Synthesis and characterization of a novel acetylene‐ and maleimide‐terminated benzoxazine and its high‐performance thermosets

A novel acetylene‐ and maleimide‐terminated benzoxazine, 3‐(3‐ethynylphenyl)‐3,4‐dihydro‐2H‐6‐(N‐maleimido)‐1,3‐benzoxazine (MBZ‐apa), was successfully synthesized with N‐(4‐hydroxyphenyl)maleimide, paraformaldehyde, and 3‐aminophenylacetylene. The structure of the benzoxazine is confirmed by FTIR and ¹H‐NMR spectroscopies. MBZ‐apa is easily dissolved in common organic solvents. Differential scanning calorimetry (DSC) was used to study thermal cross‐linking behavior of MBZ‐apa. The DSC curve shows only a single exothermic peak due to the oxazine ring‐opening polymerization and the polymerization of the acetylene and maleimide groups occurring simultaneously in the same temperature range. Dynamic mechanical analyses (DMA) reveals that the novel polybenzoxazine exhibits high glass‐transition temperature (T_g) (ca. 348°C). The storage modulus arrives at 4.5 GPa in the range of room temperature to 330°C. The polybenzoxazine exhibits good thermal stability as evidenced by thermogravimetric analysis (TGA). Pyrolysis‐gas chromatography/mass spectrometry (Pyrolysis‐GC/MS) was employed to characterize the polybenzoxazine. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of new polybenzoxazines from renewable resources for bio‐composite applications

Renewable natural resources such as eugenol, furfurylamine, stearylamine, and jute fiber were used to prepare polybenzoxazine composites. The purity of eugenol which is extracted from clove was confirmed by gas chromatography. FTIR, ¹H, and ¹³C NMR spectroscopic analysis were used to determine the structure of eugenol and the benzoxazine monomers namely 6‐allyl‐3‐furfuryl‐8‐methoxy‐3,4‐dihydro‐2H‐1,3‐benzoxazine (EF‐Bz) and 6‐allyl‐3‐octadecyl‐8‐methoxy‐3,4 dihydro‐2H‐1,3‐benzoxazine (ES‐Bz) synthesized from it. The curing analysis from differential scanning calorimetric analysis shows that the onset of curing is shifted to lower temperature (161°C) for EF‐Bz, when compared with ES‐Bz (174°C). The thermal stability analyzed from thermogravimetric analysis shows that the polybenzoxazine EF‐Pbz has higher thermal stability (T_5% = 361°C) with that of ES‐Pbz (T_5% = 313°C). The storage modulus, tensile, and flexural strength of the EF‐Bz/Jute fiber composite show high value when compared with ES‐Bz/Jute fiber composites. POLYM. COMPOS., 37:1821–1829, 2016. © 2014 Society of Plastics Engineers     

Synthesis and optical properties of poss‐based oxadiazole nanohybrids with three‐dimensional molecular conjugated structure

A series of oxadiazole‐containing molecular hybrid materials with three‐dimensional structure ( P1–P3 ) was prepared by Heck reaction based on the octavinylsilsesquioxane. All resultant hybrid materials are soluble in common organic solvents and possess good film‐forming property. Their structures and properties were characterized and evaluated by FTIR, ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, MALDI‐TOF, UV–vis, photoluminescence (PL), cyclic voltammetry, and elemental analysis (EA). The results showed that the substituted arm numbers of hybrids ( P2 and P3 ) with pushing electron groups were efficiently controlled. Moreover, the hybrids possessed a steady blue emission and good electron‐injecting property in film. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40246.     

Synthesis and characterization of 4,4′‐diaminodiphenyl methane‐based benzoxazines and their polymers

A series of diamine‐based benzoxazine precursors have been prepared using 4,4′‐diaminodiphenyl methane, formaldehyde, and different phenol derivatives including phenol, p‐cresol, and 2‐naphthol. Their chemical structures were identified by FTIR, ¹H NMR, and elemental analysis. The curing reactions of those precursors were monitored by FTIR and DSC. The obtained materials exhibited higher glass transition temperature and char yields than the corresponding bisphenol‐A based polybenzoxazines. The polybenzoxazine prepared from phenol showed the highest char yields of 65% and thermal stability with 5 and 10% weight‐loss temperatures at 346 and 432°C, respectively. The polybenzoxazine prepared from 2‐naphthol exhibited the highest glass transition temperature at 244°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Thermally activated polymerization behavior of bisphenol‐S/methylamine‐based benzoxazine

