Synthesis of novel bismaleimide monomers based on fluorene cardo moiety and ester bond: Characterization and thermal properties

Two novel bismaleimide monomers based on fluorene cardo moiety and ester bonds, namely 9, 9-bis[4-(4-maleimidobenzoate) phenyl]fluorene (PEFBMI) and 9,9-bis[4-(4-maleimidobenzoate)-3-methylphenyl]fluorene (MEFBMI) were designed and synthesized. Their structures were confirmed by FTIR, ¹H-NMR, ¹³C-NMR spectroscopy and Elemental analysis. Both monomers obtained have excellent solubility in some organic solvents with low boiling point, including acetone, chloroform and dichloromethane. The curing process of the monomers were investigated by DSC, displaying that the melting point of the monomers were 157.1°C and 193.6°C respectively, and all processing windows exceed 30°C. DMA results showed the glass transition temperature of the cured PEFBMI/glass cloth composite was higher than 390°C while that of the cured PEFBMI composite was 349.2°C. TGA results indicated that the cured BMI resins have good thermal stability and their 5% weight loss temperatures were both higher than 410°C.     

Thermostable laminating resins based on aromatic diketone bis- and tetramaleimides

Twelve structurally different bis- and tetramaleimides were synthesized by Friedel–Crafts reaction between 4-maleimido-benzoylchloride or 3,5-bismaleimido-benzoylchloride and various aromatic reagents. They were characterized by infrared (IR) and proton nuclear magnetic resonance (¹H-NMR) spectroscopy. Crosslinked resins were obtained by curing the monomers at 250°C/6 h. Thermal characterization of monomers and cured resins was accomplished by differential thermal analysis (DTA), dynamic thermogravimetric analysis (TGA), and isothermal gravimetric analysis (IGA). Tetramaleimides were polymerized at lower temperatures than did the respective bismaleimides. The cured resins were stable up to 317–385°C in N₂ atmosphere and formed an anaerobic char yield of 52–66% at 800°C.     

Synthesis and characterization of multifunctional propenyl‐endcapped aromatic co‐monomers and their use as bismaleimide modifiers

A series of novel modifiers for bismaleimide, bearing propenyl and phenoxy functional groups has been synthesized. Structural information of the monomers was obtained through Fourier transform infrared spectroscopy (FT‐IR), nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Polymerization characteristics demonstrate that all four systems prepared have a cure temperature below 210°C. This remarkably lower cure temperature compared to that of other polymerization reactions involving diallyl bisphenol A and bismaleimide (DBMI) originates from propenyl groups being present in the structures as well as their larger free volume. The rheological behaviors leading to low melt viscosities and the wide process window of the prepolymer are particularly suitable characteristics for the production of performance resin‐based composite materials via resin transfer molding processes. The dynamic mechanical analysis of the materials reveals glass transition temperatures in a range between 260°C and 293°C. Thermal stabilities show a 5% weight loss at temperatures ranging from 363°C to 428°C with the production of char ranging from 38.5% to 57.6% at 800°C under nitrogen. The latter is a clear indication for the excellent thermal stabilities featured by the cured resins. Furthermore, the dielectric properties exhibit a significantly lower dielectric constant and dissipation factors of the propenyl‐modified cured systems compared to those of DBMI resins at 10 GHz. Copyright © 2015 John Wiley & Sons, Ltd.     

Triphenylphosphine oxide-based bismaleimide and poly(bismaleimide): Synthesis,characterization, and properties

A novel phosphorus-containing bismaleimide, 3,3′-bis(maleimidophenyl)phenylphosphine oxide (BMPPPO), was synthesized from triphenylphosphine oxide. This bismaleimide exhibited good solubility in common organic solvents, such as methylethylketone, methylisobutylketone, dichloromethane, chloroform, tetrahydrofuran, acetone, methanol, ethanol, and hot toluene. A low melting point (T_m = 148 °C), a relatively low polymerization temperature (T_p = 214 °C), and a wide processing window (T_p − T_m = 66 °C) were also obtained for BMPPPO. This implies better processing capability. In contrast to most known phosphorus-containing polymers, the incorporation of BMPPPO into poly(bismaleimide) enhanced the polymer glass-transition temperature. Thermal stability at temperatures over 550 °C and char yields in the high-temperature region over 700 °C were also improved. As a result, the flame-retardant properties of the poly(bismaleimide)s were improved. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1716–1725, 2001     

