High glass transition and thermally stable polynorbornenes containing fluorescent dipyrene moieties via ring‐opening metathesis polymerization

A high‐glass‐transition‐temperature polynorbornene, poly(NBEDPY), containing chromophore groups was synthesized by ring‐opening metathesis polymerization (ROMP) using Grubbs' catalysts; poly(HNBEDPY) was obtained by the reduction of poly(NBEDPY). The glass transition temperatures (T_g) of poly(NBEDPY) and hydrogenated poly(HNBEDPY) were as high as 250 °C and 220 °C, respectively, because of the rigid dipyrene groups, which are higher than those of commercially available ring‐opened hydrogenated polynorbornenes (JSR ARTON®; 120–165 °C). The 10% weight‐loss temperatures of hydrogenated poly(HNBEDPY) and poly(NBEDPY) were up to 450 °C and 400 °C, respectively. A hydrogenated poly (HNBEDPY) film showed excellent transparency (over 91%). The photoluminescence emission spectra of poly(HNBEDPY) showed strong solvent‐polarity dependence, revealing that poly (HNBEDPY) underwent remarkable bathochromic shifts with an increase in solvent polarity. Poly(HNBEDPY) also showed remarkable fluorescent solvatochromism (blue in toluene, greenish yellow in dimethyl sulfoxide). The cyclic voltammogram of poly(HNBEDPY) film cast onto an indium tin oxide (ITO)‐coated glass substrate exhibited one reversible oxidation redox couple at 0.55 V versus Ag/Ag⁺ in acetonitrile solution. The electrochromic characteristics of poly(HNBEDPY) showed reversibility, with a color change from its green neutral form to dark red upon the application of potentials from 0 to 1.0 V. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Optical properties of a novel fluorene‐based thermally stable conjugated polymer containing pyridine and unsymmetric carbazole groups

A new diiodo monomer containing heterocyclic pyridine and carbazole groups was synthesized via Chichibabin reaction and used in the preparation of a conjugated polymer via Suzuki coupling approach. The conjugated polymer was highly soluble in common organic solvents such as NMP, THF, dichloromethane, chloroform, toluene, xylene, and benzene at room temperature. The polymer had high glass transition temperature at 191 °C and T_d10 at 434 °C in nitrogen atmosphere. The pristine polymer exhibited the UV–vis maximum absorption at 355 nm and shifted to 420 nm after protonation. The emission of the polymer in THF solution changed from the blue region with maximum peak at 400 nm to the yellow region with maximum peak at 540 nm after protonated by HCl, and the intensity of emission depended on the concentration of acid. The polymer also showed electrochromic behavior under applied voltage. The emission color of the polymer film changed from blue (435 nm) to yellow (570 nm) when 2.5 V bias voltage was applied. The polymer also exhibited write‐once and read‐many‐times (WORM) polymer memory effect with tristable states. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 991–1002, 2009     

Preparation and dielectric properties of polyimide foams containing crosslinked structures

In order to obtain cellular materials with low dielectric properties, crosslinked polyimide foams were prepared using 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), 4,4′‐oxydianiline (ODA) and 2,4,6‐triaminopyrimidine (TAP) as monomer via a poly(ester‐amine salt) precursor process. The structures of the precursors and the polyimide foams were characterized by thermogravimetric analysis (TGA) and FT‐IR, while the morphologies of the polyimide foams were viewed from scanning electron microscopy (SEM) measurements. The results revealed that the poly(ester‐amine salt) precursor containing TAP could successfully be converted to a crosslinked polyimide foam with relatively uniform cell structure. Also, the crosslinking of TAP improved the mechanical properties of foams in comparison with the non‐crosslinking systems. With increasing content of TAP, the dielectric constants of the polyimide foams decreased gradually. For the foam with TAP molar ratio at 15%, the dielectric constant was as low as 1.77 at the frequency of 10 kHz. Though the thermal resistance decreased slightly for crosslinked foams, the decomposition temperatures were still maintained above 520°C. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis and characterization of novel liquid‐crystalline copolymers containing thermally stable photochromic groups

