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To achieve high-performance thermosets, three diallyl-containing main-chain type benzoxazine polymers, (MCBP) were prepared from Mannich condensation of 2,2′-diallyl bisphenol A, paraformaldehyde, and three diamines: 4,4′-diaminodiphenylmethane (DDM), 4,4′-oxydianiline (ODA), and 2,2′-bis(4-(4-aminophenoxy)phenyl)propane (BAPP), respectively. These MCBPs can be cured and general a phenolic hydroxyl type benzoxazine thermosets even though no free ortho and free para positions to the oxygen of oxazine in their structures. After thermally curing, the resulting thermosets display much higher T g than the thermosets of 2,2′-diallyl bisphenol A/aniline-based, 2-allyl phenol/DDM-based, and 2-allylphenol/ODA-based benzoxazine, demonstrating the advantage of MCBP on thermal properties over monomer type benzoxazines. The refractive index of the thermosets is higher than 1.689 at 589 nm, which is relatively high compared with other polymers. These results demonstrate the advantage of diallyl-containing MCBPs on thermal properties and refractive index over allyl-containing monomer type benzoxazines. [ABSTRACT FROM AUTHOR]

ABSTRACT We have developed a sequence-dependent synthesis of the amino-functionalized poly(ether sulfone) P2. The amino groups of P2 act as reactive sites toward epoxy resins. After curing P2 with diglycidyl ether of bisphenol A (DGEBA) and cresol novolac epoxy (CNE), we obtained the flexible, light-yellow, transparent, epoxy thermosetting films P2/DGEBA, and P2/CNE, respectively, having glass transition temperatures ( Tg) of 258 and 274°C, respectively. In addition, we also prepared a flexible film after condensation of the amino groups of P2 with the anhydride groups of 4,4′-oxydiphthalic anhydride (ODPA); after imidization at 300°C for 1 h, the resulting P2/ODPA thermosetting film possessed a value of Tg of 340°C. These three thermosetting films also exhibited flame retardancy with a UL-94 VTM-0 grade. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40980. [ABSTRACT FROM AUTHOR]

ABSTRACT A propargyl ether-containing benzoxazine (4) was prepared from a potassium carbonate-catalyzed nucleophilic substitution of propargyl bromide and a phenolic OH-containing benzoxazine (3), which was prepared from 1-(4-hydroxyphenyl)-1-(4-aminophenyl)-1-(6-oxido-6H -dibenz <1,2> oxaphosphorin-6-yl)ethane (1) by a three-step procedure. The curing reactions of (4) were monitored by IR and DSC. A reaction mechanism was proposed based on the observation. Benzoxazines (3) and (4) were applied as epoxy curing agents. The microstructure and the structure-property relationship of the resulting thermosets are discussed. The double-strand structure in (4)-cured epoxy thermosets afforded higher crosslinking density, and led to higher thermal properties. In addition, the (4)-cured epoxy thermosets possess half the amount of highly polar hydroxyl groups than those of the (3)-cured epoxy thermosets, resulting in a lower dielectric constant, dissipation factor, and water absorption. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1359-1367 [ABSTRACT FROM AUTHOR]

We prepared a side-chain phenol-functionalized poly(ether sulfone) (P1) from a one-pot reaction of a 4,4′-dihydroxybenzophenone (DHBP)-based poly(ether sulfone), poly(oxy-1,4-phenylenecarbonyl-1,4-phenyleneoxy-1,4-phenylene-sulfonyl-1,4-phenylene (DHBP-PES)), with 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and phenol in the presence of sulphuric acid. The phenol linkages of P1 act as reacting sites for epoxy resins. Subsequently, flexible and light-yellow transparent films of epoxy thermosets can be achieved from the curing of P1 with cresol novolac epoxy (CNE) and diglycidyl ether of bisphenol A (DGEBA). The thermoset based on P1 and CNE (P1/CNE) shows a high T g value (241 °C), a low coefficient of thermal expansion (44 ppm/°C), and flame retardancy (VTM-0). The moderate-to-high molecular weight of P1 is responsible for the characteristics high T g and flexibility, which are rarely seen in epoxy thermosets based on a low-molecular weight curing agent. [ABSTRACT FROM AUTHOR]

