescence in N,N‐dimethylformamide and good electroactivity. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4845–4852     

Synthesis and properties of novel cardo aromatic poly(ether‐benzoxazole)s

Three new bis(ether‐acyl chloride) monomers, 1,1‐bis[4‐(4‐chloroformylphenoxy)phenyl]cyclohexane ( 1a ), 5,5‐bis[4‐(4‐chloroformylphenoxy)phenyl]‐4,7‐methanohexahydroindan ( 1b ), and 9,9‐bis[4‐(4‐chloroformylphenoxy)phenyl]fluorene ( 1c ), were synthesized from readily available compounds. Aromatic polybenzoxazoles bearing ether and cardo groups were obtained by the low‐temperature solution polycondensation of the bis(ether‐acyl chloride)s with three bis(aminophenol)s and the subsequent thermal cyclodehydration of the resultant poly(o‐hydroxy amide)s. The intermediate poly(o‐hydroxy amide)s exhibited inherent viscosities in the range of 0.35–0.71 dL/g. All of the poly(o‐hydroxy amide)s were amorphous and soluble in many organic polar solvents, and most of them could afford flexible and tough films by solvent casting. The poly(o‐hydroxy amide)s exhibited glass‐transition temperatures (T_g's) in the range of 141–169 °C and could be thermally converted into the corresponding polybenzoxazoles approximately in the region of 240–350 °C, as indicated by the DSC thermograms. Flexible and tough films of polybenzoxazoles could be obtained by thermal cyclodehydration of the poly(o‐hydroxy amide) films. All the polybenzoxazoles were amorphous and showed an enhanced T_g but a dramatically decreased solubility as compared with their poly(o‐hydroxy amide) precursors. They exhibited T_g's of 215–272 °C by DSC and showed insignificant weight loss before 500 °C in nitrogen or air. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4014–4021, 2001     

Synthesis of novel poly(aryl ether amide)s containing the phthalazinone moiety

Two novel heterocyclic diamine monomers: 1,2-dihydro-2-(4-aminophenyl)-4-[ 4-( 4-aminophenoxy) phenyl ]-(2H )-phtha-lazin-1-one and 1, 2-dihydro-2-( 4-aminophenyl )-4-[ 4-( 4-aminophenoxy) -3, 5-dimethylphenyl ] - (2H) -phthalazin-1-one were successfully synthesized using readily available heterocyclic bisphenol-like monomers through two steps in high yield. A series of novel poly( aryl ether amide)s containing the phthalazinone moiety with inherent viscosities of 1.16-1.67 dL/g were prepared by the direct polymerization of the novel diamines and aromatic dicarboxylic acids using triphenyl phosphite and pyridine as condensing agents. The polymers were readily soluble in a variety of solvents such as N, N-dimethyl-formamide (DMF), N,N-dimethylacetamide (DMAc), dimethylsulfoxide ( DMSO ), N-methyl-2-pyrrolidinone (NMP), and pyridine. The polymers had high glass transition temperatures (Tg) in the 291-329℃ range.     

Synergism and multiple mechanical relaxations observed in ternary systems based on benzoxazine,epoxy, and phenolic resins

The synergism in the glass‐transition temperature (T_g) of ternary systems based on benzoxazine (B), epoxy (E), and phenolic (P) resins is reported. The systems show the maximum T_g up to about 180 °C in BEP541 (B/E/P = 5/4/1). Adding a small fraction of phenolic resin enhances the crosslink density and, therefore, the T_g in the copolymers of benzoxazine and epoxy resins. To obtain the ultimate T_g in the ternary systems, 6–10 wt % phenolic resin is needed. The molecular rigidity from benzoxazine and the improved crosslink density from epoxy contribute to the synergistic behavior. The mechanical relaxation spectra of the fully cured ternary systems in a temperature range of −140 to 350 °C show four types of relaxation transitions: γ transition at −80 to −60 °C, β transition at 60–80 °C, α₁ transition at 135–190 °C, and α₂ transition at 290–300 °C. The partially cured specimens show an additional loss peak that is frequency‐independent as a result of the further curing process of the materials. The ternary systems have a potential use as electronic packaging molding compounds as well as other highly filled systems. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1687–1698, 2000     

