Benzoxazine Monomer Research Articles

Polybenzoxazine/organosilicon composites with low dielectric constant and dielectric loss

The evolution of electronic communication technology raises higher requirements for low dielectric constant (low-k) materials. For this, a benzoxazine functional organosilicon (HP-aptes) with dense Si—O—Si crosslinking networks and large sterically hindered tert-butyl groups was prepared by the sol–gel method. Then, a series of polybenzoxazine composites (PPHP) were prepared from intrinsically low dielectric constant bis-functional benzoxazine monomer (P-aptmds) and HP-aptes. The double crosslinking networks of polybenzoxazine and organosilicon further increased the crosslinking density and decreased the dipole density of composites, which endowed the composites with enhanced low-k properties. When the content of HP-aptes is 30% (mass), the crosslinking density was 2.05 × 10−3 mol·cm−3, while that of PP-aptmds was 3.31 × 10−3 mol·cm−3. In addition, the dielectric constant and dielectric loss of PPHP composite at 1 MHz could reach 2.61 and 0.0056, respectively.

Synthesis of phosphaphenanthrene-functional monobenzoxazine for enhancing thermal properties of polybenzoxazine thermosets

A facile approach to incorporate an intramolecular 6-membered ring hydrogen bond into a benzoxazine monomer containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) moiety has been developed, leading to a novel monobenzoxazine, ODOPB-pa. This monobenzoxazine was successfully synthesized via a Mannich condensation from 2-(6-oxido-6H-dibenz-[c,e][1,2]oxaphosphorin-1,4-dihydroxy phenylene (ODOPB), propargylamine and paraformaldehyde. The newly obtained ODOPB-pa possesses a relatively lower polymerization temperature than most commercialized benzoxazine resins. In addition, the intramolecular 6-membered ring hydrogen bond is identified as an essential feature in its polymerization behavior. The cured product, poly(ODOPB-pa), exhibits high thermal stability with a 5% weight loss temperature of 327 °C, and good flame retardant properties with a heat release capacity value of 119 Jg−1 K−1 and a total heat release value of 41 kJg−1. Moreover, ODOPB-pa was also applied to mix in different amounts (5, 10, 15 and 20 wt%) with a tri-functional benzoxazine bearing propargyl group, TH-pa. Notably, it has been demonstrated that the TH-pa/ODOPB-pa blend derived thermoset with 10 wt% ODOPB-pa exhibits the best thermal and flame retardant properties in consideration of the high glass transition temperature (312 °C) and very low heat release capacity value (56.5 Jg−1 K−1). These combined advantages highlight the potential of intramolecular 6-membered ring hydrogen bond-containing ODOPB-based benzoxazine in the producing of high-performance thermosetting systems.

Flame-retardant and anti-corrosion behaviour of cardanol-based polybenzoxazine composites

A new monomer of bi-functional benzoxazine was synthesised using cardanol (C) and p-phenylenediamine (ppda) under suitable experimental conditions. The curing behaviour of the cardanol-based 1,4-bis(7-pentadecyl-2H-benzo[1,3]oxazin-3(4H)-yl)benzene (C-ppda) benzoxazine monomer was studied by differential scanning calorimetry analysis, and the polymerisation temperature (T p) of C-ppda benzoxazine was found to be 237°C. Further, the benzoxazine monomer was reinforced with varying weight percentages (5, 10 and 15 wt%) of bio-ash derived from Aerva lanata (AL-ash) to obtain hybrid composites. Thermogravimetric analysis data indicate that AL-ash-reinforced benzoxazine composites possess excellent thermal stability and a flame-retardant behaviour. The morphology of AL-ash- and cardanol-based benzoxazine composites was analysed using field emission scanning electron microscopy (FESEM). The FESEM results indicate homogeneous distribution of AL-ash in the composites. Energy-dispersive X-ray spectroscopy analysis was used to determine the elemental composition of the AL-ash used for the preparation of composites. The value of the water contact angle of poly(C-ppda) was found to be 148°. Data obtained from corrosion studies indicate that the mild steel specimen coated with a benzoxazine matrix and the specimen coated with bio-ash-reinforced benzoxazine composites exhibit an excellent resistance against corrosion. The bio-ash-reinforced composites of cardanol-based benzoxazine can be used in the form of sealants, encapsulants, adhesives, coatings and matrices in microelectronics and automobile applications under high thermal and moist environmental conditions.