A bifunctional benzoxazine monomer, 6,6′‐bis(3‐methyl‐3,4‐dihydro‐2H‐benzo[e] [1,3]oxazinyl) sulfone (BS‐m), was synthesized from bisphenol‐S, methylamine, and formaldehyde via a solution method. The chemical structure of BS‐m was characterized with ¹H and ¹³C‐nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and elemental analysis. The ring‐opening polymerization reaction of BS‐m monomer was studied by FTIR, ¹³C solid‐state NMR, and differential scanning calorimetry. With the polymerization reaction proceeding, the intensities of the FTIR absorption peaks of CH₂, C? O? C, and C? N? C of the oxazine ring decreased gradually, and some of these absorption peaks disappeared. The shapes and intensities of the absorption peaks associated with benzene ring, sulfone group, and aromatic C? S bond changed in various ways. The changes in the solid‐state ¹³C‐NMR pattern, including chemical shifts, intensity of resonances, and line‐width, were observed from the spectra of BS‐m and the corresponding polybenzoxazine. The melting process of BS‐m overlapped with the beginning of the ring‐opening polymerization reaction. The polymerization kinetic parameters were evaluated for nonisothermal and isothermal polymerization of BS‐m. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of UV‐curable acrylic resin containing fluorine groups

A novel fluorine‐containing acrylic resin, 4‐trifluoromethylphenyl glycerol dimethacrylate (TPGD), was synthesized and the structure was characterized by FTIR, ¹³C NMR, ¹H NMR, and ¹⁹F NMR spectroscopy. The conversion of cure reaction, thermal stability, glass transition temperature (T_g), and electrical properties of the TPGD acrylic resin cured with UV radiation were investigated. The thermal stability and T_g of the UV‐cured specimens show a maximum value at 1 wt% photoinitiator, due to the formation of advanced network structures. The cured specimens had a relatively low dielectric constant, attributed to the decreased deformation polarizability of segment motion in the fluorine‐containing resin. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of 2‐oxazoline‐benzoxazine compound and its polymer

A novel 2‐oxazoline‐benzoxazine (POB) was synthesized with 2‐(hydroxylphenyl)‐2‐oxazoline, 1,3,5‐triphenylhexahydro‐1,3,5‐triazine and paraformaldehyde. The chemical structure of the monomer was confirmed by FTIR, ¹H‐NMR, ¹³C‐NMR, and MS. The curing behavior of the monomer was studied by DSC and FTIR, and the ring opening reaction of the monomer was found to occur from 187.5°C. The results of DMA and TGA demonstrated that the thermal properties of polymer for POB monomer (P‐m) are better than polymer for POB precursor (P‐p), because that the oligomer in benzoxazine precursor decreased the perfection of the polymer's network structure; it was also found that the thermal properties of P‐m and P‐p are much better than the common polybenzoxazine and the composite material of benzoxazine and 2‐oxazoline. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci , 2008.     

Synthesis and characterization of acetylene‐terminated polybenzoxazines based on polyaralkyl‐phenolic prepolymer

Xylok polybenzoxazine with acetylene group terminals (XPBZAs) were synthesized by the Mannich‐like condensation of Xylok prepolymer, formaldehyde, aminophenylacetylene, and aniline, and their structures were characterized by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (¹H NMR). The curing behavior of XPBZAs was determined by differential scanning calorimetry and FTIR. Thermal behavior and dynamic mechanical properties of the cured XPBZAs were investigated using thermogravimetric analysis and dynamic mechanical analysis. The results showed glass transition temperature (T_g), the thermal stability, and anaerobic char residue of cured XPBZAs increased as the content of acetylene groups increased. POLYM. ENG. SCI., 50:1751–1757, 2010. © 2010 Society of Plastics Engineers     

Preparation of polysiloxane oligomers bearing benzoxazine side groups and tunable properties of their thermosets

A new pathway for the preparation of polysiloxane oligomers bearing benzoxazine side groups were reported via the hydrolysis and co‐polycondensation of benzoxazinyl siloxane (SBZ) with dimethyldiethoxysilane (DEDMS). The structures of SBZ and oligomers were characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The average molecular weights of the obtained oligomers were estimated from size exclusion chromatography and ¹H‐NMR to be in the range of 2000–4000. The oligomers gave transparent films by casting in THF solution. The films were further thermally treated to produce crosslinked films via the ring opening polymerization of benzoxazine side group. The effects of siloxane content on polymerization behavior, glass transition temperature, and mechanical properties of the polybenzoxazine thermosets were investigated. Tensile test of the films revealed that the elongation at break increased with increasing siloxane content. The elongation at break of poly(I‐50) was up to 12.1%. Dynamic mechanical analysis of the thermosets showed that the T_gs were in the range of 119–165°C. Thermogravimetic analysis also revealed a better thermal stability as evidenced by the 5% weight loss temperatures in the range of 363–390°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40960.     

