Synthesis of bisphenol A‐free oligomeric phthalonitrile resins with sulfone and sulfone‐ketone containing backbones

Two new oligomeric sulfone and sulfone‐ketone containing phthalonitrile (PN) resins with excellent processability have been developed. The PN monomers were prepared from the reaction of an excess amount of bisphenol S with 4‐(chlorophenyl)sulfone or 4,4‐dichlorobenzophenone in the presence of a base in a solvent mixture (dimethylsulfoxide/toluene), followed by end‐capping with 4‐nitro‐PN in a two‐step, one‐pot reaction. These PN resins exhibited good viscosities and cure times for molding into various shapes. After being thermally cured to yield crosslinked polymers, these polymers demonstrated superb mechanical properties, thermo‐oxidative stability, and maintained good dielectric properties. Published 2016. 1 J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1639–1646     

Preparation and properties of epoxy/amine hybrid resins from in situ polymerization

Homogeneous and transparent epoxy/amine hybrid resins were successfully obtained through the in situ curing of bisphenol A epoxy and hexakis(methoxymethyl)melamine with 2 wt % (3‐glycidoxypropyl)trimethoxysilane as a facial coupling agent. The hybrid resins showed good miscibility, high glass‐transition temperatures, good thermooxidative stability, and good flame retardance. The outstanding properties of the hybrid resins may lead to their use in high‐performance green electronic products. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1868–1875, 2004     

Synthesis and characterization of new poly(arylene ether)s containing heterocyclic units. II.

A series of new poly(arylene ether)s, containing naphthalene, pyridine, and quinoline units have been prepared by solution condensation polymerization. The synthesis involves nucleophilic displacement of aromatic dihalides with aromatic potassium bisphenates in an anhydrous dipolar aprotic solvent at elevated temperatures. The polymers, having inherent viscosity from 0.24 to 1.32 dL/g, were obtained in quantitative yield, have excellent thermal stability as shown by 10% weight loss temperatures in nitrogen and air (above 450 and 430°C, respectively) and high glass transition temperatures (in the range of 150–220°C). The introduction of quinoline moieties in the polymer backbone positively influences the thermal properties, such as high T_g/T_m ratios. © 1995 John Wiley & Sons, Inc.     

Improved thermosets obtained from cycloaliphatic epoxy resins and γ‐butyrolactone with lanthanide triflates as initiators. I. Study of curing by differential scanning calorimetry and Fourier transform infrared

3,4‐Epoxycyclohexylmethyl 3,4‐epoxycyclohexane carboxylate was cured with different proportions of γ‐butyrolactone with lanthanum, samarium, and ytterbium triflates as catalysts. The curing was studied with differential scanning calorimetry (DSC) and Fourier transform infrared in the attenuated‐total‐reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and to quantify the evolution of the epoxide, lactone, and intermediate spiroorthoester groups. The glass‐transition temperature of the crosslinked materials was high and increased when the proportion of lactone decreased. The kinetics were studied with DSC experiments and were analyzed with isoconversional procedures. The differences in the reactivities of the systems were related to the Lewis acidity of the lanthanide salt used as the initiator. An increase in the proportion of lactone produced an increase in the reaction rate. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2337‐2347, 2005     

Synthesis and thermal properties of thermosetting bis-benzocyclobutene–terminated arylene ether monomers

A series of new bis-benzocyclobutene-endcapped arylene ether monomers was prepared and characterized. Whereas 2,6-bis(4-benzocyclobutenyloxy)benzonitrile (BCB-EBN) could be prepared in good yield using the standard procedure (K₂CO₃/NMP/toluene/Dean–Stark trap/120°C), other bis(benzocyclobutene) (BCB)-terminated monomers containing ether-benzophenone (BCB-EK), ether-phenylsulfone (BCB-ES), and ether-6F-benzoxazole (BCB-EBO) moieties were invariably contaminated by mono-endcapped products under similar reaction conditions. This can be attributed to a much greater activating effect of the nitrile group on the ortho-fluorides in the aromatic nucleophilic displacement reaction than the carbonyl, sulfonyl, and benzoxazolyl groups. However, the latter monomers could be synthesized (70–80%) from 4-trimethylsiloxybenzocyclobutene and respective aromatic fluorides in the presence of CsF at 140°C. Similar curing behaviors under N₂ (DSC: extrapolated onset and peak temperatures at 227–230° and 260–262°C, respectively) characterized all four monomers. BCB-EK, BCB-ES, and BCB-EBN showed melting transitions at 108, 119, and 146°C, in that order. As BCB-EBO contained more rigid benzoxazole segments, it only exhibited a glass transition (T_g) at 85°C prior to curing exotherm, after it had been previously heated to 125°C. The following T_gs were observed for the cured materials: BCB-EK (201°C), BCB-EBN (224°C), BCB-ES (264°C), and BCB-EBO (282°C). The relative thermal stability according to TGA (He) results is: BCB-ES < BCB-EBN < BCB-EK < BCB-EBO. Finally, the results from thermal analysis, infrared spectroscopic, and variable temperature microscopic studies indicated that the nitrile group plays an important role in the cure chemistry, thermal, and microstructural properties of BCB-EBN. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2637–2651, 1998     