Benzoxazine Monomers with Antibacterial Property and Polybenzoxazines for Preventing Adhesion to Bacteria

Benzoxazine Monomers with Antibacterial Property and Polybenzoxazines for Preventing Adhesion to Bacteria

Thermal Stable and Flexible Bio‐Based Polybenzoxazine with Epoxy‐Functionalized Poly(dimethylsiloxane) Hybrids

AbstractIn this study, a monofunctionalized bio‐based benzoxazine monomer (VAnBZ‐CN) is synthesized by condensation of vanillin, formaldehyde, and aniline, and a bifunctional epoxy‐functionalized poly(dimethylsiloxane) (PDMS‐epoxy) is also prepared through hydrosilylation reactions with allyl glycidyl ether. By blending the inorganic PDMS‐epoxy with the VAnBZ‐CN benzoxazine monomer, an organic/inorganic hybrid material is formed, which exhibited enhanced thermal stability after thermal curing polymerization. The improved thermal stability observed in the hybrid material can be attributed to a combination of the formation of the triazine structure by VAnBZ‐CN and the presence of the inorganic part of PDMS‐epoxy on the surface. For example, the PDMS‐epoxy/VAnBZ‐CN = 1/1 hybrid showed the thermal decomposition temperature (Td10) of 309 °C, the glass transition temperature (Tg) of 165 °C, and the char yield of 54 wt.% after the thermal curing polymerization process conducted at 240 °C based on thermogravimetric (TGA) and dynamic mechanical analyses (DMA). Furthermore, the char yield of the hybrid material with PDMS‐epoxy/VAnBZ‐CN = 1/3 is higher than that both of pure VAnBZ‐CN and PDMS‐epoxy after the thermal curing polymerization process. This result indicates that the addition of PDMS‐epoxy resin can improve the formation of a char residue and then enhance the resistance to thermal decomposition for their overall thermal stabilities.

Polybenzoxazine bearing phosphonium and phenol functions catalyzed the cycloaddition of CO2 into epoxide reactions

Polybenzoxazine bearing phosphonium and phenol functions was firstly designed, synthesized, and evaluated for the cycloaddition of CO2 into epoxide (CCE) reactions. Benzoxazine monomers intrinsically installed with phosphonium halide moiety were thermally polymerized to obtain phenolic-type polybenzoxazines. The bifunctional polybenzoxazine catalyst promoted CCE reactions at 120 °C within 2 h to afford high yields up to 96% under atmospheric pressure. The catalyst was recycled four times and maintained 92% yield. A possible bifunctional catalytic mechanism composed of hydrogen-bonding activation by phenol and co-catalysis by halide was proposed and validated. The easy preparation of the benzoxazine monomers with variety of catalytic moieties, and one-step fabrication of the polybenzoxazines suggest untapped potential of manifold polymeric catalyst design and applications.

A bio-based reprocessable and degradable polybenzoxazine with acetal structures

In this work, a bio-based reprocessable and degradable polybenzoxazine with acetal structures was designed and prepared. A diphenol containing acetal structures (DVEA) was reacted with stearylamine and paraformaldehyde to obtain a benzoxazine monomer (DVEA-s). The curing behavior of DVEA-s was investigated using differential scanning calorimetry and in-situ Fourier transform infrared spectroscopy, and the curing kinetics of DVEA-s were also studied. Due to the thermal exchange of acetal structures, the obtained polybenzoxazine (PDVEA-s) exhibited quick stress relaxation. Mechanically crushed PDVEA-s could be reprocessed by hot-pressing at 120 °C for 10 min. Furthermore, the degradation properties of PDVEA-s under different conditions were studied. The results showed that PDVEA-s could be completely degraded in acidic tetrahydrofuran aqueous solution at 50 °C in 4 min.

