Synthesis of Highly Thermally Stable Daidzein-Based Main-Chain-Type Benzoxazine Resins

The Preparation of an Environmentally Friendly Novel Daidzein-Modified Lignin Phenolic Resin with High Performance and Its Application in Friction Materials

The preparation of biological phenolic resin (PF) with green recyclable biomaterials instead of phenol is a research hotspot for solving current resource and environmental problems. In this study, on the basis of introducing lignin into the phenolic system, daidzein of a renewable resource with a rigid structure was selected to modify lignin-based phenolic resin (LPF), and the improvement of the mechanical and thermal properties of the modified phenolic resin under different substitution ratios was studied. The friction materials were prepared with a daidzein-modified lignin-based phenolic resin (D-LPF) as the matrix binder, and their effects on the mechanics and friction and wear properties of friction materials were investigated. The results show that when the proportion of daidzein replacing phenol is 12%, the highest Tp can reach 152.4 °C, and the Tg of the modified D-LPF resins is significantly higher than those of PF and LPF. The highest Ts of D-LPF is 203.3 °C, which is also significantly higher than those of PF and LPF (184.7 °C and 174.6 °C, respectively). The maximum carbon residue rate at 800 °C is 64.2% and is greatly improved compared with the 55.1% and 56.7% of PF and LPF. The bending strength and impact strength of D-LPF-matrix friction materials are obviously higher than those of PF- and LPF-matrix friction materials. The specific wear rate of D-LPF-matrix friction materials is 0.70 × 10-4 mm3/Nm, which is obviously lower than those of PF- and LPF-matrix friction materials and shows good applicational prospect as a matrix resin in friction materials.

Unlocking daidzein's healing power: Present applications and future possibilities in phytomedicine

BACKGROUND

Cancer is one of the leading causes of death and a great threat to people around the world. Cancer treatment modalities include surgery, radiotherapy, chemotherapy, radiochemotherapy, hormone therapy, and immunotherapy. The best approach is to use a combination of several types. Among the treatment methods mentioned above, chemotherapy is frequently used, but its activity is hampered by the development of drug resistance and many side effects. In this regard, the use of medicinal plants has been discussed, and in recent decades, the use of isolated phytochemicals came into the focus of interest. By critically evaluating the available evidence and emphasizing the unique perspective offered by this review, we provide insights into the potential of daidzein as a promising therapeutic agent, as well as outline future research directions to optimize its efficacy in clinical settings.

PURPOSE

To summarized the therapeutic potential of daidzein, an isoflavone phytoestrogen in the management of several human diseases with the focuses on the current status and future prospects as a therapeutic agent.

METHODS

Several search engines, including PubMed, GoogleScholar, and ScienceDirect, were used, with the search terms "daidzein", "daidzein therapeutic potential", or individual effects. The study included all peer-reviewed articles. However, the most recent publications were given priority.

RESULTS

Daidzein showed protective effects against malignant diseases such as breast cancer, prostate cancer but also non-malignant diseases such as diabetes, osteoporosis, and cardiovascular diseases. Daidzein activates multiple signaling pathways leading to cell cycle arrest and apoptosis as well as antioxidant and anti-metastatic effects in malignant cells. Moreover, the anticancer effects against different cancer cells were more prominent and discussed in detail.

CONCLUSIONS

In short, daidzein represents a promising compound for drug development. The comprehensive potential anticancer activities of daidzein through various molecular mechanisms and its therapeutic/clinical status required further detail studies.

Bio-Based Thermosetting Resins: From Molecular Engineering to Intrinsically Multifunctional Customization

Recent years have witnessed a growing interest in bio-based thermosetting resins in terms of environmental concerns and the desire for sustainable industrial practices. Beyond sustainability, utilizing the structural diversity of renewable feedstock to craft bio-based thermosets with customized functionalities is very worthy of expectation. There exist many bio-based compounds with inherently unique chemical structures and functions, some of which are even difficult to synthesize artificially. Over the past decade, great efforts are devoted to discovering/designing functional properties of bio-based thermosets, and notable progress have been made in antibacterial, antifouling, flame retardancy, serving as carbon precursors, and stimuli responsiveness, among others, largely expanding their application potential and future prospects. In this review, recent advances in the field of functional bio-based thermosets are presented, with a particular focus on molecular structures and design strategies for discovering functional properties. Examples are highlighted wherein functionalities are facilitated by the inherent structures of bio-based feedstock. Perspectives on issues regarding further advances in this field are proposed at the end.