链延长型芳杂环双马来酰亚胺树脂的合成及性能

从分子结构出发,设计合成了含酞/芴Cardo环结构、1,3,4-噁二唑不对称结构共计3类10种新型链延长型双马来酰亚胺(BMI),采用核磁共振(NMR)、红外光谱(IR)、示差扫描量热仪(DSC)、热失重分析仪(TGA)、动态力学分析仪(DMA)等技术表征了BMI树脂的化学结构、固化行为以及固化物的热稳定性和动态力学性能,探讨了分子结构与性能关系.研究结果表明含酞(芴)Cardo结构BMI在普通低沸点有机溶剂中具有良好的溶解性能;含1,3,4-噁二唑结构BMI由于具有不对称分子结构导致两端官能团反应活性存在明显差异;3类BMI的固化物均具有优异耐热性和热稳定性.     

Partially biobased polymers: The synthesis of polysilylethers via dehydrocoupling catalyzed by an anionic iridium complex

Partially biobased polysilylethers (PSEs) are synthesized via dehydrocoupling polymerization catalyzed by an anionic iridium complex. Different types (AB type or AA and BB type) of monomers are suitable. Levulinic acid (LA) and succinic acid (SA) have been ranked within the top 10 chemicals derived from biomass. BB type monomers (diols) derived from LA and SA have been applied to the synthesis of PSEs. The polymerization reactions employ an air-stable anionic iridium complex bearing a functional bipyridonate ligand as catalyst. Moderate to high yields of polymers with number-average molecular weights (M_n) up to 4.38 × 10⁴ were obtained. A possible catalytic cycle via an Ir-H species is presented. Based on the results of kinetic experiments, apparent activation energy of polymerization in the temperature range of 0–10 °C is about 38.6 kJ/mol. The PSEs synthesized from AA and BB type monomers possess good thermal stability (T₅ = 418 °C to 437 °C) and low glass-transition temperature (T_g = −49.6 °C).     

Synthesis and properties of polymeric analogs of ionic liquids

A number of methacrylate ionic monomers with different structures and mobilities of ionic centers were synthesized. The free-radical polymerization of these monomers in solution affords high-molecular-mass (M _sD = 0.5 to 2.5 × 10⁶) thermally stable (T _dec > 170°C) polyelectrolytes or cationic or anionic “polymeric ionic liquids.” The conductivities of polycation- and polyanion-derived coatings are (7.4 × 10^?10)?(7.6 × 10^?7) and (4.9 × 10^?10)-(1.6 × 10^?7) S/cm (25°C), respectively. As exemplified by poly(1-[3-(methacryloyloxy)propyl]-3-methylimidazolium bis[(trifluoromethanesulfonyl)imide]), the molecular mass and glasstransition temperature of the polymer affect the ionic conductivity of the film coating. The transition from linear polyelectrolytes to crosslinked systems based on ionic monomers and poly(ethylene glycol dimethacrylate) 750 leads to the formation of elastic films featuring satisfactory strength, reduced glass-transition temperatures (?8 to +15°C), and increased ionic conductivity (up to 3.2 × 10^?6 S/cm (25°C)).     

Laminating resins obtained from 2,2′-(1,4-phenylenedivinylene)bispyridine bismaleimides and maleimide-terminated styrylpyridine prepolymers