To overcome the defects of the thermal instability of azobenzene, a series of novel photochromic, chiral, liquid‐crystalline monomers and polymers were synthesized from (+)‐camphor. The copolymerization of the photochromic monomers with comonomers was carried out. The synthesized monomers and polymers were identified with nuclear magnetic resonance, Fourier transform infrared, and elemental analysis. The composition of the copolymers was estimated with elemental analysis. The specific rotation of the chiral compounds and polymers was evaluated. The thermal stability and phases of the polymers during heating and cooling cycles were studied with differential scanning calorimetry and thermogravimetric analysis. The phases of the polymers were identified with polarized optical microscopy textures and X‐ray diffraction analysis. The distance between the layers of smectic liquid crystals was estimated from the diffraction angles. Photoisomerization of the configurational E/Z structures was investigated with an ultraviolet–visible spectrophotometer with 300‐nm ultraviolet irradiation. The thermal stability of the Z‐structural segment in the polymers was confirmed through the heating of the polymer at 70 °C for over 10 h. The photoisomerization and thermal stability of the C?C bond in the polymeric materials were demonstrated through a series of novel chiral polymers synthesized in this investigation. Both the polarity of the center part and the molecular length at the ends of the molecules were found to be necessary factors for the formation of liquid‐crystalline molecules. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2026–2037, 2007     

Novel michael addition networks containing urethane hydrogen bonding

Covalently crosslinked networks based on poly(propylene glycol) bis(acetoacetate) with either neopentyl glycol diacrylate or hydroxyethyl acrylate derivatized bis(4‐isocyanatocyclohexyl)methane (HMDI) were prepared utilizing the Michael addition reaction in the presence of catalytic quantities of diazabicyclo[5.4.0]undec‐7‐ene (DBU). These networks were prepared in the absence of solvent at 23 °C without the formation of byproducts. Mechanical and thermal analyses of the networks were performed utilizing DMA, tensile testing, and TGA. Tensile analysis revealed that the introduction of hydrogen‐bonding urethane linkages in the diacrylate segment resulted in higher tensile strengths and elongation to break compared with nonhydrogen‐bonding analogs. All crosslinked products exhibited high gel fractions and excellent thermomechanical properties. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4118–4128, 2007     

Synthesis and properties of ultralow dielectric porous polyimide films containing adamantane

A series of novel ultralow dielectric porous polyimide (PI) films containing adamantane groups was prepared via the thermolysis of polyethylene glycol (PEG) oligomers mixed into PI matrix. Scanning electron microscopy results indicated that the porous PI films showed closed pores with an average diameter of 120 ± 10 nm. Good thermal properties with 5% weight loss temperature of 499 °C in air atmosphere and glass transition temperature in excess of 310 °C were shown for porous PI films. Notably, the ultralow dielectric constant of porous PI films with 1.85 at 1 MHz was obtained and revealed via broadband dielectric spectroscopy. The effects of the chemical structure of the PI matrix and PEG content on the decomposition behavior of PEG and the performance of porous films were investigated. Wide‐angle X‐ray diffraction results indicated that the PI matrix with large d‐spacing generated weaker interactions between the PEG and PI backbone than those of PI matrix with small d‐spacing. As a result, the PEG for the PI matrix with large d‐spacing was completely decomposed. As indicated by the broadband dielectric spectroscopy results, lower dielectric porous PI films were prepared when the PEG contents in the PI matrix increased from 0 to 20 wt %. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 549–559     

