Search Results (214)

A naturally sourced phenolic compound, umbelliferone, has been used to synthesize four monofunctional benzoxazines, two of which have been previously synthesized from aniline and furfurylamine. This study contributes two more—using benzylamine and phenethylamine—to provide insight into how the amine’s aromatic group and aliphatic chain length influence resulting properties. The proposed chemical structures of the novel monomers are confirmed by ¹H nuclear magnetic resonance (¹H-NMR) and ¹H-¹H nuclear Overhauser effect spectroscopy (NOESY). The polymerization behavior of each resin is determined by differential scanning calorimetry (DSC). The thermal degradation pattern and the flammability of each polymer are assessed by thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC), respectively. Char yields between 49% and 63% suggest the thermoset materials to be thermally stable and competitive for thermally demanding applications. All four polybenzoxazines demonstrate non-ignitable behavior, with heat release capacities below 100 J/g·K. Structure–property analyses on the two newly synthesized compounds have been provided to deepen our existing understanding of umbelliferone-benzoxazine systems, particularly regarding the effect of the aminic moiety on thermal properties. Full article

Acylpyruvate derivatives represent a promising yet underexplored class of compounds for modulating microalgal growth and metabolism. Inspired by the metabolic role of pyruvate and the diverse bioactivity of its acylated analogs, this study investigates the structure–activity relationship of a diverse library of 55 acylpyruvate-derived compounds for stimulation of the green microalga Chlorella vulgaris. The library, encompassing 12 chemotypes including acylpyruvic acids, their esters, and various heterocyclic derivatives, was screened for effects on C. vulgaris growth. Six compounds were identified as active ones that enhanced biomass production in a preliminary microassay. Notably, four of these active compounds were direct acylpyruvate derivatives, highlighting this scaffold as the most promising one. Conversely, a specific subclass, 1,4-benzoxazin-2-ones, exhibited potent, dose-dependent algicidal activity. Detailed assessment of the active compounds under scaled-up culture conditions revealed that while their effect on overall cell density was limited, several compounds significantly enhanced the intracellular content of valuable metabolites: one increased chlorophyll content by 17%, another elevated carotenoids by 40%, and a third boosted neutral lipid accumulation by 44%. Furthermore, control experiments confirmed that the bioactivity of p-ethoxybenzoylpyruvates, which showed the best biological activity, is inherent in the intact framework and is not mediated by their hydrolysis products. Our findings underscore the potential of acylpyruvates as versatile tools for the enhancement of metabolite production in microalgae and as potent candidates for the development of algicides. Full article

In this study, the blends of bio-based polybenzoxazine (V-fa type) and poly(ethylene glycol) (PEG) with PEG contents from 50 to 95 wt% and different molecular weights were developed to improve the flexibility of thermosetting polymers. Of these blends, PEG 8k at 80 wt%, which exhibited the best processability, was selected for further development via compositing with carbon black (CB) from 0 to 20 phr. Differential Scanning Calorimetry (DSC) analysis revealed that the melting temperature (T_m) increased from 70 to 83 °C and glass transition temperatures (T_g) increased from –53 to –48 °C at 20 phr. Thermogravimetric Analysis (TGA) demonstrated high thermal stability, with T_dmax (for all CB contents) presented at ca. 416 °C. Moreover, char yield was increased from 10% (without CB) to 28% (20 phr), reflecting improved decomposition resistance. Mechanical properties demonstrated that CB significantly reinforced the composites. The flexural modulus and flexural strength were increased from 117.18 MPa (without CB) to 456 MPa (10 phr) and from 2.42 MPa (without CB) to 3.94 MPa (2.5 phr), respectively. The SEM images confirmed uniform morphology and good filler dispersion. Conclusively, the composites of 8k PEG 80 wt% filled with 2.5 phr of CB provided an optimal balance of mechanical and thermal stability and engineering polymer applications. Full article