Novel UV-curable and alkali-soluble resins for light-shielding black matrix application

A carbon black (CB) photo resist, comprising CB, CB dispersant, photo-curable resin, photo-initiator, and solvent, has been developed in order to prepare a light-shielding black matrix (BM) in the liquid crystal display application. In order to prepare a BM with a high opacity property or optical density (OD), the effect of CB such as its particle and concentration on light absorption property was first evaluated, and the results showed that 45 wt% CB with a particle size of about 100 nm in BM could reach an OD value of 4 μm⁻¹. Moreover, six different UV-curable and alkali-soluble resins (A1, A2, and A3; B1, B2, and B3) were synthesized as photo-curable resins. Structures of these resins were characterized by FTIR and GPC, in which concentrations of various functional groups, especially carboxylic acid and double bond, were calculated. Subsequently, their photo-initiated polymerization rate with or without CB were measured. Finally, it was found that through a proper selection of the newly synthesized resins to prepare a carbon black photo resist, a BM with an OD of 4 μm⁻¹ and a good resolution of 10 μm was successfully prepared upon low UV irradiation energy of 50 mJ/cm².     

Physical gelation of water‐borne thermosetting resins by percolation theory—Urea‐formaldehyde,melamine‐urea‐formaldehyde,and melamine‐formaldehyde resins

Percolation and effective‐medium theories are applied for calculating the connectivity threshold of colloid particles of given shapes, observed during the physical gelation, distinguished from chemical gelation, of aminoplastic resins. The rigidity threshold, being the critical solid fraction at which a rigid network is first formed, was also calculated. For that purpose, it was assumed that the central forces that act between the colloidal particles and aggregates were not alone, thus corresponding to the case of physical gelation. It was shown that the observed change of morphology exhibited by such particles and aggregates as a function of time, from elongated to spherical, significantly delays the gel point. Consequently, the latter occurs only after a rather high fraction of solid phase (typically from 30 to 60%) is formed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 971–978, 2008     

Synthesis and characterization of microencapsulated dicyclopentadiene with melamine–formaldehyde resins

Microcapsules containing healing agents have been used to develop the self-healing polymeric composites. These microcapsules must possess special properties such as appropriate strength and stability in surrounding medium. A new series of microcapsules containing dicyclopentadiene (DCPD) with melamine–formaldehyde (MF) resin as shell material were synthesized by in situ polymerization technology. These microcapsules may satisfy the requirements for self-healing polymeric composites. The chemical structure of microcapsule was identified by using Fourier transform infrared (FTIR) spectrometer. The morphology of microcapsule was observed by using optical microscope (OM) and scanning electron microscope. Size distribution and mean diameter of microcapsules were determined with OM. The thermal properties of microcapsules were investigated by using thermogravimetric analysis and differential scanning calorimetry. Additionally, the self-healing efficiency was evaluated. The results indicate that the poly(melamine–formaldehyde) (PMF) microcapsules containing DCPD have been synthesized successfully, and their mean diameters fall in the range of 65.2∼202.0 μm when the adjusting agitation rate varies from 150 to 500 rpm. Increasing the surfactant concentration can decrease the diameters of microcapsules. The prepared microcapsules are thermally stable up to 69 °C. The PMF microcapsules containing DCPD can be applied to polymeric composites to fabricate the self-healing composites.     