Naphthalene-ring containing diamine and resulting thermally stable polyamides

A new naphthalene-ring containing diamine, bis-[4-(5-amino-naphthalene-1-yloxy)-phenyl]-methanone was prepared from reaction of 5-amino-1-naphthol with 4,4′-dichlorobenzophenone in the presence of K₂CO₃. A series of novel polyamides were prepared by direct polycondensation of the diamine with various commercially available diacid chlorides including terephthaloyl chloride, isophthaloyl chloride, adipoyl chloride, and sebacoyl chloride. All the synthesized polyamides showed good solubility in amide type solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide and they exhibited inherent viscosities in the range of 0.44-0.52 dL/g. According to the DMTA analysis, the glass transition temperatures of the polyamides were found to be 131-187 °C. Thermogravimetric analysis indicated that the polymers were stable up to 190 °C and the 10% weight loss temperatures were recorded in the range of 350-418 °C in air atmosphere.     

Synthesis of thermally stable aromatic poly(spiroorthocarbonate)s having a Cardo or bent structure

Novel poly(spiroorthocarbonate)s [poly(SOC)]s having a Cardo or bent structure were synthesized by polycondensation of several bis‐catechols having fluorene (BCFL), spirobisindane (BCSPI), or spirobischromane (BCSPC) in the structure with 2,2,6,6‐tetrachlorobenzo[1,2‐d:4,5‐d’]bis[1,3]dioxole (4ClBD). Synthesis of poly(SOC)s was confirmed by NMR and IR spectrometry. The poly(SOC)s obtained from BCFL or BCSPC were soluble in common organic solvents. The glass transition temperature of the poly(SOC)s was not detected by differential scanning calorimetry (DSC) in the range of 50–300 °C. The 10 wt % decomposition temperature of the poly(SOC)s was found to be above 400 °C. These results indicated the high thermal stability of the poly(SOC)s. Soluble poly(SOC)s could be possessed to form a film on a glass plate by the spin coat method. The obtained polymer films were 0.2 μm in thickness with 95% light transmission in the optical wavelength range. These results suggested that the Cardo or bent structure may block the packing of the main‐chain of the structure, which improves the solubility of the polymers, increases transparency, and enhances the thermal stability of SOCs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1409‐1416     

Development of novel cardo‐containing phenylethynyl‐terminated polyimide with high thermal properties

A phenylethynyl‐terminated reactive diluent [Card‐4‐phenylethynylphthalic anhydride (PEPA)], which contained fluorenyl cardo structures, was successfully synthesized and used as a modifier for flexible phenylethynyl‐terminated imide oligomer (PEI‐PEPA). The chemical structure, crosslink characterization, molecular weights, and thermal properties of the products were characterized. The imide systems with addition of 10, 20, 30, and 40 wt% Card‐PEPA to PEI‐PEPA (PEI‐PEPA‐Card) and their cured resin systems were prepared. The thermal curing behaviors of imide systems at different heating rates were analyzed by using differential scanning calorimetry. Thermal properties such as glass transition temperature (T_g) and char yield at 800°C of the resultant resin systems were studied by differential scanning calorimetry, dynamic mechanical analysis, and thermogravimetric analysis. The rheological properties were also investigated using a dynamic rheometry. These properties were found to be outstanding compared with pure PEI‐PEPA. The uncured imide systems exhibited lower T_g and lower isothermal viscosity with addition of Card‐PEPA. Furthermore, the T_g and char yield of the cured resin systems increased with addition of Card‐PEPA. The cured resin systems containing 40 wt% Card‐PEPA exhibited the highest T_g of 359°C and char yield at 800°C of 66.5%. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of transparent and thermally stable polycyanurates and their thermal rearrangement