Studies on the structure of activated carbon fibers activated by phosphoric acid

By solid‐state ¹³C‐ and ³¹P‐NMR, XPS, and FTIR, the chemical structure of activated carbon fiber–P (ACF‐P) and its reaction with phosphoric acid were studied. Even when activated at low temperatures, these fibers developed a graphitelike carbon structure with a certain amount of phenol groups as well as acetal (or methylenedioxy) carbon. As expected, the oxygen‐containing groups were greatly reduced at high activation temperatures. Different from the ACF‐W, metaphosphoric acid (or polyphosphates) and a small amount of phosphorus exist on ACF‐P. The original ACF‐P activated at low temperature contained a lot of phosphoric acid, so it had to be washed with water to expose the large surface area. The washing process can be omitted for ACF‐P activated at high temperature because most phosphorus compounds in fiber have volatilized. The ACF‐P activated at lower temperature possessed a large amount of oxygen‐containing surface groups and had enhanced adsorption ability for polar adsorbates. The remaining of metaphosphoric acid enhanced the adsorption of silver ion. The experimental results showed that the peaks of ³¹P‐NMR, P_2p‐XPS, and FTIR at 1620 cm^?1 shifted with the increase of activated temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2253–2261, 2003     

Synthesis,polymerization, and properties of the allyl‐functional phthalonitrile

A novel bisphthalonitrile monomer containing allyl groups (DBPA‐Ph) had been synthesized via the reaction of diallyl bisphenol A (DBPA) and 4‐nitrophthalonitrile. The chemical structure of DBPA‐Ph was confirmed by ¹HNMR, ¹³CNMR, and FTIR spectroscopy. The curing behaviors and processability of DBPA‐Ph were studied by differential scanning calorimetry (DSC) and dynamic rheological analysis. The monomer manifested a two‐stage thermal polymerization pattern. The first stage was attributed to the polymerization of allyl groups and the second to the ring‐form polymerization of cyano groups. The result of dynamic rheological analysis indicated the monomer had wide curing window and the self‐catalyzed curing behavior. DBPA‐Ph polymers were prepared from the thermal polymerization with short curing time, showing high glass transition temperature (>350°C) and attractive thermal decomposition temperature (>430°C). The outstanding glass transition temperature, desirable thermo‐oxidative stabilities, good processability and sound process conditions could provide more applications to the DBPA‐Ph polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41203.     

Synthesis and characterization of a novel functional monomer containing cyano and propenylphenoxy groups and the properties of its copolymer with bismaleimide (BMI)

A novel functional monomer containing cyano and propenylphenoxy groups, 2,6‐di{2‐[(E)‐l‐propenyl]phenoxy}benzonitrile (DPPB) was prepared with high stereospecificity by the reaction of 2,6‐dichlorobenzonitrile and 2‐allylphenol in a mixed solvent system of N‐methylpyrrolidone (NMP)/toluene in the presence of anhydrous potassium carbonate. The chemical structure of the product was characterized by FTIR, ¹H NMR and ¹³C NMR. The monomer was then used to modify a popular commercial bismaleimide, 4,4‐bismaleimidodiphenylmethane (BMDPM), for improving the shear strength of the resin. The results showed that the modified resin could attain 4.7 times the shear strength of neat BMDPM and good heat resistance when the composition of DPPB in the modified resin was 45% (by weight). © 2002 Society of Chemical Industry     

Synthesis and characterization of polyhydroxylated polybutadiene binding 2,2′‐thiobis(4‐methyl‐6‐tert‐butylphenol) with isophorone diisocyanate

A macromolecular hindered phenol antioxidant, polyhydroxylated polybutadiene containing thioether binding 2,2′‐thiobis(4‐methyl‐6‐tert‐butylphenol) (PHPBT‐b‐TPH), was synthesized via a two‐step nucleophilic addition reaction using isophorone diisocyanate (IPDI) as linkage. First, the ? OH groups of PHPBT reacted with secondary ? NCO groups of IPDI to form the adduct PHPBT‐NCO, then the PHPBT‐b‐TPH was obtained by one phenolic ? OH of 2,2′‐thiobis(4‐methyl‐6‐tert‐butylphenol) (TPH) reacting with the PHPBT‐NCO. The PHPBT‐b‐TPH was characterized by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance (¹H‐NMR), ¹³C‐NMR, and thermogravimetric analysis, and its antioxidant activity in natural rubber was studied by an accelerated aging test. Influences of reaction conditions on the two nucleophilic reactions between ? OH group and ? NCO group were investigated. In addition, catalytic mechanism for the reaction between PHPBT‐NCO and TPH was discussed. The results showed that the adduct PHPBT‐NCO could be obtained by using dibutyltin dilaurate (DBTDL) as catalyst, and the suitable temperature and DBTDL amount were 35°C and 3 wt %, respectively. However, triethylamine (TEA) was more efficient than DBTDL to catalyze the reaction between PHPBT‐NCO and TPH because of steric hindrance effect. In addition, it was found that the thermal stability and antioxidant activity of PHPBT‐b‐TPH were higher than those of the low molecular weight antioxidant TPH. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40942.     