Synthesis, characterization and evaluation of sulfonic resins as catalysts

Ion-exchange resins have been often used as catalysts especially those based on styrene-divinylbenzene copolymers with sulfonic acid groups in the aromatic rings of polymer chains. That is due to the advantages of heterogenous catalysis over the homogeneous acid catalysis. Moreover, resin catalysts can often lead to high selectivity in organic reactions due to the matrix effects. Therefore, the study of copolymers synthesis conditions to determine the type of polymer structure produced as well as the characterization of sulfonic resins obtained thereof are of great interest. The current paper describes the synthesis, characterization and evaluation as catalysts of sulfonic resins derived from polymer supports synthesized by aqueous suspension polymerization of styrene and divinylbenzene. The reaction conditions were varied and polymer supports with different physical properties and morphological characteristics were obtained. The polymer supports were chemically modified by sulfonation. The resultant sulfonic resins had their catalyst activity evaluated in the esterification of acetic acid with n-butanol.     

Preparation,characterization, and polymerization of maleimidobenzoxazine monomers as a novel class of thermosetting resins

New series of benzoxazine‐based monomers, namely maleimidobenzoxazines, were prepared with hydroxyphenylmaleimide, formalin, and various amines (e.g., aniline, allylamine, and aminophenyl propargyl ether). The structure of the novel monomers was confirmed by IR, ¹H NMR, and elemental analysis. The monomers were easily dissolved in many common organic solvents. Differential scanning calorimetry of the novel monomers showed exotherms at different temperature ranges that corresponded to the polymerization regime of benzoxazine and maleimide along with other functionalities such as allyl or propargyl, if any. IR was studied to follow the progress of the curing reaction of maleimidobenzoxazine after various thermal treatments. The thermal cure of the monomers at 250 °C afforded a novel network structure that combined polybenzoxazine and polymaleimide. The dynamic mechanical analyses showed that the storage moduli of the thermosets derived from maleimidobenzoxazine were kept constant up to high temperatures. The glass‐transition temperatures were as high as 241–335 °C. Moreover, thermogravimetric analyses revealed that the thermosets did not show any weight loss up to about 350 °C, with char yields ranging from 62 to 70% at 800 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1424–1435, 2006     

Silicon-containing flame retardant epoxy resins: Synthesis, characterization and properties

Epoxy resins with different silicon contents were prepared from silicon-containing epoxides or silicon-containing prepolymers by curing with 4,4′-diaminodiphenylmethane. The reactivity of the silicon-based compounds toward amine curing agents was higher than that of the conventional epoxy resins. The T_g of the resulting thermosets was moderate and decreased when the silicon content increased. The onset decomposition temperatures decreased and the char yields increased when the silicon content increased. Epoxy resins had a high LOI value, according to the efficiency of silicon in improving flame retardance.     

Preparation and characterization of multifunctional maleimide macromonomers and their cured resins

Multifunctional compounds with pendent and terminal maleimide groups were prepared through the reaction of 4‐maleimidobenzoic acid and 5‐maleimidoisophthalic acid with diglycidyl ether of bisphenol A. The ratios of the pendent maleimide groups to the terminal maleimide groups in the obtained compounds were varied to tailor the chain length and properties of the maleimide compounds. The maleimide group ratios, determined from differential scanning calorimetry, showed good coincidence with the values calculated from the charged monomer amounts. The good solubility and low softening points of the maleimide compounds indicated their good processability. High glass‐transition temperatures (220 °C) were observed for the cured resins because of the relatively high crosslinking density. The curing reaction, thermal stability, and degradation behavior of the resins were also studied with differential scanning calorimetry and thermogravimetric analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3178–3188, 2004     

Synthesis and characterization of novel bisphthalonitrile resins linked by different molecular weight main-chain polybenzoxazines