Transparent and thermally stable polycyanurates, whose solubility can be changed by thermal rearrangement, have been synthesized as functional films used in the multilayer coating process. Before the synthesis of polycyanurates, the model compound, 2,6‐bis(4‐methoxyphenyl)?6‐methoxy‐1,3,5‐triazine as a cyanurate is prepared and rearranged to an isocyanurate, 1,3‐bis(4‐methoxyphenyl)?5‐methyl‐1,3,5‐triazinane‐2,4,6‐trione in an excellent yield by thermal treatment. Based on this result, polycyanurates are prepared by the phase‐transfer‐catalyzed polycondensation of 2,4‐dichloro‐6‐methoxy‐1,3,5‐triazine with bisphenol monomers in the presence of quaternary ammonium salts. The polycyanurate obtained from 9,9‐bis(hydroxyphenyl)fluorene exhibits a high glass transition temperature at 251 °C. The solubility of polycyanurate films containing 1 wt % of tetrabutylammonium bromide can be changed by thermal rearrangement. The partially rearranged films keep high transparency and low birefringence. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3950–3955     

Melt-processable oligoamides having internal acetylene groups in the backbone,and thermally stable polyamides therefrom

Aromatic oligoamides of DP = 5 and 11 that have all meta-phenylene linkages were prepared by controlling the ratio of isophthaloyl chloride and diamines [m-phenylenediamine and bis(3-aminophenyl)acetylene], and then end-capped with aniline or 2-aminobiphenylene. Aromatic oligoamides having para-phenylene linkages were also prepared similarly using terephthaloyl chloride as a monomer. The oligoamides that have all m-phenylene linkages were soluble in organic solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide, though the oligoamides having p-phenylene linkages were much less soluble. The oligoamides having acetylene units in the backbone showed exotherm due to crosslinking. The onset of the exotherm appeared at 310-340°C for the oligoamides having all m-phenylene linkages, and 330-370°C for the oligoamides having p-phenylene linkages. They were melt-processed at 350 or 380°C for 1 h, giving tough and insoluble films from oligoamides having all m-phenylene linkages and brittle films from oligoamides having p-phenylene linkages. The films showed excellent thermal properties. For example, viscoelastic analyses showed little decrease of mechanical property up to 370°C, and T_g was not observed below the temperature. Thermogravimetric analyses also showed that thermal stability of the melt-processed films were excellent. © 1992 John Wiley & Sons, Inc.     

Crosslinkable aromatic polyimides containing 2,3-dicyanopyrazine rings

New crosslinkable aromatic polyimides were synthesized from 2,3-dicyano-5,6-di(aminophenyl)pyrazine ( 1b ) and 2,3-dicyanopyrazino [5,6–9,10] diaminophenanthrene ( 2b ). They were characterized by viscosimetry, IR, NMR, x-ray, DTA, TMA, TGA, and isothermal gravimetric analysis. The polyimides derived from 1b were amorphous whereas those prepared from 2b showed microcrystalline or crystalline character. The polymers were soluble in polar aprotic solvents (DMF, NMP, DMSO) at ambient temperature or upon heating. They dissolved also completely or partially in certain hot inorganic and organic acids (H₂SO₄, CCl₃COOH). Their glass transition temperatures were in the range of 257–370°C. The crosslinked polymers obtained after an appropriate thermal treatment, were stable up to 397–426°C in N₂ or air and afforded anaerobic char yields of 62–75% at 800°C. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1303–1311, 1997     

Synthesis and characterization of thermally stable and flame retardant hexakis(4-aminophenoxy)cyclotriphosphazene-based polyimide matrices

A new approach to the preparation of hexakis(4-aminophenoxy)cyclotriphosphazene (HACTP) based polyimide (PI) matrices is proposed, for improved thermal and flame retardant properties. HACTP was synthesized with good yield. The structure of HACTP was confirmed by various characterization techniques, such as FTIR, NMR, and mass Spectroscopy. Polyimide matrices were prepared by thermal imidization process using HACTP and dianhydrides using N-methyl pyrrolidone as a solvent. The successful formation of HACTP-based polyimide matrices was confirmed by the FTIR. Thermal properties of the PI were analyzed using DSC and TGA techniques. Data obtained from the thermal studies indicate that the HACTP-based PI possesses better thermal and flame retardant properties.     