A new bismaleimide (2a) , biscitraconimide (2b) , and bisnadimide (4) were synthesized by reacting 2-amino-6-methylpyridine with an equimolar amount of maleic, citraconic, or nadic anhydride, respectively, and then with a half molar amount of 1,4-benzenedicarbaldehyde in the presence of acetic anhydride. They, as well as the intermediate amic acids ( 1a, 1b, and 3 ) were characterized by IR and ¹H-NMR spectroscopy. The DTA thermograms showed that crosslinking of polymer precursors started at 180–212°C. The crosslinked resins obtained from 2a and 2b were stable up to 300–313°C and afforded anaerobic char yield of 53–60% at 800°C. The cured resin of 4 was less thermostable. In addition, end-capping of styrylpyridine prepolymers was accomplished by reacting 2,6-dimethylpyridine (n mol) with 1,4-benzenedicarbaldehyde (n + 1 mol) in acetic anhydride to yield a formyl-terminated styrylopyridine prepolymer. The latter reacted with the maleamic acid 1a (2 mol) to afford a series of maleimide-terminated styrylpyridine prepolymers MTSOs. They showed lower curing temperatures than did the ordinary poly(styrylpyridine). Their cured resins did not lose weight up to 310–344°C both in N₂ or air and afforded anaerobic char yield of 66-72% at 800°C.     

Synthesis of aromatic amine curing agent containing non-coplanar rigid moieties and its curing kinetics with epoxy resin

A kind of aromatic diamine, 4′, 4″-(2, 2-diphenylethene-1, 1-diyl)dibiphenyl-4-amine (TPEDA), was successfully synthesized via Suzuki coupling reaction. The TPEDA containing nonplanar rigid moieties can be used as epoxy resins curing agent to improve the complex properties of cured composites. The curing kinetics during thermal processing of E51/TPEDA system was investigated by nonisothermal differential scanning calorimeter. The average activation energy (E _α), pre-exponential factor (lnA), and reaction order (n) calculated from the Kissinger, the Ozawa, the Friedman and the Flynn–Wall–Ozawa methods were 55.8 kJ mol^?1, 9.4 s^?1 and 1.1, respectively. By the aid of estimated kinetic parameters, the predicted heat generation vs temperature curves fit well with the experimental data, which supported the validity of the estimated parameters and the applicability of the analysis method used in this work. By the introduction of nonplanar rigid moieties, the cured epoxy resins with TPEDA exhibited a higher glass transition temperature (T _g = 258 °C), good thermal stability (≈395 °C at 10 % mass-loss), and high char yield (36.6 % at 700 °C under nitrogen) compared with conventional curing agents.     

Cure mechanism of novel bismaleimide resins based on fluorene cardo moiety and their thermal properties

In this paper, two novel bismaleimide resins based on 9, 9-bis[4-(4-maleimidophenoxy) phenyl] fluorene (PFBMI), 9, 9-bis[4-(4-maleimidophenoxy)-3-methylphenyl]fluorene (MFBMI), and 2, 2’-diallyl bisphenol A (DABPA) were prepared. Their curing mechanism and curing kinetic were carefully investigated by Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The thermal mechanical properties of the composites based on these BMI resins and the glass cloth were obtained by Dynamic mechanical analysis (DMA), displaying that the novel resins whose T_g were 296°C and 289°C had excellent thermal performance. In addition, Thermogravimetric analysis (TGA) results showed that both the cured PD and MD resins possessed good thermal stability, and their T_5% were all higher than 410°C.     

Preparation of new poly(ester triazole) and poly(amide triazole) by “click chemistry”

New dialkynyl monomers containing furan and ester or amide units were prepared via three step reactions from ethyl furan-2-carboxylate. Their click polymerization with either poly(ethylene glycol) diazide or poly(tetrahydrofuran) diazide catalyzed by Cu(I) led to corresponding amorphous poly(ester triazole) and poly(amide triazole) with molecular weights in the range of (7–11) × 10³ and with glass transition temperatures in the range of ?35 and ?19°C. The temperature at 5% wt loss (T ₁₀), determined from TGA of polyazomethines were in the range 345–365°C indicating their good thermal stability.     