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

A benzoxazine ( P-bapf) based on 9,9-bis(4-aminophenyl)fluorene (BAPF), phenol, and formaldehyde was successfully prepared using two-pot and one-pot procedures. In the two-pot approach, BAPF initially reacted with 2-hydroxybenzaldehyde, leading to 9,9-bis(4-(2-hydroxybenzylideneimino)phenyl)fluorene. The imine linkages of 9,9-bis(4-(2-hydroxybenzylideneimino)phenyl)fluorene were then reduced by sodium borohydride, forming 9,9-bis(4-(2-hydroxybenzylamino)phenyl)fluorene. Finally, paraformaldehyde was added to induce ring closure condensation, forming benzoxazine ( P-bapf). In the one-pot approach, P-bapf was obtained directly by reacting BAPF, phenol, and paraformaldehyde in various solvents. Among the solvents, we found that using toluene/ethanol (2/1, v/v) as a solvent leads to the best purity and yield. No gelation was observed in the preparation. The structure of the resulting benzoxazine was confirmed by 1H, 13C, 1H1H and 1H13C NMR spectra. P-bapf exhibits a photoluminescent emission at 395 nm under an excitation of 275 nm. After curing, the resulting P-bapf thermoset exhibits Tg as high as 236 °C, and the Tg can be further increased to 260 °C by copolymerization with an equal equivalent of cresol novolac epoxy. The 5% degradation temperature of the P-bapf thermoset reaches as high as 413 °C (N2) and 431 °C (air). The refractive index at 589 nm is as high as 1.70, demonstrating a high refractive index characteristic of fluorene linkage. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

Abstract: An aromatic triamine-based flame-retardant benzoxazine (3), which could not be prepared by the traditional approaches, was successfully prepared by a three-step procedure. The first step is the condensation of 2-hydroxybenzaldehyde with an aromatic triamine, forming intermediate (1) with an imine linkage. The second step is the reduction of the imine linkage by sodium borohydride, resulting in intermediate (2) with a secondary amine linkage. The third step is the ring closure condensation of (2), leading to benzoxazine (3). The structures of (1–3) were confirmed by IR, high-resolution mass, 1H and 31P NMR spectra. Benzoxazine (3) was copolymerized with commercial benzoxazines. According to the measurements, thermal properties, flame retardancy, dimensional stability of commercial polybenzoxazines were significantly improved via the incorporation of (3). [Copyright &y& Elsevier]

Two flame‐retardant epoxy curing agents, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐yl‐tris(4‐hydroxyphenyl)methane (1) and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐yl‐ (4‐aminophenyl)‐bis(4‐hydroxyphenyl)methane (2), were prepared by a facile, economic, one‐pot procedure. The structures of the curing agents were confirmed by IR, high‐resolution mass, 1‐D, and 2‐D NMR spectra. A reaction mechanism was proposed for the preparation, and the effect of electron withdrawing/donating effects on the stabilization of the carbocation was discussed. (1‐2) served as curing agents for diglycidyl ether of bisphenol A (DGEBA), dicyclopentadiene epoxy (HP‐7200), and cresol novolac epoxy (CNE). Properties such as glass transition temperature, coefficient of thermal expansion, thermal decomposition temperature, and flame retardancy of the resulting epoxy thermosets were evaluated. The resulting epoxy thermosets show high Tg, low thermal expansion, moderate thermostability, and excellent flame retardancy. The bulky biphenylene phosphinate pendant makes polymer chains difficult to rotate, explaining the high Tg and low thermal expansion characteristic. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7898–7912, 2008 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Three bio-based benzoxazines was successfully prepared from three biphenols, furfurylamine, and paraformaldehyde. • The co-solvent of xylene/pentanol is a successful media to prepare the three benzoxazines. • The properties of the three benzoxazines are strongly related to the number of free ortho to the oxygen of oxazine. • Two of the three benzoxazines show promising properties after thermal curing. (T g > 283 °C) Abstract The purpose of this work is to achieve high-performance benzoxazine thermosets from renewable biomass such as furfurylamine and vanillin-derived biphenol. The benzoxazine (DVP-fu) derived from a vanillin-derived biphenol and furfurylamine shows promising properties after thermal curing. To understand the structure-property relationship, two other structurally-similar benzoxazines (DHP-fu and DVG-fu) derived from biphenols (DHP and DVG) were prepared. Thermal analyses (DMA, TMA, and TGA) show that the thermosets of DHP-fu and DVP-fu are high-performance materials, demonstrating that the sustainability and high performance could be achieved simultaneously. This study found that their properties are strongly related to the number of free ortho to the oxygen of oxazine. [ABSTRACT FROM AUTHOR]