Novel heterocyclic poly(arylene ether ketone)s: Synthesis and polymerization of 4‐(4′‐hydroxyaryl)(2H)phthalazin‐1‐ones with methyl groups

Based on green chemistry, a simple and efficient direct synthesis of 4‐(4′‐hydroxyaryl)(2H)phthalazin‐1‐ones ( 2a–2f ) was developed in a two‐step reaction, in which the Friedel–Crafts acylation reaction of six phenols with phthalic anhydride was initially carried out and then followed by cyclization with hydrazine hydrate in good to excellent yields with high regioselectivity. A number of novel heterocyclic poly(arylene ether ketone)s were prepared conveniently from several unsymmetrical, twist, and noncoplanar phthalazinone‐containing monomers ( 2a–2f ) and an activated difluoro monomer via a N? C coupling reaction. It was very interesting that the obtained monomers and polymers exhibited diverse properties with the variation of the number and location of the substituted methyl groups. All these polymers had a high molecular weight with M_n and η_inh in the range of 44,960–169,000 Da and 0.38–0.79 dL/g, respectively. Actually, the obtained polymers displayed excellent thermal properties with T_g's ranging from 222 to 248 °C and 5% weight loss temperatures in nitrogen higher than 430 °C. Moreover, these polymers were readily soluble in common organic solvents, such as N‐methyl‐2‐pyrrolidone, chloroform, pyridine, and m‐cresol, and could be cast into flexible and colorless or nearly colorless films by spin‐coating or casting processes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1525–1535, 2007     

Synthesis of highly refractive and transparent polyimides derived from 4,4′‐thiobis[2″,6″‐dimethyl‐4″‐(p‐phenylenesulfanyl)aniline]

New sulfur‐containing aromatic diamines with methyl groups at the ortho position of amino groups have been developed to prepare highly refractive and transparent aromatic polyimides (PIs) in the visible region. All aromatic PIs derived from 4,4′‐thiobis[2″‐methyl‐4″‐(p‐phenylenesulfanyl)aniline ( 2 ), 4,4′‐thiobis[2,″6″‐dimethyl‐4″‐(p‐phenylenesulfanyl)aniline ( 5 ), and aromatic dianhydride, 4,4′‐[p‐thiobis(phenylenesulfanyl)]diphthalic anhydride ( 6 ) were prepared via a two‐step polycondensation. All PIs showed good thermal properties, such as 10% weight loss temperature in the range of 497–500 °C and glass transition temperatures above 196 °C. In addition, the PIs showed good optical properties, such as optical transparency above 75% at 450 nm with a 10‐μm film thickness, high refractive indices ranging from 1.7135 to 1.7301, and small in‐plane/out‐of‐plane birefringences between 0.0066 and 0.0076. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 656–662, 2010     

Synthesis and properties of fluorene‐based polyheteroarylenes for photovoltaic devices

Novel copolymers consisting of the alternating push–pull comonomers fluorene and thieno[3,4‐b]pyrazine/quinoxaline were synthesized by a palladium‐catalyzed Suzuki cross‐coupling reaction in 60–80% yields. The structure of the deeply colored copolymers was confirmed with ¹H and ¹³C NMR. All the new materials were characterized with spectroscopic and electrochemical methods. Bulk heterojunction organic solar cells based on some of the novel polymers in combination with the well‐known fullerene acceptor [6,6]‐phenyl C₆₁–butyric acid methyl ester were fabricated, and their photovoltaic parameters were measured. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6952–6961, 2006     

Energetic polymer salts from 1‐vinyl‐1,2,4‐triazole derivatives

Energetic polymers salts from 1‐vinyl‐1,2,4‐triazole derivatives have been synthesized via free radical polymerization of 1‐vinyl‐1,2,4‐triazolium monomer salts or by protonation of poly(1‐vinyl‐1,2,4‐triazole) with inorganic or organic acids. Standard enthalpies of formation of the new monomer salts were calculated using the computationally feasible DFT(B3LYP) and MP2 methods in conjunction with an empirical approach based on densities of salts. Compared with the monomer salts, the polymer salts have good thermal properties with high densities > 1.5 g cm^?3. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2414–2421, 2008     