Soluble and fusible polyamides and polyimides containing pyrazoline moieties and their crosslinking to heat-resistant resins

3-(4-Aminophenyl)-5-(3-aminophenyl)-2-pyrazoline as well as the 1-acetyl- or 1-benzoyl-substituted derivatives of this compound were synthesized and used for preparing a new series of polyamides and polyimides. Characterization of polymers was accomplished by inherent viscosity, ¹H-NMR, ¹³C-NMR, x-ray, DTA, TMA, TGA, and isothermal gravimetric analysis. The properties of polymers were correlated with their chemical structures. They were amorphous or microcrystalline and soluble in polar aprotic solvents, CCl₃COOH, and m-cresol. The polyamides showed an excellent solubility being soluble even in o-dichlorobenzene, 1,2-dichloroethane, and chloroform. The polymers displayed T_g at 127–163°C and softening at 150–195°C. The polyamide bearing unsubstituted pyrazoline moieties was remarkably more hydrophilic than those containing 1-acetyl- or 1-benzoyl-substituted pyrazoline segments. Upon curing, crosslinked polymers were obtained and their thermal stability was evaluated. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1353–1361, 1997     

Synthesis and properties of a novel high temperature pyridine‐containing phthalonitrile polymer

A novel pyridine‐containing aromatic phthalonitrile monomer, 2,6‐bis[4‐(3,4‐dicyanophenoxy)benzoyl]pyridine (BCBP) was synthesized from the nitro displacement of 4‐nitrophthalonitrile by the phenoxide of 2,6‐bis (4‐hydroxybenzoyl)pyridine (BHBP). 4‐(Aminophenoxy) phthalonitrile (APPH) was selected to promote the curing reaction, and the curing behavior has been investigated by differential scanning calorimetric (DSC), suggesting a wide processing window about 64 °C. Different curing additive concentrations resulted in polymers with different crosslinking degrees and subsequently influenced the performance of resins. The resulting BCBP polymer exhibited high glass transition temperatures exceeding 400 °C, outstanding thermo‐oxidative stability with weight retention of 95% at 530 °C, indicating a significant improvement in thermal properties endowed by pyridine units. Additionally, it also showed a lower overall water absorption after submersion in boiling water for 50 hours. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3819–3825     

Cationic ring‐opening polymerization of novel 1,3‐dehydroadamantanes with various alkyl substituents: Synthesis of thermally stable poly(1,3‐adamantane)s

Cationic ring‐opening polymerizations of 5‐alkyl‐ or 5,7‐dialkyl‐1,3‐dehydroadamantanes, such as 5‐hexyl‐ ( 4 ), 5‐octyl‐ ( 5 ), 5‐butyl‐7‐isobutyl‐ ( 6 ), 5‐ethyl‐7‐hexyl‐ ( 7 ), and 5‐butyl‐7‐hexyl‐1,3‐dehydroadamantane ( 8 ), were carried out with super Brønsted acids, such as trifluoromethanesulfonic acid or trifluoromethanesulfonimide in CH₂Cl₂ or n‐heptane. The ring‐opening polymerizations of inverted carbon–carbon bonds in 4–8 proceeded to afford corresponding poly(1,3‐adamantane)s in good to quantitative yields. Poly( 4–8 )s possessing alkyl substituents were soluble in 1,2‐dichlorobenzene, although a nonsubstituted poly(1,3‐adamantane) was not soluble in any organic solvent. In particular, poly( 8 ) exhibited the highest molecular weight at around 7500 g mol^?1 and showed excellent solubility in common organic solvents, such as THF, CHCl₃, benzene, and hexane. The resulting poly( 4–8 )s containing adamantane‐1,3‐diyl linkages showed good thermal stability, and 10% weight loss temperatures (T₁₀) were observed over 400 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4111–4124     