A series of novel type bisphthalonitriles with different molecular weight main-chain polybenzoxazines as linkages have been successfully synthesized using 4, 4′-diaminodiphenyl methane, paraformaldehyde, bisphenol A and 4-nitrophthalonitrile as initial materials. The structures were characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (¹H-NMR). The formation of benzoxazine and the existence of nitrile groups were confirmed by the absorbance at 950cm^?1 of benzene attached with oxazine ring and 2231 cm^?1 of nitrile groups. The characteristic resonance peaks observed at about 4.52 (C-CH₂-N) and 5.28 ppm (N-CH₂-O) also determined the structure of benzoxazine ring. The curing behaviors were monitored by differential scanning calorimetry (DSC) and FT-IR. Two-stage polymerization mechanisms were observed according to the ring-opening of benzoxazine and the polymerization of nitrile groups catalyzed by phenolic hydroxyl groups, which generated during the curing reaction of benzoxazine. The polymerization of these bisphthalonitriles exhibited self-promoted curing behaviors. The completion of polymerization was proved by the disappearance of the band located at 950 cm^?1 in FT-IR. Thermogravimetric analysis (TGA) was used to investigate the thermal stability, and the results showed that the cured polymers achieved extremely high char yield from 61.1% up to 74.2% at 800°C under nitrogen and exhibited increasing decomposition temperature as the contents of phthalonitrile groups increased, which indicated that the polymerization of phthalonitriles could improve the thermal stability.     

Synthesis and characterization of a novel AB2 monomer and corresponding hyperbranched poly(arylene ether phosphine oxide)s

A novel AB₂ monomer, 4‐(fluorophenyl)‐4′,4″‐(bishydroxyphenyl) phosphine oxide, was synthesized. The monomer was successfully polymerized to a modest molecular weight with various catalysts, including K₂CO₃ and Cs₂CO₃/Mg(OH)₂. Hyperbranched polymers exhibited exceptionally high thermal stability and solubility in conventional polar organic solvents and basic water solutions. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3736–3741, 2000     

Synthesis and characterization of polyimides endcapped with phenylethynylphthalic anhydride

The synthesis of high glass transition temperature (T_g > 300°C), amorphous, soluble, poly-imide oligomers of controlled molecular weight endcapped with 4-phenylethynylphthalic anhydride endcapping agent is described. The 4-phenylethynylphthalic anhydride was employed to afford a higher curing temperature (380–420°C) which widens the processing window compared to unsubstituted acetylene-endcapped polyimides. The polyimides were synthesized via solution imidization techniques, using the ester-acid of various dianhydrides and aromatic diamines. A “ one-pot” procedure utilizing NMP as the solvent and o-dichlo-robenzene as the azeotroping agent reproducibly produced fully imidized, but yet soluble wholly aromatic polyimides. Thermally cured samples were prepared with gel contents of up to 98% that displayed good solvent resistance. Glass transition temperatures comparable to high molecular weight linear analogs were produced. These polyimides also show excellent thermal stability as judged by thermogravimetric analysis (TGA). Model phenylethynyl imide compounds were synthesized and used to follow and elucidate the nature of the products formed from the phenylethynyl curing by using high temperature magic-angle ¹³C nuclear magnetic resonance (MAS NMR). Preliminary results indicate that the cure reaction can be followed by MAS NMR. However, the nature of the products being formed during the curing process is difficult to determine by the solid-state MAS NMR alone. Differential scanning calorimetry (DSC) data clearly show that the model system does indeed melt and displays a wide window before the strong cure exotherm is observed. © 1995 John Wiley & Sons, Inc.     

The effect of network architecture on the thermal and mechanical behavior of epoxy resins

The effects of crosslink functionality (f_c), molecular weight between crosslinks (M_c), and chain stiffness display on the thermal and mechanical behavior of epoxy networks are determined. Both f_c and M_c are controlled by blending different functionality amines with a difunctional epoxy resin. Chain stiffness is controlled by changing the chemical structure of the various amines. In agreement with rubber elasticity theory, the rubbery moduli are dependent on f_c and M_c, but independent of chain stiffness. The glassy moduli and secondary relaxations of these networks are relatively independent of f_c, M_c, and chain stiffness. However, the glass transition temperatures (T_g) of these networks are dependent on all three structural variables. This trend is consistent with free volume theory and entropic theories of T_g. f_c, M_c, and chain stiffness control the yield strength of these networks in a manner similar to that of T_g and is the result that both properties involve flow or relaxation processes. Fracture toughness, as measured by the critical stress intensity factor (K_Ic), revealed that f_c and M_c are both critical parameters. The fracture behavior is the result of the fracture toughness being controlled by the ability of the network to yield in front of the crack tip. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1371–1382, 1998     

Synthesis, characterization, and cure properties of phosphorus-containing epoxy resins for flame retardance