Synthesis and properties of π‐conjugated dithiafulvene oligomers by addition of a monofunctionalized compound

Dithiafulvene oligomers ( 3 ) were prepared by cycloaddition polymerization of aldothioketenes with their alkynethiol tautomers derived from 1,4‐diethynylbenzene ( 2 ) with the addition of 1‐ethynyl‐4‐methylbenzene ( 1 ) as a monofunctionalized compound. Different feed ratios of 2 / 1 were used to control the molecular weights of 3 . The structures of 3 were confirmed by IR and ¹H NMR spectroscopies in comparison with those of 2‐(4‐tolylidene)‐4‐tolyl‐1,3‐dithiol ( 4 ) as a model compound, which was obtained by the treatment of lithium 2‐tolylethynethiolate with water in Et₂O. The number‐average degree of polymerization (DP) and the number‐average molecular weight were measured by gel permeation chromatographic and ¹H NMR analysis. DP increased with an increasing feed ratio of 2 / 1 . The ultraviolet–visible spectra of 3 in diluted acetonitrile showed that the absorption maxima of 3 increased with an increasing DP of 3 . These redshifts are ascribed to an effective expansion of the π‐conjugation system in 3 . The oligomers exhibited a maximum conjugation length of seven repeating units. The redox properties of 3 were examined by cyclic voltammetry. The oxidation half‐peak potentials (E_p/2) of 3 were slightly cathodically shifted with increasing DP. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 708–715, 2003     

Synthesis and properties of fluorine‐containing poly(aryl ether oxadiazole)s

Fluorine‐containing poly(aryl ether 1,3,4‐ozadiazole)s were synthesized by the nucleophilic aromatic substitution reaction of 2,5‐bis(2,3,4,5,6‐pentafluorophenyl)‐1,3,4‐oxadiazole and various bisphenols in the presence of potassium carbonate. The polymerizations were carried out at 30 °C in 1‐methyl‐2‐pyrrolidinone to avoid the gelation caused by a crosslinking reaction at para and ortho carbons to the 1,3,4‐oxidiazole ring. The obtained polymers were all para‐connected linear structures. The obtained fluorine‐containing poly(aryl ether 1,3,4‐ozadiazole)s showed excellent solubility and afforded tough, transparent films by the solution‐casting method. They also exhibited a high glass transition temperature depending on the molecular structure, and the glass transition temperature could be controlled by the bisphenols in the range of 157–257 °C. They showed good thermal stability and excellent hydrophobicity due to the incorporation of the 2,3,5,6‐tetrafluoro‐1,4‐phenylene moiety. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2855–2866, 2007     

Near‐infrared electrochromic poly(aryl ether)s based on isolated electroactive tetraphenyl‐p‐phenylenediamine moieties

A series of near‐infrared (NIR) electrochromic aromatic poly(aryl ether)s containing N,N,N′,N′‐tetraphenyl‐p‐phenylenediamine (TPPA) moieties in the backbone were prepared from the high‐temperature polycondensation reactions of a biphenol monomer, 2,5‐bis(diphenylamino)hydroquinone, with difluoro compounds. The obtained polymers were readily soluble in many organic solvents and showed useful levels of thermal stability associated with high glass‐transition temperatures (182–205 °C) and high char yields (higher than 40% at 800 °C in nitrogen). The polymer films showed reversible electrochemical oxidation with high contrast ratio both in the visible range and NIR region, and also exhibited high coloration efficiency (CE), low switching time, and stability for electrochromic operation. The polyether TPPA‐a thin film revealed good CE in visible (CE = 217 cm²/C) and NIR (CE = 192 cm²/C) region with reversible electroactive stability (over 500 times within 5% loss relative to its initial injected charge). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5378–5385, 2009     