Preparation of biphenyl-containing polybenzoxazines with low dielectric constants and high thermal stability

In this work, two biphenyl-containing benzoxazine monomers (C-tfmb and C-dmb) have been synthesized using 2,2′-bis(trifluoromethyl)benzidine/2,2′-dimethylbenzidine, 4-cyclohexylphenol and paraformaldehyde as raw materials. The thermal curing behaviors of the benzoxazine monomers were investigated by Fourier transform infrared spectroscopy and non-isothermal differential scanning calorimetry. After curing, the biphenyl-containing polybenzoxazines (PC-tfmb and PC-dmb) exhibited high thermal stability with the 5% weight loss temperatures at 335 °C and 367 °C, respectively. Moreover, both polybenzoxazine films showed high hydrophobicity and low dielectric properties. Due to the presence of low-polarity and bulky cyclohexyl and trifluoromethyl groups, PC-tfmb had a dielectric constant of 2.78 and a dielectric loss of 0.0035 at 1 MHz.

Mechanically Interlocked Vitrimer Based on Polybenzoxazine and Polyrotaxane

A mechanically interlocked vitrimer (MIV) based on a benzoxazine monomer and polyrotaxane (PR) has been prepared through a mechanically interlocked network (MIN) and dynamic covalent bond chemistry. The dynamic transacetalation exchange through the N,O-acetal-type polybenzoxazine (PBz) structure was catalyzed by a tin compound. Compared to the controlled PBz vitrimer without a MIN, the designed PBz MIV shows enhanced mechanical performance including ductility and tensile strength while maintaining relatively high Young’s modulus and glass transition temperature (Tg). The PBz MIV can be reprocessed several times without compromising mechanical performance and thermal stability. The PBz MIV also exhibits a faster dynamic bond exchange and a lower activation energy compared to the controlled PBz vitrimer due to the mobile intramolecular motions of PR in the network allowing for a dynamic bond exchange in the MIV more readily. The usefulness of the present study for the preparation of high-performance eco-friendly thermosetting vitrimers is discussed.

Low-Temperature Terpolymerizable Benzoxazine Monomer Bearing Norbornene and Furan Groups: Synthesis, Characterization, Polymerization, and Properties of Its Polymer.

There is an urgency to produce novel high-performance resins to support the rapid development of the aerospace field and the electronic industry. In the present work, we designed and consequently synthesized a benzoxazine monomer (oHPNI-fa) bearing both norbornene and furan groups through the flexible benzoxazine structural design capability. The molecular structure of oHPNI-fa was verified by the combination characterization of nuclear magnetic resonance spectrum, FT-IR technology, and high-resolution mass spectrum. The thermally activated terpolymerization was monitored by in situ FT-IR as well as differential scanning calorimetry (DSC). Moreover, the low-temperature-curing characteristics of oHPNI-fa have also been revealed and discussed in the current study. Furthermore, the curing kinetics of the oHPNI-fa were investigated by the Kissinger and Ozawa methods. The resulting highly cross-linked thermoset based on oHPNI-fa showed excellent thermal stability as well as flame retardancy (Td10 of 425 °C, THR of 4.9 KJg-1). The strategy for molecular design utilized in the current work gives a guide to the development of high-performance resins which can potentially be applied in the aerospace and electronics industries.

Synthesis and properties of vat photopolymerization 3D-printing benzoxazine

Conventional benzoxazine is difficult for molding and manufacturing parts with complex structures, shaped thin walls, etc. In this work, we presented a new method of synthesizing vat photopolymerization 3D printable benzoxazine inks were proposed to produce high precision constructions with low shrinkage. A creative benzoxazine monomer with excellent printability was synthesized by 2,2′-bis(trif luoromethyl)-4,4′-diaminobiphenyl (TFDB) and Bisphenol AF grafting with isocyanoethyl methacrylate (IEM). Specially, the solvent-free benzoxazine inks have ultra-low shrinkage, line shrinkage up to 1.8%. Minimum printable feature size of 300 µm. This study has solved the problem of benzoxazine being too brittle to be machining. It can be used in aerospace and copper laminate applications.

