Synthesis and properties of biobased mono-benzoxazine resins from natural renewable pterostilbene

Synthesis of Renewable Furan-Based Benzoxazines and Polybenzoxazines: Recent Advances

The burgeoning field of materials science is currently witnessing a paradigm shift toward the utilization of renewable plant biomass as a viable chemical source for the production of sustainable materials. This trend is substantiated by a significant corpus of recent experimental and theoretical research focused on the synthesis and property analysis of such polymers. Within this context, polybenzoxazines stand out as a pioneering class of thermosetting polymers, distinguished by their exceptional thermal and mechanical characteristics, coupled with the feasibility of synthesizing their precursor monomers from eco-friendly, renewable resources, including plant phenols and furfurylamine. Opting for furfurylamine over traditional aniline and its petroleum-derived counterparts in the synthesis of benzoxazines not only increases the eco-compatibility of the resultant materials but also imparts a significant alteration to their properties. This short review, spanning the last three years, delves into the principal advancements achieved in the realm of novel furan-bearing benzoxazines and polybenzoxazines from 2021 to present, accentuating both the triumphs and challenges encountered in this burgeoning domain.

Synthesis and Characterization of Bio-based Polybenzoxazine Hybrids From Vanillin, Thymol, and Carvacrol

Recently, the fast advancement of bio-based polymers has boosted the interest in green and sustainable materials. In this context, polybenzoxazine-derived renewable resources have been widely investigated due to their environmental benefits and high mechanical and thermal properties. This study focused on synthesizing hybrid benzoxazines from bio-phenolic compounds- vanillin, thymol, and carvacrol- combined with Jeffamine D-230 and paraformaldehyde. The chemical structures of hybrid benzoxazines (Van-JD, Thy-JD, and Car-JD) were characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR). Furthermore, the curing behavior and thermal stability of synthesized bio-phenolic-based benzoxazines were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

Partially Bio-Based Benzoxazine Monomers Derived from Thymol: Photoluminescent Properties, Polymerization Characteristics, Hydrophobic Coating Investigations, and Anticorrosion Studies

In this work, four thymol-based benzoxazines were synthesized using four primary amines with different chain lengths, namely methylamine, ethylamine, 1-propylamine, and 1-butylamine, which are then named T-m, T-e, T-p, and T-b, respectively. The optical properties of the synthesized thymol-based benzoxazines were examined via the photoluminescent study of their solutions in acetone. The results show that all the prepared benzoxazines emitted blue light with the maximum wavelengths from 425 to 450 nm when irradiated by the excitation wavelengths from 275 to 315 nm. The maximum excitation wavelengths are found to be 275 nm. The polymerization of the thymol-based benzoxazines is triggered by heat treatments with different conditions (160, 180, and 200 °C for 1 h). According to the FTIR results, the heat-curing process introduces a presence of the OH peak, of which intensity increases as the curing temperature increases. Thermal decompositions of thymol-based benzoxazines regarding TGA analyses reveal the enhancement of thermal stability of the benzoxazines with respect to the N-substituent chain length, as significantly observed the change in the first thermal decomposition at temperature ranged from 253 to 260 °C. Synthesized benzoxazine derivatives are further employed to coat the substrate, e.g., the glass slides. The investigation of the water contact angle shows that the coating of the benzoxazines onto the surface improves the hydrophobicity of the substrate, resulting in the enlargement of the contact angle from 25.5° to 93.3°. Moreover, the anticorrosion performance of the polybenzoxazine coatings is examined using potentiodynamic polarization techniques. The results illustrate the anticorrosion efficiency of the thymol-based polybenzoxazine up to 99.99%. Both hydrophobic and electrochemical studies suggest the feasibility for employing benzoxazines in anticorrosion coating applications.

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 (T_d10 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.

Recent advances in the development of green furan ring-containing polymeric materials based on renewable plant biomass

Fossil resources are rapidly depleting, forcing researchers in various fields of chemistry and materials science to switch to the use of renewable sources and the development of corresponding technologies. In this regard, the field of sustainable materials science is experiencing an extraordinary surge of interest in recent times due to the significant advances made in the development of new polymers with desired and controllable properties. This review summarizes important scientific reports in recent times dedicated to the synthesis, construction and computational studies of novel sustainable polymeric materials containing unchanged (pseudo)aromatic furan cores in their structure. Linear polymers for thermoplastics, branched polymers for thermosets and other crosslinked materials are emerging materials to highlight. Various polymer blends and composites based on sustainable polyfurans are also considered as pathways to achieve high-value-added products.