Synthesis and characterization of soluble polyimides derived from 2′,5′‐bis(3,4‐dicarboxyphenoxy)‐p‐terphenyl dianhydride

A novel bis(ether anhydride) monomer, 2′,5′‐bis(3,4‐dicarboxyphenoxy)‐p‐terphenyl dianhydride, was synthesized from the nitro displacement of 4‐nitrophthalonitrile by the phenoxide ion of 2′,5′‐dihydroxy‐p‐terphenyl, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and cyclodehydration of the resulting bis(ether diacid). A series of new poly(ether imide)s bearing laterally attached p‐terphenyl groups were prepared from the bis(ether anhydride) with various aromatic diamines via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s followed by thermal or chemical imidization to the poly(ether imide)s. The inherent viscosities of the poly(amic acid) precursors were in the range of 0.62–1.26 dL/g. Most of the poly(ether imide)s obtained from both routes were soluble in polar organic solvents, such as N,N‐dimethylacetamide. All the poly(ether imide)s could afford transparent, flexible, and strong films with high tensile strengths. The glass‐transition temperatures of these poly(ether imide)s were recorded as between 214 and 276 °C by DSC. The softening temperatures of all the poly(ether imide) films stayed in the 207–265 °C range according to thermomechanical analysis. For all the polymers significant decomposition did not occur below 500 °C in nitrogen or air atmosphere. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1008–1017, 2004     

Heterocyclic monomers via reissert chemistry

An AA bisphenolic monomer ( 13 ), an AB activated fluoro‐phenolic monomer ( 14 ), and an AB₂ alcohol‐diester monomer precursor ( 17 ), all based on the isoquinoline nucleus, were prepared using Reissert compound chemistry. Additionally, model reactions established the efficiency of condensation of isoquinoline Reissert compounds with dihaloalkanes, providing evidence of the potential of this reaction to produce high molecular weight polymers, which was subsequently realized. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Poly(arylene thioether)s containing 9,9′‐spirobifluorene moieties in the main chain: Masked dithiol‐based synthesis and excellent optical properties

Poly(arylene thioether)s ( PTEs ) containing 9,9′‐spirobifluorene moieties were synthesized in high yields from 9,9′‐spirobifluorene‐2,2′‐bis(N,N‐dimethylcarbamothioate) 4 as the masked dithiol and various difluoroarenes as electrophilic monomers. All PTEs showed high thermal stability: The 10% weight loss temperature as evaluated by thermogravimetric analysis was over 470 °C under both nitrogen and air atmospheres. The glass transition temperature estimated by DSC was in the range 210–270 °C. The PTEs showed high solubility in ordinary organic solvents, such as CHCl₃, NMP, and THF. Most PTEs exhibited remarkably high refractive indices ranging from 1.69 to 1.73 at 587.6 nm, whereas no or little birefringence was observed for the PTEs . © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4192–4199, 2010     

Synthesis of heterocyclic monomers via Reissert chemistry

The chemistry of Reissert compounds has been used to synthesize activated difluorotetraketone monomers containing two coupled isoquinolyl moieties, linked at either the 1,1′‐ or 4,4′‐positions. These monomers offer routes to novel families of poly(heteroarylene ether)s. New 4,4′‐coupled bis(Reissert compound) 9 containing 4,4′‐diketo moieties failed to afford the desired difluorotetraketo monomer upon attempted rearrangement. However, analogous bis(Reissert compound) 19 containing 4,4′‐dibenzyl units did so, via aldehyde condensation, hydrolysis of the intermediate ester and oxidation of the four benzylic moieties to keto groups; thus the novel difluorotetraketone monomer 10 was prepared. Novel bis(Reissert compound)s 24 , 28 , and 35 were synthesized from diacid chlorides and 4‐(p‐fluorobenzyl)isoquinoline. Rearrangement of 24 to the diketone 29 , followed by oxidation of the 4‐benzyl moieties resulted in difluorotetraketone monomer 30 containing a 1,1′‐linked bisisoquinoline. The 1,1′‐linked bis(isoquinolylfluorodiketo) monomer 38 , isomeric with 10 , was prepared from 4‐(p‐fluorobenzyl) Reissert compound 36 by condensation with terephthaldehyde, ester hydrolysis to diol 37 , and oxidation. In the course of this effort, a number of new isoquinoline Reissert compounds were synthesized as model systems. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3856–3867, 2010     