Benzocyclobutene in polymer synthesis. I. Homopolymerization of bisbenzocyclobutene aromatic imides to form high-temperature resistant thermosetting resins

A series of new bisbenzocyclobutene-terminated aromatic imide monomers has been synthesized from the condensation reaction of 4-aminobenzocyclobutene and the perspective dianhydride in refluxing acetic acid/toluene. The differential scanning calorimetric studies of the foregoing monomers indicated that polymerization exotherms began at 229–250°C and reached their maxima at 258–263°C. The cured samples (250–254°C; N₂; 8 h) were surprisingly stable toward thermo-oxidative degradation; only 7–10% weight loss was observed after 200 h (in air) at 314°C (600°F). At higher temperatures (650 and 700°F), the most rigid structure was the most thermo-oxidatively stable. An approach to enhance both the final glass-transition temperature (T_g cure) and the thermo-oxidative stability of the bisbenzocyclobutene system was to dilute the cure-site density since the cure-site structure is the weakest part of the polymeric structure. Therefore, a series of bisbenzocyclobutene-terminated aromatic imide oligomers were prepared, using various aromatic amines as the chain-extending agents. Meta-phenylenediamine was apparently the most effective in the advancement of both the T_g (cure) and thermo-oxidative stability.     

Synthesis and characterization of highly fluorinated poly(phthalazinone ether)s based on AB‐type monomers

Four different fluorinated methyl‐ and phenyl‐substituted 4‐(4‐hydroxyphenyl)‐2‐(pentafluorophenyl)‐phthalazin‐1(2H)‐ones, AB‐type phthalazinone monomers, have been successfully synthesized by nucleophilic addition–elimination reactions of methyl‐ and phenyl‐substituted 2‐((4‐hydroxy)benzoyl)benzoic acid with 1‐(pentafluorophenyl)hydrazine. Under mild reaction conditions, the AB‐type monomers underwent self‐condensation polymerization reactions successfully and gave fluorinated poly(phthalazinone ether)s with high molecular weights. Detailed structural characterization of the AB‐type monomers and fluorinated polymers was determined by ¹H NMR, ¹⁹F NMR, FTIR, and GPC. The solubility, thermal properties, mechanical properties, water contact angles, and optical absorption of the polymers were evaluated. The polymers had high T_gs varying from 337 to 349 °C and decomposition temperatures (T_{d, 25} wt %) above 409 °C. Tough, flexible films were cast from THF and chloroform solutions. The films showed excellent tensile strengths ranging from 70 to 85 MPa with good hydrophobicities with water contact angles higher than 95.5 °C. The polymers had absorption edges below 340 nm and very low absorbance per cm at higher wavelengths 500–2500 nm. These results indicate that the polymers are promising as high performance materials, for example, membranes and hydrophobic materials. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1761–1770     

Synthesis,Characterization and Thermal Properties of Imide-Containing Phthalonitrile Polymers

A series of novel imide-containing phthalonitrile polymers with flexible aryl ether units have been synthesized and characterized. Bisphenol monomers were synthesized by a multi-step synthesis involving a condensation reaction between aromatic aldehydes and 2,6-dimethyl phenol, respectively. The bisphenols obtained were reacted with 4-nitrophthalonitrile to form aryl ether linkage containing bisphthalonitriles. These products were hydrolyzed to tetra carboxylic acid, which were subsequently converted into corresponding dianhydrides. The obtained dianhydrides were reacted with synthesized 4-(4′-aminophenoxy) phthalonitrile by thermal imidization leading to the formation of imide-containing phthalonitrile monomers. The synthesized monomers were cured with 3.5 wt% of aromatic diamine, 4,4′-diaminodiphenylsulphone(DDS). The structure and properties of all compounds synthesized were confirmed by using elemental analysis, FT-IR, ¹H-NMR, ¹³C-NMR, DSC, TGA and rheometric studies. The cure temperatures are found to be in the range of 283–302°C, the temperature of 5% and 10% weight loss from TGA are in the range of 433–492°C in N₂ and 424–478°C in air, char yield at 800°C is 40–51%.     