Synthesis of novel polyaryl(ether–ketones) with tert-butyl pendent groups

Linear polyaryl(ether ketones) containing tert-butyl pendent groups were prepared from aromatic hydrocarbons and aromatic diacid chlorides, both classes of monomers containing tert-butyl pendent groups. The polymers were prepared in high yield and high molecular weight by low-temperature precipitation polycondensation in 1,2-dichloroethane. The presence of meta-oriented moieties and bulky pendent groups played a beneficial role with regard to solubility, while the thermal transitions and thermal resistance were not greatly impaired relative to conventional all para-oriented polyaryl(ether–ketones). The current polyaryl(ether–ketones) showed glass transition temperatures in the range 170–240°C and decomposition temperatures, as measured by TGA, of about 500°C. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1251–1256, 1998     

New thermally stable condensation polymers containing central ketal moieties derived from malonaldehydetetramethyl acetal and dihydroxyaromatic compounds

Abstract

A number of new condensation polymers with acetal units in the main chain and having linear and ladder-form structure and high thermal stability were synthesized by solution polycondensation of dihydroxyaromatic compounds with malonaldehydetetramethyl acetal as a reactive protected 1,3-dicarbonyl compound. Optimal conditions for polycondensation were obtained via study of the model compounds. In order to obtain high molecular weight polymers, general investigations on the influence of reaction conditions, such as monomer concentration and reaction temperature were carried out. All polymers were obtained in high yields and moderate inherent viscosity ranging from 0.25 to 0.41?dL/g. The proposed chemical structures of condensation polymers were confirmed by ¹H-NMR, ¹³C-NMR, FTIR spectroscopies, TGA, and DSC. Thermal analysis indicated that these polymers are stable up to 360?°C, and a 10% weight loss (T₁₀) were recorded on the TG curves in the temperature range of 381–411?°C in nitrogen atmosphere, indicating their good thermal stability.     

Aromatic poly(sulfone sulfide amide imide)s as new types of soluble thermally stable polymers

A new diamine monomer containing flexible sulfone, sulfide, and amide units was prepared via three steps. Nucleophilic chloro displacement reaction of 4‐aminothiophenol with 4‐nitrobenzoyl chloride in the presence of propylene oxide afforded N‐(4‐mercapto‐phenyl)‐4‐nitrobenzamide and subsequent reduction of the nitro intermediate led to 4‐amino‐N‐(4‐mercapto‐phenyl)benzamide. Two moles of this amino thiophenol compound was reacted with bis‐(4‐chloro phenyl)sulfone to provide a novel diamine monomer. The diamine was reacted with aromatic dianhydrides to form polyimides via a two‐step polycondensation method, formation of poly(amic acid)s, followed by chemical imidization. The resulting polymers were characterized and their physical properties including thermal behavior, thermal stability, solubility and inherent viscosity were studied. Copyright © 2007 John Wiley & Sons, Ltd.     

A rigid, chiral, dendronized polymer with a thermally stable, right-handed helical conformation

First- and second-generation dendronized polymethacrylates PG1 and PG2 carrying chiral 4-aminoproline-based dendrons were obtained on the half-gram scale in high molar masses (PG1: M(n)=5 x 10(6) g mol(-1), PG2: M(n)=1x10(6) g mol(-1)) by spontaneous (radical) polymerization of the corresponding vinyl macromonomers. NMR spectroscopic studies on PG2 together with its unprecedented high glass transition temperature (T(g)>200 degrees C, decomp) and structural parameters provided by atomistic MD simulations show this polymer to be rather rigid. Optical rotation and CD measurements revealed that PG2 adopts a helical conformation that remains unchanged over wide ranges of temperature and solvent polarity. It is also retained when the polymer is deprotected (and thus positively charged, de-PG2) at its terminal amino groups, by which the mass and steric demand of the dendrons is reduced by roughly 50 %. Molecular dynamics simulations on models of PG2 reveal its helical conformation to be right-handed, irrespective of backbone tacticity, and initial results also indicate that de-PG2 retains the right-handedness.