Synthesis,photoluminescence, and electrochromism of novel aromatic poly(amine‐1,3,4‐oxadiazole)s bearing anthrylamine chromophores

Two novel poly(amine‐hydrazide)s were prepared from the polycondensation reactions of the dicarboxylic acid, 9‐[N,N‐di(4‐carboxyphenyl)amino]anthracene ( 1 ), with terephthalic dihydrazide ( TPH ) and isophthalic dihydrazide ( IPH ) via the Yamazaki phosphorylation reaction, respectively. The poly(amine‐hydrazide)s were readily soluble in many common organic solvents and could be solution cast into transparent films. Differential scanning calorimetry (DSC) indicated that these hydrazide polymers had glass‐transition temperatures (T_g) in the range of 182–230 °C and could be thermally cyclodehydrated into the corresponding oxadiazole polymers in the range of 300–400 °C. The resulting poly(amine‐1,3,4‐oxadiazole)s had useful levels of thermal stability associated with high T_g (263–318 °C), 10% weight‐loss temperatures in excess of 500 °C, and char yield at 800 °C in nitrogen higher than 55%. These organo‐soluble anthrylamine‐based poly(amine‐hydrazide)s and poly (amine‐1,3,4‐oxadiazole)s exhibited maximum UV‐vis absorption at 346–349 and 379–388 nm in N‐methyl‐2‐pyrrolidone (NMP) solution, respectively. Their photoluminescence spectra in NMP solution showed maximum bands around 490–497 nm in the green region. The poly(amine‐hydrazide) I ‐ IPH showed a green photoluminescence at 490 nm with PL quantum yield of 29.9% and 17.0% in NMP solution and film state, respectively. The anthrylamine‐based poly(amine‐1,3,4‐oxadiazole)s revealed a electrochromic characteristics with changing color from the pale yellow neutral form to the red reduced form when scanning potentials negatively from 0.00 to ?2.20 V. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1584–1594, 2009     

New ladder‐type conjugated polymer with broad absorption,high thermal stability,and low band gap

New ladder‐type π‐conjugated polymer poly{6‐alkyl‐pyrrolo[3,2‐b:4,5‐b′]bis‐[1,4]benzothiazine} ( PPBBTZ ) was synthesized through a simple method. PPBBTZ showed good solubility in organic solvents (such as chloroform, tetrahydrofuran, chlorobenzene, o‐dichlorobenzene) and high thermal stability (decomposition temperatures up to 323 °C and 299 °C in nitrogen and air, respectively). The highest occupied molecular orbital and lowest unoccupied molecular orbital energy level estimated from electrochemistry result and absorption spectrum were ?5.46 and ?3.81 eV, respectively, with a band gap of 1.65 eV. More interestingly, PPBBTZ displayed broad absorption from ultraviolet to visible light regions (200–750 nm). These properties suggested PPBBTZ was a good candidate in opto‐electronics. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation,characterization, and properties of fluorene‐containing benzoxazine and its corresponding cross‐linked polymer