Synthesis and characterization of phthalazinone containing poly(arylene ether)s via a novel N–C coupling reaction

High‐molecular‐weight poly(phthalazinone)s with very high glass‐transition temperatures (T_g's) were synthesized via a novel N–C coupling reaction. New bisphthalazinone monomers ( 7a–e ) were synthesized from 2‐(4‐chlorobenzoyl) phthalic acid in two steps. Poly(phthalazinone)s, having inherent viscosities in the range of 0.34–0.91 dL/g, were prepared by the reaction of the bis(phthalazinone) monomers with an activated aryl halide in a dipolar aprotic solvent in the presence of potassium carbonate. The poly(phthalazinone)s exhibited T_g's greater than 230 °C. polymer 8b synthesized from diphenyl biphenol and bis(4‐flurophenyl) sulfone demonstrated the highest T_g of 297 °C. Thermal stabilities of the poly(phthalazinone)s were determined by thermogravimetric analysis. All the poly(phthalazinone)s showed a similar pattern of decomposition with no weight loss below 450 °C in nitrogen. The temperatures of 5% weight loss were observed to be about 500 °C. The poly(phthalazinone)s containing 4,4′‐isopropylidenediphenol and 4,4′‐(hexafluoroisopropylidene) diphenol and diphenyl ether linkage were soluble in chlorinated solvents such as chloroform. Other poly‐(phthalazinone)s were soluble in dipolar aprotic solvents such as N,N′‐dimethylacetamide. The soluble poly(phthalazinone)s can be cast as flexible films from solution. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2481–2490, 2003     

Synthesis and Characterization of Organosoluble Polyimides Containing Pyridyl Moiety with Ether Linkages

Two novel diamine monomers, bis(4‐amino‐3,5‐dimethylphenyl)‐3‐pyridyl methane and bis(4‐aminophenoxy‐3,5‐dimethylphenyl)‐3‐pyridyl methane were synthesized. A series of pyridine containing aromatic polyimides derived from the diamines were synthesized through a typical two‐step polymerization method. Most of the polymers show good solubility in NMP, DMAc, DMF, DMSO and CHCl₃ at room temperature. These polyimides exhibit T_g in the range of 249–317°C and 10% wt loss (T₁₀) takes place in the range of 474–564°C in N₂ and 469–558°C in air. The polymers have tensile strength in the range of 88–96 MPa, elongation at break in the range of 8.5–12.5% and tensile modulus in the range of 1.5–2.1 GPa. These polyimides also have low dielectric constant (3.26–3.64 at 1 KHz and 3.24–3.61 at 10 KHz) and low moisture absorption (0.42–0.89%).     

Development and characterization of fully bio‐based polybenzoxazine‐silica hybrid composites for low‐k and flame‐retardant applications

In the present work, new classes of bio‐based polybenzoxazines were synthesized using eugenol as phenol source and furfurylamine and stearylamine as amine sources separately through solventless green synthetic process routes and were further reinforced with varying percentages (1, 3, 5, and 10 wt%) of silica (from rice husk) to attain hybrid composites. The molecular structure, cure behaviour, thermal stability, dielectric properties, and flame‐retardant behaviour of both benzoxazine monomers and benzoxazine composites were characterized using appropriate modern analytical techniques. The eugenol‐based benzoxazines synthesized using furfurylamine (FBz) and stearylamine (SBz) were cured at 223°C and 233°C, respectively. The differential scanning calorimetry (DSC) data reveal the glass transition temperatures (T_g) of FBz and SBz were 157°C and 132°C, respectively, and the maximum decomposition temperature (T_max) as obtained from thermogravimetric analysis (TGA), were found to be 464°C and 398°C for FBz and SBz, respectively. The dielectric constants for FBz and SBz obtained at 1 MHz were 3.28 and 3.62, respectively. Furthermore, varying weight percentages (1, 3, 5, and 10 wt%) of 3‐mercaptopropyltrimethoxysilane (3‐MPTMS) functionalized bio‐silica reinforced the composite materials as evidenced by their improved thermal stability and lower dielectric constant. Data obtained from thermal and dielectric studies suggested that these polybenzoxazines could be used in the form of adhesives, sealants, and composites for high performance inter‐layer low‐k dielectric applications in microelectronics.     