Synthesis, characterization and protective efficiency of novel polybenzoxazine precursor as an anticorrosive coating for mild steel

In this study, 2-[(E)-(hexylimino)methyl] phenol (SA-Hex-SF) was synthesized by adding salicylaldehyde (SA) and n-hexylamine (Hex-NH2), which was subsequently reduced by sodium borohydride to produce 2-[(hexylamino)methyl] phenol (SA-Hex-NH). Finally, the SA-Hex-NH reacted with formaldehyde to give a benzoxazine monomer (SA-Hex-BZ). Then, the monomer was thermally polymerized at 210 °C to produce the poly(SA-Hex-BZ). The chemical composition of SA-Hex-BZ was examined using FT-IR, 1H, and 13C NMR spectroscopy. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray Diffraction (XRD), respectively, were used to examine the thermal behavior, surface morphology, and crystallinity of the SA-Hex-BZ and its PBZ polymer. Mild steel (MS) was coated by poly(SA-Hex-BZ) which was quickly prepared using spray coating and thermal curing techniques (MS). Finally, the electrochemical tests were used to evaluate the poly(SA-Hex-BZ)-coating on MS as anti-corrosion capabilities. According to this study, the poly(SA-Hex-BZ) coating was hydrophobic, and corrosion efficiency reached 91.7%.

Benzoxazine-grafted-chitosan biopolymer films with inherent disulfide linkage: Antimicrobial properties

Synthesis and fabrication of naturally sourced biopolymers, especially chitosan, grafted with renewable small molecules have recently attracted attention as efficient antimicrobial agents and are highly desired for sustainable material development. Advantageous inherent functionalities in biobased benzoxazine extend the possibility of crosslinking with chitosan which holds immense potential. Herein, a low-temperature, greener facile methodology is adopted for the covalent confinement of benzoxazine monomers bearing aldehyde and disulfide linkages within chitosan to form benzoxazine-grafted-chitosan copolymer films. The association of benzoxazine as Schiff base, hydrogen bonding, and ring-opened structures enabled the exfoliation of chitosan galleries, and such host-guest mediated interactions demonstrated outstanding properties like hydrophobicity, good thermal, and solution stability due to the synergistic effects. Furthermore, the structures empowered excellent bactericidal properties against both E. coli and S. aureus as investigated by GSH loss, live/dead fluorescence microscopy, and morphological alteration on the cell surface by SEM. The work provides the benefits of disulfide-linked benzoxazines on chitosan, offering a promising avenue for general and eco-friendly usage in wound–healing and packaging material.

Synthesis and Characterization of Sustainable Curcumin‐Based Bio‐benzoxazines for Antimicrobial and Anticorrosion Applications

AbstractIn the current study, three novel bio‐based benzoxazines were produced from curcumin (CU), which reacts individually with three different primary amines such aniline (a), furfurylamine (ffa) and octadecylamine (oda) under suitable experimental conditions. FTIR and 1H‐NMR spectra were used to confirm the molecular structure of synthesized curcumin based benzoxazine monomers (CU‐a, CU‐ffa and CU‐oda). It was found that the curing temperatures of the three benzoxazine monomers, CU‐a, CU‐ffa, and CU‐oda are 207 °C, 193 °C, and 199 °C respectively. According to theromogravimetric analysis (TGA) analysis, cured poly(CU‐a), poly(CU‐ffa), and poly(CU‐oda) have remaining char yields of 78, 77, and 55 %, respectively, and their corresponding limiting oxygen index (LOI) values are 49, 48, and 40, respectively, confirming that they have exceptional thermal stability and flame‐retardant qualities that are ideal for applications. The value of water contact angle of poly(CU‐a), poly(CU‐ffa) and poly(CU‐oda) are 131°, 135° and 137° respectively, which infer their excellent hydrophobicity. Results from corrosion and anti‐microbial studies ascertain that these curcumin based benzoxazines can be considered as efficient coating materials to protect the surfaces of mild steel specimen under adverse environmental conditions. Using density‐functional theory (DFT) band gap of the monomers has been calculated and found that CU‐a possesses the lower value of band gap of 2.9212 eV than other benzoxazines.