A benzoxazine compound (FDP‐FBz), which possesses a fluorene group and two terminal furan groups, and its corresponding cross‐linked polymer (CR‐FDP‐FBz) have been prepared using 4,4′‐(9‐fluorenylidene)diphenol (FDP), furfurylamine, and formaldehyde as precursors. The chemical structure of FDP‐FBz has been characterized with Fourier‐transform infrared and ¹H nuclear magnetic resonance spectroscopies. FDP‐FBz displays a melting point at about 173 °C and a processing window of 52 °C as well as good solubility in common organic solvents. As a result, FDP‐FBz can be fabricated in both molten and solution processes. Under an excitation at 365 nm, FDP‐FBz exhibits a photoluminescent (PL) emission at about 445 nm. The PL intensity of FDP‐FBz is as high as sixfolds of the intensity recorded with FDP. CR‐FDP‐FBz displays a glass transition temperature of 215 °C, a high storage modulus of 3.1 GPa, a 10% weight loss at 384 °C, and a high char yield of 56 wt % (900 °C, in nitrogen). Moreover, CR‐FDP‐FBz has a high refractive index of about 1.65 as a result of incorporating fluorene groups to its structure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4020–4026, 2010     

Synthesis and characterization of highly conjugated side‐group‐substituted benzo[1,2‐b:4,5‐b′]dithiophene‐based copolymer for use in organic solar cells

A new donor–acceptor (D–A) conjugated copolymer based on benzo[1,2‐b:4,5‐b′]dithiophene (BDT) and thieno[3,4‐c]pyrrole‐4,6‐dione (TPD) was synthesized via a Stille cross‐coupling reaction. A highly conjugated thiophene‐based side group, tris(thienylenevinylene) (TTV), was incorporated into each BDT unit to generate the two‐dimensional D–A copolymer (PBDT‐TTV). An alkoxy‐substituted BDT‐based TPD copolymer (PBDT‐OR) was synthesized using the same polymerization method for comparison. PBDT‐TTV thin films produced two distinct absorption peaks. The shorter wavelength absorption (458 nm) was attributed to the BDT units containing the TTV group, and the longer wavelength band (567–616 nm) was attributed to intramolecular charge transfer between the BDT donor and the TPD acceptor. The highest occupied molecular orbital energy levels of PBDT‐OR and PBDT‐TTV were calculated to be −5.53 and −5.61 eV, respectively. PBDT‐TTV thin films harvested a broad solar spectrum covering the range 300–700 nm. A comparison with the PBDT‐OR films revealed stronger interchain π–π interactions in the PBDT‐TTV films and, thus, a higher hole mobility. A polymer solar cell device prepared using PBDT‐TTV as the active layer was found to exhibit a higher power conversion efficiency than a device prepared using PBDT‐OR under AM 1.5 G (100 mW/cm²) conditions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 653–660     

Synthesis and photovoltaic properties of 2,6‐bis(2‐thienyl) benzobisazole and 4,8‐bis(thienyl)‐benzo[1,2‐B:4,5‐B′]dithiophene copolymers

In an effort to design efficient low‐cost polymers for use in organic photovoltaic cells the easily prepared donor–acceptor–donor triad of a either cis‐benzobisoxazole, trans‐benzobisoxazole or trans‐benzobisthiazole flanked by two thiophene rings was combined with the electron‐rich 4,8‐bis(5‐(2‐ethylhexyl)‐thien‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene. The electrochemical, optical, morphological, charge transport, and photovoltaic properties of the resulting terpolymers were investigated. Although the polymers differed in the arrangement and/or nature of the chalcogens, they all had similar highest occupied molecular orbital energy levels (?5.2 to ?5.3 eV) and optical band gaps (2.1–2.2 eV). However, the lowest unoccupied molecular orbital energy levels ranged from ?3.1 to ?3.5 eV. When the polymers were used as electron donors in bulk heterojunction photovoltaic devices with PC₇₁BM ([6,6]‐phenyl C₇₁‐butyric acid methyl ester) as the acceptor, the trans‐benzobisoxazole polymer had the best performance with a power conversion efficiency of 2.8%. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 316–324     

9,9′‐spirobifluorene‐containing polycarbonates: Transparent polymers with high refractive index and low birefringence