An organophosphorus compound, 10-(2,5-dihydroxyl phenyl)-9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DHPDOPO), was synthesized through the reaction of 9,10-dihydro-9-oxa-10-phosphaphnanthrene-10-oxide (DOPO) and p-benzoquinone, and characterized by elemental analysis, Fourier transform infrared spectrum (FTIR), and ¹H-NMR and ³¹P-NMR spectroscopes. Consequently, the phosphorus-containing epoxy resins with phosphorus content of 1 and 2 wt.% were prepared via the reaction of diglycidyl ether of bisphenol-A with DHPDOPO and bisphenol-A, and confirmed with FTIR and gel permeation chromatography (GPC). Phenolic melamine, novolak, and dicyanodiamide (DICY) were used as curing agents to prepare the thermosetted resins with the control and the phosphorus-containing epoxy resins. Thermal properties and thermal degradation behaviors of these the thermosetted resins were investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Phenolic melamine-cured resins exhibited higher glass transition temperatures than the other cured resins due to the high rigidity of their molecular chain. TGA studies demonstrated that the decomposition temperatures of the novolak-cured resins were higher than those of the others. A synergistic effect from the combination of the phosphorus-containing epoxy resin and the nitrogen-containing curing agent can result in a great improvement of the flame retardance for their thermosetted resins.     

Thermal and electrical behavior of hybrid thermosets based on epoxy and maleimide resins cured with p-aminobenzoic acid

Two thermoset systems based on maleimides and diglycidyl ether of bisphenol A (DGEBA) cured with p-aminobenzoic acid were characterized in terms of thermal and electrical behavior. Thermal characterization has been undertaken by means of thermogravimetric analysis in nitrogen atmosphere up to 600°C using simultaneous thermogravimetric/Fourier transform infrared/mass spectrometry (TG/FT-IR/MS) analysis. In the first stage of thermal degradation, the global kinetic parameters [activation energy (E_a) and preexponential factor (log A₁ (s⁻¹))] were calculated using the isoconversional method of Friedman. The energies variation as well as the shape of the differential thermal analysis curves suggests that the thermal decomposition process occurred in multiple stages. The evolved gases analysis was conducted by simultaneous TG/FT-IR/MS coupled techniques. Dielectric relaxation spectroscopy characterization was also made.     

Synthesis and characterization of an adipic acid–derived epoxy resin

Adipic acid, a highly abundant chemical that can be produced from biomass, was used to prepare an aromatic‐free epoxy resin. Synthesis of the diglycidyl adipate was performed by a one‐step process using epichlorohydrin and by a two‐step process comprising allylation and epoxidation. The viscosity of diglycidyl adipate is 25 mPa·s, which is 99% lower than the diglycidyl ether of bisphenol A (DGEBA). The storage modulus at 25 °C for cured diglycidyl adipate and DGEBA is 2000 and 3200 MPa, respectively. The alpha transition temperature through peak of the loss modulus and the peak of tan(δ), are 77 °C and 90 °C, respectively. Low‐viscosity epoxy applications are discussed herein. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2625–2631     

Synthesis,isolation, characterization,and properties of small-size aromatic macrocycles for poly(arylene ether ketone)s

A series of macrocyclic arylene ether ketone oligomers from 4,4′-difluorobenzophenone, 2,4′-difluorobenzophenone and 1,3-bis(4′-fluorobenzoyl)benzene were prepared via aromatic nucleophilic substitution according to the pseudo-high dilution principle. Small-size aromatic macrocycles were isolated by silica gel column chromatography with cyclohexane/ethyl acetate as eluent. The chemical structures of these small-size macrocycles were characterized by matrix-assisted laser desorption ionization–time-of-flight–mass spectrometry (MALDI–TOF–MS), IR, ¹⁹F-,¹H-, and ¹³C-NMR, and GPC techniques. Molecular chain length and steric hindrance of monomers affected the product compositions. The NMR results show that there are different chemical shifts in the different ring-size macrocyclic poly arylene ether ketones in spite of having the same repeating unit. The crystallizability and thermal properties of small-size arylene ether ketone macrocycles were also investigated by DSC, WAXD, TGA, and the results suggest that the crystallization and thermal properties are related to their intrinsic chemical structures. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1957–1967, 1999