Background/Objectives: Targeted cancer therapies increasingly rely on modulating specific cell death pathways and kinase signaling. Due to their structural versatility and potential to induce mechanistically distinct cytotoxic responses, benzoxazine–purine hybrids represent a promising scaffold for anticancer drug development. The objective of this study was to design and evaluate novel benzoxazine–purine derivatives for their antiproliferative activity and elucidate their underlying mechanisms of action. Methods: A series of benzoxazine–purine compounds was synthesized via a modular and efficient approach. The synthetic route involved a one-pot cyclization of substituted 2-aminophenols with epichlorohydrin, followed by tosylation and subsequent Mitsunobu coupling with halogenated purines. Their antiproliferative activity was assessed in MCF-7 (breast) and HCT-116 (colon) cancer cell lines using MTT assays. Selected compounds were evaluated further for kinase inhibition, effects on the cell cycle, membrane integrity (Annexin V/PI staining), ultrastructural changes (SEM), and caspase activation (Western blot). In silico ADMET profiling was also performed. Results: Compounds 9 and 12 exhibited the most potent antiproliferative activity, with low micromolar IC₅₀ values. Compound 12 showed dual HER2/JNK1 kinase inhibition and induced caspase-8-dependent pyroptosis-like cell death, characterized by membrane rupture and inflammatory features. In contrast, compound 8 lacked kinase inhibition and promoted S-phase arrest with apoptotic-like morphology. Both compounds demonstrated favorable physicochemical and ADMET profiles, including high intestinal absorption and an absence of mutagenicity. Conclusions: The rational design of benzoxazine–purine hybrids resulted in the discovery of compounds with distinct mechanisms of action. Compound 12 induces inflammatory cell death by modulating kinases, while compound 9 acts through a kinase-independent apoptotic pathway. These results underscore the therapeutic potential of scaffold-based diversification for developing targeted anticancer agents. Full article

A novel quinoline-containing benzoxazine resin, 8HQ-fa, has been successfully synthesized at room temperature using sustainable raw materials, such as 8-hydroxyquinoline and furfurylamine as the phenol and amine source, respectively. The chemical structure of the hereinafter referred to as quinolinoxazine is fully characterized by Fourier transform infrared spectroscopy (FT-IR), ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR), as well as by 2D ¹H–¹H nuclear Overhauser effect spectroscopy (NOESY) and ¹H–¹³C heteronuclear multiple quantum correlation (HMQC) NMR. Thermal properties and polymerization behavior of the monomer are studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The resulting polymer is also characterized in terms of its thermal and fire-related properties by DSC, TGA, and microscale combustion calorimetry (MCC). The resulting thermoset, poly(8HQ-fa), presents good thermal stability as evidenced by its T_g (201 °C), T_d5 and T_d10 (307 and 351 °C, respectively), and char yield (42%), and low flammability as determined by the LOI, heat release capacity, and total heat released values (34.3, 143 J/gK, and 10.8 kJ/g, respectively), making it a self-extinguishing thermoset. The combination of properties and advantages in the synthesis of 8HQ-fa, accompanied by a low polymerization temperature, suggests its great potential in the field of high-performance polymers. Full article

To impart high flame resistance, enhanced thermal stability, and low dielectric properties to epoxy resin while maintaining good mechanical behaviors for high-end applications, a monomer (BZPN) containing the characteristic structure of benzoxazine, phthalonitrile, and trifluoromethyl was prepared and added into the Bisphenol A-type epoxy resin (DGEBA)/Dapsone (DDS) combination. The glass transition temperature (T_g) and carbon yield under a nitrogen atmosphere at 800 °C were found to significantly increase from 155 °C, 17.2% to 236 °C, 50.3%, respectively, for the neat EP/DDS and the BZPN-containing material. The UL-94 flammability rating achieved V-0 level when the BZPN content was 19.2 wt.% (EP-BZ-1). The thermal decomposition and flame retardancy mechanism were explored by TGA-FTIR, Raman, and XPS analysis. The fluorine-containing products were found in both the gas phase and the char residue, implying that the •CF₃ radicals played an important role in promoting the flame-retardant behaviors through a radical trapping mechanism. The dielectric constant and dielectric loss of the materials decreased as anticipated. In addition, mechanical testing of carbon fiber-reinforced composites showed that the BZPN-containing resin presented equivalent mechanical behaviors to the neat EP/DDS resin. The synthesized BZPN was proved to be an effective and promising additive for the epoxy-based composite. Full article