Synthesis and nonlinear optical properties of novel y‐type polyurethanes containing different concentrations of chromophore

A new series of Y‐type polyurethanes containing different concentrations of nonlinear optical (NLO) chromophore with aniline donor and tricyanofurane (TCF) acceptor have been successfully prepared, and characterized by FTIR, UV‐Vis, and ¹H‐NMR spectra. New polyurethanes were synthesized with different chromophore contents by introducing diol N, N‐dihydroxyethylaniline or 4‐[N, N‐(dihydroxyethyl)amino]benzaldehyde. These NLO polyurethanes exhibit good film forming property and high thermal stability up to 281°C. The highest electro‐optic coefficient (r₃₃) of polymers is up to 39 pm V^?1 measured by simple reflection technique at 1310 nm, and the temporal stability of the poling‐induced order at elevated temperature of 80°C was much improved through the introducing of hydrogen bonding interaction in this system. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and Characterization of Estolide Esters Containing Epoxy and Cyclic Carbonate Groups

The unsaturated sites in oleic 2‐ethylhexyl estolide esters (containing 35 % monoenic fatty acids) were converted into epoxide and five‐membered cyclic carbonate groups and the products characterized by Fourier transform infrared spectra (FTIR), ¹H, and ¹³C nuclear magnetic resonance (NMR) spectroscopies. Epoxidation of the alkene bonds was accomplished using performic acid generated in situ from formic acid and hydrogen peroxide. Greater than 90 % alkenes were converted into their corresponding epoxide groups as determined by oxirane values and the epoxide ring structure was confirmed by ¹H and ¹³C NMR. The estolide ester epoxide material was subsequently reacted with supercritical carbon dioxide in the presence of tetrabutylammonium bromide catalyst to produce the corresponding estolide ester containing the cyclic carbonate group. The signals at 1,807 cm^?1 and δ 82 ppm in the FTIR and ¹³C‐NMR spectra, respectively, confirmed the desired cyclic carbonate was produced. The carbonated estolide ester exhibited a dynamic viscosity, at 25 °C, of 172 mPa·s as compared to 155 mPa·s for the estolide ester starting material. The estolide ester structure of these new derivatives was shown to be consistent throughout their synthesis.     

Poly(vinyl pyrrolidone‐co‐octavinyl polyhedral oligomeric silsesquioxane) hybrid nanocomposites: Preparation,thermal properties,and Tg improvement mechanism

A series of poly(vinyl pyrrolidone‐co‐octavinyl polyhedral oligomeric silsesquioxanes) (PVP‐POSS) organic–inorganic hybrid nanocomposites containing different percentages of POSS were prepared via free radical polymerization and characterized by FTIR, high‐resolution ¹H‐NMR, solid‐state ²⁹Si‐NMR, GPC, DSC, and TGA. POSS contents in these nanocomposites can be effectively controlled by varying the POSS feed ratios which can be accurately quantified by FTIR curve calibration. On the basis of ²⁹Si‐NMR spectra, average numbers of reacted vinyl groups of each octavinyl‐POSS macromer are calculated to be 5–7, which depends on POSS feed ratios. Both GPC and DSC results indicate that these nanocomposites display network structure and the degree of crosslinking increases with the increase of the POSS content. The incorporation of POSS into PVP significantly improves their thermal properties (T_g and T_dec) primarily due to crosslinking structure and dipole–dipole interaction between POSS cores and PVP carbonyl groups. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Curing characteristics,kinetics, and thermal properties of multifunctional fluorene benzoxazines containing hydroxyl groups