The effect of preparation conditions of chalcone based benzoxazine/magnetite nanocomposites on magnetization properties

In the current study, a hydroxylated chalcone (1-phenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one, 4-aminobenzoic acid, and paraformaldehyde were combined in ethanol/toluene solvent to form a new benzoxazine monomer. 1H NMR and FTIR analysis were used to confirm the produced monomer. Polybenzoxazine was prepared by the thermal curing of chalcone-based benzoxazine monomer and examined using FTIR and XRD. Magnetite nanoparticles were prepared using two different solvents and mixed with benzoxazine monomer at various ratios, followed by insitu thermal curing to prepare polybenzoxazine/magnetite nanocomposites. These nanocomposites were analyzed by FTIR, XRD, DSC and TGA were used to examine the thermal characteristics of the resulted materials. The surface morphology was investigated using SEM, and the magnetic property was measured by VSM. The resulting benzoxazine monomer has a low curing temperature (160 °C). The addition of nanoparticles of magnetite to benzoxazine improved its thermal stability. Also, the inclusion procedure of magnetite into benzoxazine has a significant impact on its saturation magnetization.

Lead(II) sulfide micro‐crystals doped graphene nanosheets dispersed thermoplastic and multifunctional poly(benzoxazines) cured epoxy resin nanocomposites for medium temperature proton exchange membrane fuel cell applications

AbstractThe amphiphilic polybenzoxazines‐co‐epoxy membrane (POPBOs/PTGP) was created by thermally cross‐linking the multi‐functional octylamine‐based benzoxazine monomer (OPBOs) with synthesized 1,3,5‐tris(oxiran‐2‐yl methoxy)benzene epoxy monomer (TGP). Fourier transform infrared spectroscopy, powder x‐ray diffraction, scanning electron microscopy, and high‐resolution transmission electron microscopy were used to investigate the functionality, crystallinity, and morphology of microcrystal lead(II) sulfide (PbS)/graphene nanosheets (mPbS/GNs). The bare POPBOs/PTGP and different amounts of mPbS/GNs dispersed polymer nanocomposites (PNCs) were obtained from the thermal curing process. Following that, these PNCs were used in medium‐temperature proton exchange membrane fuel cells. The water uptake, ion exchange capacity (IEC), swelling ratio, oxidative stability, and proton conductivity (PC) of bare and loaded mPbS/GNs hybrid nanostructures on POPBOs/PTGP composite membranes were determined. 3 wt% mPbS/GNs distributed with POPBOs/PTGP PNCs exhibit the highest IEC value of 3.61 mmol/g−1 at room temperature, and a PC value of around 6.33 × 10−2 S/cm−1 at 120°C was obtained for the POPBOs/PTGP PNCs. In addition, the single‐cell electrode analysis of the 3 wt% mPbS/GNs‐filled POPBOs/PTGP amphiphilic PNCs showed excellent peak power density and open circuit voltage values of 0.897 W cm−2 and 0.97 V at 120°C.

Synthesis of new biobased benzoxazine through green strategy and its polybenzoxazine resin with high thermal resistance and mechanical strength

AbstractBenzoxazine resins from benzoxazine monomers synthesized with green strategies often do not have high thermal resistance and mechanical strength. Herein, starting from renewable resources citraconic anhydride, furfurylamine and tyramine, a new benzoxazine monomer (CT‐fa) was synthesized and purified in green solvents (ethanol and ethyl acetate), which has excellent molding processability reflected by low melting point (84.9 °C) and low curing temperature (207–245 °C). More attractively, the curedCT‐faresin (poly(CT‐fa)) has both high glass transition temperature (281 °C) and high initial thermal decomposition temperature (407 °C), the former is higher than those of all monofunctional benzoxazine resins synthesized though green strategies in literature, and the latter is even higher than those of all benzoxazine resins synthesized by green strategies (SCI database). In addition,poly(CT‐fa)also has high storage modulus (3955 MPa) and good tensile strength (51.60 MPa). These attractive properties demonstrate thatpoly(CT‐fa)is a promising green high performance resins.