Hybrid thermosetting terpolymers based on epoxidized linseed oil (ELO), eugenol-based benzoxazine monomer (EPB), and thiols (2SH and 3SH) were synthesized and studied by focusing on the effects of the thiol-bearing functionality over the final performances. The curing dynamics were monitored by differential scanning calorimetry (DSC) and Fourier transform infrared spectrometry (FTIR). FTIR results showed that the curing process takes place in multiple steps and depends on the concentration of thiol used as a crosslinker. At the same time, the complexity of the reactions that take place within each system was highlighted by the curing profiles from DSC. Dynamic mechanical analysis (DMA) and nanoindentation data revealed that the mechanical features of the terpolymers can be modulated to achieve high stiffness, as in the case where 2SH and 3SH thiols were used in 0.25 wt.% or increased flexibility where 1% thiol concentrations were employed. Higher crosslinking density for hybrid terpolymers in comparison with the epoxy/benzoxazine sample indicated a good compatibility between the monomers and the crosslinking agents and the formation of additional chemical bonds within the networks. The ternary samples demonstrated good thermal stability (up to 300 °C) and high residual mass (>25%), which make them suitable candidates as flame-resistant coatings. Full article

Benzoxazine resins are gaining attention for their impressive thermal stability, low water uptake, and strong mechanical properties. In this work, two new bio-based benzoxazine monomers were developed using renewable arbutin: one combined with 3-(2-aminoethylamino) propyltrimethoxysilane (AB), and the other with furfurylamine (AF). Both were synthesized using a simple Mannich-type reaction and verified through FT-IR and ¹H-NMR spectroscopy. By blending these monomers in different ratios, copolymers with adjustable thermal, dielectric, and surface characteristics were produced. Thermal analysis showed that the materials had broad processing windows and cured effectively, while thermogravimetric testing confirmed excellent heat resistance—especially in AF-rich blends, which left behind more char. The structural changes obtained during curing process were monitored using FT-IR, and XPS verified the presence of key elements like carbon, oxygen, nitrogen, and silicon. SEM imaging revealed that AB-based materials had smoother surfaces, while AF-based ones were rougher; the copolymers fell in between. Dielectric testing showed that increasing AF content raised both permittivity and loss, and contact angle measurements confirmed that surfaces ranged from water-repellent (AB) to water-attracting (AF). Overall, these biopolymers (AB/AF copolymers) synthesized from arbutin combine environmental sustainability with customizability, making them strong candidates for use in electronics, protective coatings, and flame-resistant composite materials. Full article

Exploration of new ways for the direct preparation of cross-linked structures is a significant problem in terms of materials for biomedical applications, lithium batteries electrolytes, toughening of thermosets (epoxy, benzoxazine, etc.) with interpenetrating polymer network, etc. The possibility to utilize hydrosilylation and Piers–Rubinsztajn reactions to obtain cross-linked model phosphazene compounds containing eugenoxy and guaiacoxy groups has been studied. It was shown that Piers–Rubinsztajn reaction cannot be used to prepare phosphazene-based tailored polymer matrix due to the catalyst deactivation by nitrogen atoms of main chain units. Utilizing the hydrosilylation reaction, a series of cross-linked materials were obtained, and their properties were studied by NMR spectroscopy, FTIR, DSC, and TGA. Rheological characterizations of the prepared tailored matrices were conducted. This work showed a perspective of using eugenoxy functional groups for the preparation of three-dimensional hybrid phosphazene/siloxane-based materials for various applications. Full article