In this article, 9, 9-bis (4-aminophenyl)-2, 7-dihydroxy-fluorene (BADHF) was synthesized using methylsulfonic acid as catalyzer by direct condensation. Two kinds of novel multifunctional benzoxazine monomers containing fluorenyl groups and hydroxyl groups (MB-FH) were obtained from the chemical reaction of BADHF, salicylaldehyde, paraformaldehyde, and ethanolamine (or diethyleneglycolamine) through the adoption of o-hydroxy-benzylamine method and one-step Mannich condensation reaction method. In the traditional three-step synthesis method, the double bond reduction process took 8–12 h, but in this article, it only took 15 min. The structures of MB-FH monomers and their intermediates were characterized by Fourier transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance (¹H NMR). The curing behaviors, curing kinetics, and thermal properties of MB-FH monomers were tested by using a dynamic rheometer, differential scanning calorimeter (DSC), FTIR, dynamic mechanical analysis (DMA), and thermogravimetric analyzer (TGA). The curing induction time can be apparently shortened by the introduction of hydroxyl groups into benzoxazine monomers, and it can catalyze the ring-opening polymerization of oxazine rings at lower temperatures, and improve the interaction of hydrogen bonds in the structure of polybenzoxazine.     

Synthesis and characterization of novel pH‐responsive poly(2‐hydroxylethyl methacrylate‐co‐N‐allylsuccinamic acid) hydrogels for drug delivery

In this study, N‐allylsuccinamic acid (NASA) was synthesized in a single step with a yield of 85%. Carboxylic acid containing NASA was characterized through Fourier transform infrared (FTIR) radiation and ¹H‐NMR and ¹³C‐NMR analysis, and then it was used for synthesis of poly(2‐hydroxylethyl methacrylate‐co‐N‐allylsuccinamic acid) [p(HEMA‐co‐NASA)] hydrogels. The structure of the obtained pH‐responsive p(HEMA‐co‐NASA) hydrogels were characterized with FTIR spectroscopy and scanning electron microscopy analysis, and their swelling characterization was carried out under different drug‐release conditions. In the application step of the study, the hydrogels were used for the in vitro release of vitamin B12 and Rhodamine 6G, which were selected as model drugs. We determined that the hydrogels used as a drug‐delivery matrix could release the drug they had absorbed under different release conditions (phosphate‐buffered saline, 0.9% NaCl, and pH 1.2) at high rates for time periods of up to 24 h. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39660.     

Synthesis and characterization of poly(methacrylates) containing spiroacetal and norbornene moieties in side chain

A four‐step synthetic strategy was applied to achieve novel methacrylic monomers. 5‐Norbornene‐2,2‐dimethanol was prepared from a Diels–Alder reaction of cyclopentadiene and acrolein, followed by the treatment of the adduct with an HCHO/KOH/MeOH solution. The resulting 1,3‐diol (1) was then acetalized with different aromatic aldehydes having OH groups on the ring to produce four spiroacetal derivatives. The reaction of methacryloyl chloride with the phenolic derivatives led to four new methacrylic monomers that were identified spectrochemically (mass, FTIR, ¹H‐NMR, and ¹³C‐NMR spectroscopy). Free radical solution polymerization was used to prepare novel spiroacetal–norbornene containing polymethacrylates, which were characterized by FTIR and ¹H‐NMR spectroscopy and differential scanning calorimetry and thermogravimetric thermal analysis. Gel permeation chromatography was performed to determine molecular weight averages and polydispersity. The polymethacrylate having naphthalenic nuclei was recognized to be the highest molecular weight polymer (M̄_n = 12144, η_inh = 0.80 dL/g) with the highest thermal stability. All the polymers showed good solubility in a variety of common organic solvents. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 30–38, 2000     

Synthesis of a novel benzoxazine‐containing benzoxazole structure and its high performance thermoset

A novel benzoxazine containing benzoxazole structures (Boz‐BOA) was synthesized and its thermoset [P(Boz‐BOA)] was prepared. For comparison, another benzoxazine‐based 4,4′‐diamine diphenyl methane (Boz‐MDA) was also synthesized using a simplified procedure. The structure of Boz‐BOA and Boz‐MDA was confirmed by Fourier transform infrared (FTIR) and ¹H‐NMR. Using FTIR and differential scanning calorimetric scans method, the curing behavior of Boz‐BOA was probed, and the structure of P(Boz‐BOA) was addressed, which was similar to that of P(Boz‐MDA). Data of dynamic mechanical analysis showed that P(Boz‐BOA) exhibited a better modulus retention at high temperature than P(Boz‐MDA), which was attributed to benzoxazole structure restricting the mobility of chains, even at high temperature. P(Boz‐BOA) also exhibited high glass transition temperature (T_g), excellent thermal stability, and low coefficient of thermal expansion value at wide temperature range. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012