Greening Biobased Polybenzoxazine Network: Three Benefits in One Go

Eco-friendly initiators and environmentally safe flame-retardant (FR) adhesives are highly desired to empower sustainability in polymers. However, incorporating all of the properties simultaneously in a single step is challenging to achieve high-performance biomass sourced polymers. Herein, biobased benzoxazine monomers sourced from agro-waste phenol (cardanol, C) were synthesized using a facile solventless catalyst-free approach. Owing to their requirement of high ROP temperature (∼ 250 °C), prolonged polymerization cycle, issues of high flammability, and poor adhesive strength of the resultant polybenzoxazines limit their applications. To alleviate these issues, blends of naturally occurring phytic acid (PA) with the monomers resulted in fast polymerization kinetics (∼90% monomer conversion in 1 h) with the formation of hybrid polybenzoxazine networks at a mild temperature (∼100 °C). PA enacted as a green initiator and reactive halogen-free biobased FR and revealed favorable interactions across the polymer framework. Benefitting from the design, physical, ionic, and covalent cross-linking network of polymers with PA accounted for the extra-strong adhesive strength (71.1 kg/cm2, nearly 3.7 times higher than that of the pristine polybenzoxazine). Upon burning, the hybrid polybenzoxazines exhibited extremely low flammability, superior smoke suppression and formed intumescent char as supported by the limiting oxygen index, vertical burning, and cone calorimetry measurements. The present study indicated that the benign by design approach is a way forward to green thermosets offering excellent combination properties and potential applications in the future.

Ring Opening Polymerization Used for the Production of VOC Free High-Performance Ecofriendly Novel PBZ/PDA/CeO2 Nanocomposites

This study analyzed the fabrication and characterization of polybenzoxazine/polydopamine/ceria as tertiary nanocomposites. To this end, a new benzoxazine monomer (MBZ) was fabricated based on the well-known Mannich reaction of naphthalene-1-amine, 2-tert-butylbenzene-1,4-diol and formaldehyde under ultrasonic-assisted process. Polydopamine (PDA) was used as dispersing polymer nanoparticles and surface modifier for CeO2 by in-situ polymerization of dopamine with the assistance of ultrasonic waves. Then, nanocomposites (NC)s were manufactured by in-situ route under thermal conditions. The FT-IR and 1H-NMR spectra confirmed the preparation of the designed MBZ monomer. The FE-SEM and TEM results showed the morphological aspects of prepared NCs and illustrated the distribution of CeO2 NPs in the polymer matrix. The XRD patterns of NCs showed the presence of crystalline phases of nanoscale CeO2 in an amorphous matrix. The TGA results reveal that the prepared NCs are classified as thermally stable materials.

Phosphorus-Containing Polybenzoxazine Aerogels with Efficient Flame Retardation and Thermal Insulation.

Bisphenol A type benzoxazine (Ba) monomers and 10-(2, 5-dihydroxyphenyl)-10- hydrogen-9- oxygen-10- phosphine-10- oxide (DOPO-HQ) were employed to prepare flame retardant and heat insulated polybenzoxazine (PBa) composite aerogels. The successful preparation of PBa composite aerogels was confirmed by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The thermal degradation behavior and flame-retardant properties of the pristine PBa and PBa composite aerogels were investigated with thermogravimetric analysis (TGA) and cone calorimeter. The initial decomposition temperature of PBa decreased slightly after incorporating DOPO-HQ, increasing the char residue amount. The incorporation of 5% DOPO-HQ into PBa led to a decrease of 33.1% at the peak of the heat-release rate and a decrease of 58.7% in the TSP. The flame-retardant mechanism of PBa composite aerogels was investigated by SEM, Raman spectroscopy, and TGA coupled with infrared spectrometry (TG-FTIR). The aerogel has advantages such as a simple synthesis procedure, easy amplification, lightweight, low thermal conductivity, and good flame retardancy.