Corrosion is a major issue in many industries, leading to material degradation, increased maintenance costs, and safety hazards. Conventional protective coatings frequently rely on hazardous chemicals, which has driven demand for environmentally friendly materials that can enhance the durability of infrastructure. The present study investigates the structural, mechanical, anticorrosive, and tensile properties of a novel polymer composite based on tannic acid-benzoxazine monomer (TA-BZ), reinforced with epoxy resin and zinc oxide (ZnO) nanoparticles. The composite formulations are designated as Epoxy-TA-BZ1-ZnO (A), Epoxy-TA-BZ2-ZnO (B), and Epoxy-TA-BZ4-ZnO (C). The objective of this research is to develop a sustainable material system with improved anticorrosive and mechanical performance. The composites were synthesized through the crosslinking of TA-BZ with epoxy resin and the incorporation of ZnO nanoparticles, known for their corrosion-inhibiting properties and contributions to tensile strength. The materials were evaluated using Fourier Transform Infrared (FT-IR) spectroscopy, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), potentiodynamic polarization techniques, and tensile testing. Among the tested formulations, Epoxy-TA-BZ4-ZnO exhibited outstanding anticorrosive performance, achieving a minimal corrosion rate of 0.06 mm/year. This performance is attributed to the favorable dispersion of ZnO nanoparticles at 5 wt%, which serve as effective barriers to corrosive agents under the conditions studied. These findings highlight the potential of TA-BZ-based composites as environmentally sustainable alternatives to conventional coatings in corrosion-sensitive applications. Full article

Benzoxazines are a kind of high-performance thermosetting resin that can undergo ring-opening polymerization to generate cross-linking structures. Here, two benzoxazine monomers, bisphenol A/aniline type (BA-a) and bisphenol A/tert-butylamine type (BA-tb), were synthesized and mixed with three tertiary amine catalysts like 2-methylimidazole (2MI), 1,2-dimethylimidazole (12MI), 4-dimethylaminopyridine (DMAP). Differential scanning calorimetry (DSC) was performed to study the curing behaviors and the curing kinetics of two benzoxazine/catalyst systems. The results indicated that all amines had a catalytic effect on the polymerization of both benzoxazines, and the BA-a/catalyst systems showed relatively higher activity. In addition, Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectra were procured to analyze structural changes in the benzoxazine/catalyst systems during the curing process. The presence of the catalysts promoted the progress of the ring-opening reactions and the formation of the phenolic units in the cross-linking structures, and these evolutions were more obvious for the BA-a/catalyst system than the BA-tb/catalyst system. Furthermore, a thermogravimetric analysis (TGA) was conducted to analyze the thermal stability of the cured systems. Finally, possible curing reaction mechanisms were proposed for these benzoxazine/amine systems. Full article

Marine antifouling coatings that rely on the release of antifouling agents are the most prevalent and effective strategy for combating fouling. However, the environmental concerns arising from the widespread discharge of these agents into marine ecosystems cannot be overlooked. An innovative and promising alternative involves incorporating antimicrobial groups into polymers to create coatings endowed with intrinsic antimicrobial properties. In this study, we reported an urushiol-based benzoxazine (URB) monomer, synthesized from natural urushiol and antibacterial rosin amine. The URB monomer was subsequently polymerized through thermal curing ring-opening polymerization, resulting in the formation of a urushiol-based benzoxazine polymer (URHP) coating with inherent antimicrobial properties. The surface of the URHP coating is smooth, flat, and non-permeable. Contact angle and surface energy measurements confirm that the URHP coating is hydrophobic with low surface energy. In the absence of antimicrobial agent release, the intrinsic properties of the URHP coating can effectively kill or repel fouling organisms. Furthermore, with bare glass slides serving as the control sample, the coating demonstrates outstanding anti-adhesion capabilities against four types of bacteria (E. coli, S. aureus, V. alginolyticus, and Bacillus sp.), and three marine microalgae (N. closterium, P. tricornutum, and D. zhan-jiangensis), proving its efficacy in preventing fouling organisms from settling and adhering to the surface. Thus, the combined antibacterial and anti-adhesion properties endow the URHP coating with superior antifouling performance. This non-release antifouling coating represents a green and environmentally sustainable strategy for antifouling. Full article