Synthesis of thermosetting polyetherimide‐containing allyl groups

An allyl‐containing diphenol, 1‐(3‐allyl‐4‐hydroxyphenyl)‐1‐(4‐hydoxyphenyl)‐1‐(6‐oxido‐6H ‐dibenz[c,e][1,2]oxaphosphorin‐6‐yl)ethane (1) , was prepared from a one‐pot reaction of 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide, 4‐hydroxyacetophenone, and 2‐allylphenol in the presence of p‐toluenesulfonic acid monohydrate. Then, an allyl‐containing dietheramine, 1‐(4‐(4‐aminophenoxy)phenyl)‐1‐(3‐allyl 4‐(4‐aminophenoxy)‐phenyl)‐1‐(6‐oxido‐6H‐dibenz[c,e][1,2] oxaphosphorin‐6‐yl)ethane (3) , was prepared from the nucleophilic substitution of (1) with 4‐fluoronitrobenzene, followed by the reduction of the dinitro groups by Fe/HCl. A flexible polyetherimide (PEI) (4) with a curable characteristic was prepared from the condensation of (3) and 4,4′‐oxydiphthalic anhydride (ODPA) in m‐cresol in the presence of isoquinoline. Curing PEI (4) at 300 °C leads to PEI (5) , which exhibits much a higher T_g value (307 °C) and a lower coefficient of thermal expansion (CTE) (29 ppm/°C) than PEI (4) (T_g = 253 °C, CTE 52 ppm/°C). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis of cyclic polysulfides: Controlled ring‐expansion polymerization of cyclic tetrathioester with thiirane

We synthesized cyclic tetrathioesters containing thioester moieties at the o‐position (o‐CTE) and m‐position (m‐CTE) of an aromatic skeleton. The reaction of phenoxy propylenesulfide (PPS) with o‐CTE and m‐CTE was examined using tetrabutylammonium chloride as a catalyst in 1‐methyl‐2‐pyrrolidinone, yielding the corresponding cyclic polysulfides poly[o‐CTE(PPS)_n] with M_n's = 37,000–54,000 at 34–61% yields and poly[m‐CTE(PPS)_n] with M_n's = 46,600–107,200 at 63–>99% yields. Although the molecular weights of poly[o‐CTE(PPS)_n] could not be controlled, those of poly[m‐CTE(PPS)_n] could be controlled by the feed ratios of PPS and reaction temperature. Furthermore, the glass transition temperature (T_g) and thermal decomposition temperature (T_dⁱ) of poly[m‐CTE(PPS)_n] increased with decreasing molecular weights. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 857–866     

Chemoselective synthesis of 5-amino-7-bromoquinolin-8-yl sulfonate derivatives and their antimicrobial evaluation

Abstract

A series of new 5-amino-7-bromoquinolin-8-ol sulfonate derivatives 5(a–j) were synthesized from 8-hydroxyquinoline through multi-step process with high yields using mild, efficient and conventional methods. Chemoselectivity was observed during the transformation of 5-amino-7-bromoquinolin-8-ol to 5-amino-7-bromoquinolin-8-ol sulfonate with various sulfonylchlorides exclusively to afford sulfonate derivatives. Also, the products were investigated for their in vitro antimicrobial activities and compared with the standard drugs. Among all the synthesized compounds 5-amino-7-bromoquinolin-8-yl biphenyl-4-sulfonate (5b) and 5-amino-7-bromoquinolin-8-yl 2-hydroxy-5-nitrobenzenesulfonate (5g) have showed potent antibacterial activity, whereas 5-amino-7-bromoquinolin-8-yl biphenyl-4-sulfonate (5b) and 5-amino-7-bromoquinolin-8-yl 2-hydroxy-5-nitrobenzenesulfonate (5g) possessed potent antifungal activities among all the tested pathogens.