Microporous Carbon and Carbon/Metal Composite Materials Derived from Bio-Benzoxazine-Linked Precursor for CO2 Capture and Energy Storage Applications

There is currently a pursuit of synthetic approaches for designing porous carbon materials with selective CO2 capture and/or excellent energy storage performance that significantly impacts the environment and the sustainable development of circular economy. In this study we prepared a new bio-based benzoxazine (AP-BZ) in high yield through Mannich condensation of apigenin, a naturally occurring phenol, with 4-bromoaniline and paraformaldehyde. We then prepared a PA-BZ porous organic polymer (POP) through Sonogashira coupling of AP-BZ with 1,3,6,8-tetraethynylpyrene (P-T) in the presence of Pd(PPh3)4. In situ Fourier transform infrared spectroscopy and differential scanning calorimetry revealed details of the thermal polymerization of the oxazine rings in the AP-BZ monomer and in the PA-BZ POP. Next, we prepared a microporous carbon/metal composite (PCMC) in three steps: Sonogashira coupling of AP-BZ with P-T in the presence of a zeolitic imidazolate framework (ZIF-67) as a directing hard template, affording a PA-BZ POP/ZIF-67 composite; etching in acetic acid; and pyrolysis of the resulting PA-BZ POP/metal composite at 500 °C. Powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller (BET) measurements revealed the properties of the as-prepared PCMC. The PCMC material exhibited outstanding thermal stability (Td10 = 660 °C and char yield = 75 wt%), a high BET surface area (1110 m2 g-1), high CO2 adsorption (5.40 mmol g-1 at 273 K), excellent capacitance (735 F g-1), and a capacitance retention of up to 95% after 2000 galvanostatic charge-discharge (GCD) cycles; these characteristics were excellent when compared with those of the corresponding microporous carbon (MPC) prepared through pyrolysis of the PA-BZ POP precursors with a ZIF-67 template at 500 °C.

Hebbian Learning on Small Data Enables Experimental Discovery of High Tg Polyimides

We report a study combining computational design and experimental evaluation of polyimides with high glass transition temperatures: T_g between 220 °C and 500 °C. The computational approach is based on the recently introduced competitive learning algorithm, supervised self-organizing maps (SUSI), which we recast as an ensemble method, e-SUSI. We use e-SUSI to solve both unsupervised and supervised/semisupervised learning tasks capturing structure-property relationships of high-T_g polyimides historically studied at Almaden Research Center. Predictors trained on historical data were applied to the combinatorial library of novel polyimides and informed selection of the candidates for synthesis and characterization. In this manner, three new polyimides were prepared with T_g values 281 °C, 282 °C, and 331 °C. The measured values closely agree with the predicted values 273 °C, 311 °C, and 335 °C, respectively. We discuss specific reasons that make the proposed computational design strategy attractive in rapid, deliverable-driven efforts with limited, small-batch data sets.

Thermal properties of polybenzoxazine exhibiting improved toughness: Blending with cyclodextrin and its derivatives

Polybenzoxazines are emerging as a class of high-performance thermoset polymers that can find their applications in various fields. However, its practical application is limited by its low toughness. The cyclic β-cyclodextrin and a newly synthesized derivative (β-cyclodextrin-MAH) were separately blended with benzoxazine to improve the toughness of polybenzoxazine. The results revealed that the maximum impact strength of the blend was 12.24 kJ·m−2 and 14.29 kJ·m−2 when 1 wt.% of β-Cyclodextrin and β-Cyclodextrin-MAH, respectively, were used. The strengths were 53% and 86% higher than that of pure polybenzoxazine. The curing reaction, possible chemical structures, and fractured surface were examined using differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques to understand the mechanism of generation of toughness. The results revealed that the sea-island structure and the presence of hydrogen bonds between polybenzoxazine and β-cyclodextrin and β-cyclodextrin-MAH resulted in the generation of toughness. Furthermore, the curves generated during thermogravimetric analysis did not significantly change, revealing the good thermal properties of the system. The phase-separated structure and the hydrogen bonds present in the system can be exploited to prepare synergistically tough polybenzoxazine exhibiting excellent thermal properties. This can be a potential way of modifying the thermoset resins.

An apigenin-based bio-benzoxazine with three polymerizable functionalities: sustainable synthesis, thermal latent polymerization, and excellent thermal properties of its thermosets

An apigenin-based benzoxazine exhibiting a thermal latent polymerization behavior, high thermal stability and low flammability has been synthesized from sustainable resources.