In this study, a novel bio-based oxazine resin was synthesized through the reaction of naturally renewable materials: cardanol and furfurylamine. The molecular structure of the target product was confirmed via comprehensive characterization techniques, including Fourier-transform Infrared Spectroscopy (FT-IR), Gel Permeation Chromatography (GPC), Mass Spectrometry (MS), and Nuclear Magnetic Resonance (NMR). Differential Scanning Calorimetry (DSC) revealed that the curing process of cardanol-furfurylamine oxazine (CFZ) exhibited three exothermic peaks (~140, ~240, ~270 °C), which not only helped to optimize the processing conditions but also effectively enhanced the material properties. In the modification experiments, CFZ had been blended and cured with benzoxazine (BZ) at the mass ratios of 2:98, 5:95, 10:90, 20:80, and 40:60. Dynamic Mechanical Thermal Analysis (DMTA) further showed an elevated Loss Factor (tan δ) peak of CFZ-BZ resin, suggesting significantly enhanced toughness. Notably, when the content of the CFZ resin in the composite reached only 5%, the storage modulus achieved its maximum value, highlighting that minimal addition of CFZ resin can optimize the rigidity of the composite, which would drastically reduce material costs and simplify the process. Impact strength testing demonstrated that the impact resistance of CFZ-BZ resin was 6.42 times higher than that of pristine BZ. By integrating renewable materials with rational molecular design, this novel oxazine resin synergistically combines high-temperature resistance, superior toughness, and efficient modification at low loading, positioning it as a promising candidate to replace conventional petroleum-based resins in aerospace, renewable energy, and electronic packaging applications. Full article

This review explores the structural and electrochemical characteristics of carbon materials derived from polybenzoxazines, emphasizing their potential in supercapacitors. A detailed analysis of thermal degradation by-products during carbonization reveals distinct competing mechanisms, underscoring the exceptional thermal stability of benzoxazines. These materials exhibit significant pseudocapacitive behavior and excellent charge retention, making them strong candidates for energy storage applications. The versatility of polybenzoxazine-based carbons enables the formation of diverse morphologies—nanospheres, foams, films, nanofibers, and aerogels—each tailored for specific functionalities. Advanced synthesis techniques allow for precise control over porosity at the nanoscale, optimizing performance for supercapacitors and beyond. Their exceptional thermal stability, electrical conductivity, and tunable porosity extend their utility to gas adsorption, catalysis, and electromagnetic shielding. Additionally, their intumescent properties (unique ability to expand when exposed to high heat) make them promising candidates for flame-retardant coatings. The combination of customizable architecture, superior electrochemical performance, and high thermal resistance highlights their transformative potential in sustainable energy solutions and advanced protective applications. Full article

Glass fiber-reinforced polymer (GFRP) composites are widely utilized across industries, particularly in structural components exposed to hygrothermal environments characterized by elevated temperature and moisture. Such conditions can significantly degrade the mechanical properties and structural integrity of GFRP composites. Therefore, it is essential to utilize effective methods for assessing their hygrothermal aging. Traditional approaches to hygrothermal aging evaluation are hindered by several limitations, including time intensity, high costs, labor demands, and constraints on specimen size due to laboratory space. This study addresses these challenges by introducing a facile and efficient alternative that evaluates GFRP degradation under hygrothermal conditions through surface wettability analysis. Herein, a glass fiber-reinforced benzoxazine (BZ) composite was fabricated using the vacuum-assisted resin transfer molding (VARTM) method and was aged in a controlled humidity and temperature chamber for up to 5 weeks. When analyzing the wettability characteristics of the composite, notable changes in the contact angle (CA) and contact angle hysteresis (CAH) were 21.77% and 90.90%, respectively. Impact droplet dynamics further demonstrated reduced wetting length and faster droplet equilibrium times with the prolonged aging duration, indicating a progressive decline in surface characteristics. These changes correlated with reductions in flexural strength, highlighting the surface’s heightened sensitivity to environmental degradation compared with internal structural integrity. This study emphasizes the critical role of surface characterization in predicting the overall integrity of GFRP composites. Full article