Bismaleimides chain-extended by imidized benzophenone tetracarboxylic dianhydride and their polymerization to high temperature matrix resins

Heat-resistant polymers were obtained by thermal polymerization of several bismaleimides or their substituted derivatives. The chain of the polymer precursors was extended by incorporation of imidized benzophenone tetracarboxylic dianhydride between the maleimide rings in order to impart a degree of flexibility in the polymers. The bismaleimides and their corresponding tetraamic acids were characterized by infrared (IR) and proton nuclear magnetic resonance (¹H-NMR) spectroscopy. The differential thermal analysis (DTA) thermograms of the monomers showed exotherms at 200–340°C attributed to the thermally induced polymerization reactions. The influence of different substituents in the maleic double bond on the curing temperature was investigated. The thermal stability of the cured resins was evaluated by thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). They were stable up to 367–433°C both in nitrogen and air atmosphere and afforded 57–68% char yield at 800°C under anaerobic conditions. The structure of the aromatic and aliphatic diamines utilized for imidization was correlated with the thermal stability of the cured resins. The bismaleimide derived from p-phenylenediamine gave the most heat-resistant resin because of its higher rigidity.     

Synthesis and characterization of siloxane resins derived from silphenylene‐siloxane copolymers bearing benzocyclobutene pendant groups

Two bis(dimethylamimo)silanes with benzocyclobutene (BCB) groups, bis(dimethylamino)methyl(4′‐benzocyclobutenyl)silane ( 2 ) and bis(dimethylamino)methyl [2′‐(4′‐benzocyclobutenyl)vinyl]silane ( 4 ), were synthesized from different synthetic routes, which were then employed to prepare two novel silphenylene‐siloxane copolymers (SiBu and SiViBu) bearing latent reactive BCB groups by polycondensation procedure with 1,4‐bis(hydroxydimethylsilyl)benzene. At elevated temperatures these copolymers were readily converted to highly crosslinked films and molding disks with network structures by polymer chain crosslinking, which followed the first‐order kinetic reaction model. The final resins of SiBu and SiViBu demonstrated excellent thermal stability with high glass transition temperatures (218 and 256 °C) and high temperatures at 5% weight loss (553 and 526 °C in N₂, 530 and 508 °C in air). After aging at 300 °C in air for 100 h, the cured resins showed weight loss lower than 4%. The films of cured SiBu and SiViBu also exhibited relatively low dielectric constants of 2.66 and 2.64, low dissipation factors of 2.23 and 2.12 × 10^?3, low water absorptions (≤0.28%), and high transparence in the visible region with cutoff wavelengths of 321 and 314 nm. Moreover, the aged films exhibited good dielectric properties and low water absorptions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7868–7881, 2008     

Synthesis and characterization of photosensitive benzocyclobutene‐functionalized siloxane thermosets

Two methylphenylsiloxane monomers with crosslinkable benzocyclobutene functionalities at the terminal positions, 1,1,5,5‐dimethyldiphenyl‐1,1,5,5‐di[2′‐(4′‐benzocyclobutenyl)vinyl]‐3,3‐diphenyltrisiloxane (BCB‐1) and 1,1,3,3‐dimethyl‐diphenyl‐1,1,3,3‐di[2′‐(4′‐benzocyclobutenyl)vinyl]disiloxane (BCB‐2) were prepared and characterized. By heating the solution of BCB‐1 and BCB‐2 in mesitylene, two partially polymerized resins of BCB‐1B and BCB‐2B with high molecular weight were also achieved. The monomers and their oligomers fully cured at temperatures above 250 °C. Cured BCB‐1 and BCB‐2 exhibited high T_g (257 and 383 °C) and good thermal stability (T_5% > 472 °C both in N₂ and in air). They also demonstrated low dielectric constants (2.69 and 2.66), low dissipation factors (2.36 and 2.23), and low water absorptions (0.20% and 0.17%). Moreover, a negative photosensitive formulation derived from BCB‐1B in combination with 2,6‐bis(4‐azidobenzylidene)‐4‐methylcyclohexanone (BAC‐M) as a photosensitive agent has been developed. The photosensitive composition, BCB‐1B containing 5 wt % BAC‐M, showed a sensitivity of 550 mJ/cm² and a contrast of 1.96 when it was exposed to a 365 nm light (i‐line) and developed with cyclohexanone at 25 °C. A fine negative image of 10 μm line‐and‐space pattern was also printed in a film which was exposed to 700 mJ/cm² of i‐line by contact‐printing mode. The negative image can be maintained without any pattern deformation in the curing process. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6246–6258, 2009