Syntheses of 2,2′‐bisalcoholic group‐substituted 9,9′‐spirobifluorene monomers 2 were performed by the reaction of 2,2′‐dihydroxy‐9,9′‐spirobifluorene 2a with haloalcohols. Polycarbonates consisting of 9,9′‐spirobifluorene skeleton in the main chain (PC 4 ) were synthesized by the polycondensation of 2,2′‐bisalcoholic monomers 2 and triphosgene or diphenyl carbonate. PC 4 showed good thermal stability: the 5% weight loss temperature was over 330 °C under both nitrogen and air atmospheres. The glass transition temperature was in a range of 16–269 °C estimated by differential scanning calorimetry, depending on the flexibility of the alkylene or oxyethylene chains of 2 . PC 4 showed high solubility toward ordinary organic solvents such as CHCl₃, benzene, and THF, making possible the preparation of the flexible thin films. Very high refractive index in a range of 1.62–1.66 at 589 nm was observed although PC 4 consists only of C, H, and O atoms, whereas very low degree of birefringence was confirmed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3658–3667, 2010     

A vinylene‐linked benzo[1,2‐b:4,5‐b']dithiophene‐2,1,3‐benzothiadiazole low‐bandgap polymer

A new heteroarylene‐vinylene donor–acceptor polymer P(BDT‐V‐BTD) with reduced bandgap has been synthesized and its photophysical, electronic and photovoltaic properties investigated both experimentally and theoretically. The structure of the polymer comprises an unprecedented combination of a strong donor (4,8‐dialkoxy‐benzo[1,2‐b:4,5‐b']dithiophene, BDT), a strong acceptor (2,1,3‐benzothiadiazole, BTD) and a vinylene spacer. The new polymer was obtained by a metal‐catalyzed cross‐coupling Stille reaction and fully characterized by NMR, UV–vis absorption, GPC, TGA, DSC and electrochemistry. Detailed ab initio computations with solvation effects have been performed for the monomer and model oligomers. The electrochemical investigation has ascertained the ambipolar character of the polymer and energetic values of HOMO, LUMO and bandgap matching materials‐design rules for optimized organic photovoltaic devices. The HOMO and LUMO energies are consistently lower than those of previous heteroarylene‐vinylene polymer while the introduction of the vinylene spacer afforded lower bandgaps compared to the analogous system P(BDT‐BTD) with no spacer between the aromatic rings. These superior properties should allow for enhanced photovoltages and photocurrents in photovoltaic devices in combination with PCBM. Preliminary photovoltaic investigation afforded relatively modest power conversion efficiencies of 0.74% (AM 1.5G, 100 mW/cm²), albeit higher than that of previous heteroarylene‐vinylene polymers and comparable to that of P(BDT‐BTD). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of soluble poly(para‐phenylene) with a long polymer chain: Characteristics of regioregular poly(1,4‐phenylene)

Soluble poly(para‐phenylene) having a long polymer chain (more than six repeat units) was synthesized with a tert‐butyl end‐group (t‐PPP) and was found to have improved solubility and excellent optical properties. Poly(1,3‐cyclohexadiene) (PCHD) consisting of only 1,4‐cyclohexadiene (1,4‐CHD) units was synthesized with a tert‐butyl end‐group (t‐PCHD), and completely dehydrogenated to obtain t‐PPP. This end‐group effectively prevented the crystallization of t‐PPP, and polymers containing up to 16 repeat units were soluble in tetrahydrofuran. Soluble t‐PPP obtained had an ability to form a tough thin film prepared by spin‐coating method. Optical analyses of t‐PPP provided strong evidence for a linear polymer chain structure. A block copolymer of t‐PPP and a soluble polyphenylene (PPH) was then synthesized, and the excellent optical properties were retained by this block copolymer along with its solubility. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5223–5231, 2008     

Synthesis of 9,9‐bis(4‐aminophenyl)fluorene‐based benzoxazine and properties of its high‐performance thermoset

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 T_g as high as 236 °C, and the T_g 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