A Comprehensive Review on Bio-Based Polybenzoxazines Emphasizing Their Antimicrobial Property

Polybenzoxazines (PBzs), a class of high-performance thermosetting polymers, have gained significant attention for their exceptional thermal stability, mechanical properties, and chemical resistance, making them ideal for aerospace, electronics, and biomedical applications. Recent advancements emphasize their antimicrobial potential, attributed to unique structural properties and the ability to incorporate bio-active functional groups. This review highlights the synthesis, antimicrobial mechanisms, and applications of PBzs and their bio-based derivatives, focusing on sustainable materials science. PBzs demonstrate antimicrobial efficacy through mechanisms such as hydrophobic surface interactions and reactive functional group formation, preventing microbial adhesion and biofilm development. The incorporation of functional groups like amines, quaternary ammonium salts, and phenolic moieties disrupts microbial processes, enhancing antimicrobial action. Modifications with metal nanoparticles, organic agents, or natural bio-actives further augment these properties. Notable bio-based benzoxazines include derivatives synthesized from renewable resources like curcumin, vanillin, and eugenol, which exhibit substantial antimicrobial activity and environmental friendliness. Hybrid PBzs, combining natural polymers like chitosan or cellulose, have shown improved antimicrobial properties and mechanical performance. For instance, chitosan-PBz composites significantly inhibit microbial growth, while cellulose blends enhance film-forming capabilities and thermal stability. PBz nanocomposites, incorporating materials like silver nanoparticles, present advanced applications in biomedical and marine industries. Examples include zirconia-reinforced composites for dental restoration and urushiol-based PBzs for eco-friendly antifouling solutions. The ability to customize PBz properties through molecular design, combined with their inherent advantages such as flame retardancy, low water absorption, and excellent mechanical strength, positions them as versatile materials for diverse industrial and medical applications. This comprehensive review underscores the transformative potential of PBzs in addressing global challenges in antimicrobial material science, offering sustainable and multifunctional solutions for advanced applications.

A lysosome-targetable fluorescent probe for the ratiometric detection of formaldehyde in living cells and in vivo

Inspired by the synthetic method of benzoxazine derivatives and our previous research, a fluorescent probe (SWJT-6) was designed for formaldehyde (FA) detection based on the cyclization reaction. The synthetic SWJT-6 showed excellent colorimetric and ratiometric response to formaldehyde, and could be perfectly used as test strips to detect formaldehyde. It also showed a fast detection time (3 min), low detection limit (5.65 μM) and high selectivity for formaldehyde within various interfering analytes. In addition, SWJT-6 has been successfully applied in bioimaging of intracellular and lysosomal formaldehyde in both HeLa cells and zebrafish.

Recent advances in bio-based polybenzoxazines as an interesting adhesive coating

Polybenzoxazine (PBz) is an excellent and highly intriguing resin for various sophisticated uses. Benzoxazines have piqued the curiosity of academics worldwide because of their peculiar properties. Nonetheless, most benzoxazine resin manufacturing and processing methods, notably bisphenol A-based benzoxazine, rely on petroleum resources. Because of the environmental consequences, bio-based benzoxazines are being researched as alternatives to petroleum-based benzoxazines. As a result of the environmental implications, bio-based benzoxazines are being developed to replace petroleum-based benzoxazines, and they are gaining traction. Bio-based polybenzoxazine, epoxy, and polysiloxane-based resins have piqued the interest of researchers in coatings, adhesives, and flame-retardant thermosets in recent years due to their anticorrosion, ecologically friendly, affordable, and low water absorption properties. As a result, numerous scientific studies and patents on polybenzoxazine continues to rise in polymer research. Based on its mechanical, thermal, and chemical characteristics, bio-based polybenzoxazine has several applications, including coatings (anticorrosion and antifouling), adhesives (highly crosslinked network, outstanding mechanical and thermal capabilities), and flame retardants (with the high charring capability). This review reports an overview of polybenzoxazine, highlighting the current advances and progress in synthesizing bio-based polybenzoxazine, their properties, and their use in coating applications.

Well-defined benzoxazine/triphenylamine-based hyperbranched polymers with controlled degree of branching

Well-defined thermally polymerizable hyperbranched polymers (TPA–BZs) containing various numbers of triphenylamine (TPA) and benzoxazine (BZ) units have been prepared using a “click-like” reaction concept, through one-pot Mannich condensations of 4-(bis(4-aminophenyl)amino)phenol (TPA–2NH₂–OH, as the AB₂ branching groups), aniline (as the focal groups), CH₂O, and phenol in 1,4-dioxane, with a unique feeding approach. Two design strategies for the chemical construction were applied: (i) simple hyperbranched TPA–BZs, such as those containing one or three TPA units, developed from the focal or the terminal group direction to form the resultant monomers; (ii) three dendritic TPA–BZs containing four TPA units possessing different degrees of branching (DBs) for the conformation study. The exothermic temperature for the dendritic TPA–BZs decreased upon increasing the DB. The bathochromic shifts of the dendritic TPA–BZs increased upon increasing the number of TPA units, in UV-Vis absorption and PL emission spectra, presumably because of an increase in the effective conjugation length. In addition, the polymerized dendritic TPA–BZ DG1 possessed thermal properties superior to those of the hyperbranched TPA–BZ polybenzoxazines, possibly because the segmental mobility in the polymer network was restricted by the dendrimer core group and because of its symmetrical construction. The hyperbranched TPA–BZ possessed unique photophysical properties, suggesting potential applications in optoelectronic devices.

Different well-defined benzoxazine/triphenylamine based hyperbranched polymers with controlled degree of branching were prepared and discussed.

Benzoxazine/Triphenylamine-Based Dendrimers Prepared through Facile One-Pot Mannich Condensations

A series of thermally polymerizable dendrimers of various generations, equipped with triphenylamine (TPA) and benzoxazine (BZ) groups, is synthesized through facile one-pot Mannich condensations of N¹ ,N¹ -bis(4-aminophenyl)benzene-1,4-diamine (TPA-3NH₂ , as the core group), 4-(bis(4-aminophenyl)amino)phenol (TPA-2NH₂ -OH, as the AB₂ branching group), and CH₂ O in 1,4-dioxane. The ratios of the integrated areas in the ¹ H nuclear magnetic resonance spectra of these dendrimers are consistent with the theoretical numbers of protons, suggesting their successful syntheses. Bathochromic shifts of signals are evident in the UV-vis and photoluminescence spectra upon increasing the generation of the TPA-BZ dendrimers, consistent with an increase in the effective conjugation length. The TPA-BZ dendrimers are able to undergo thermal polymerization and display unique optical physical properties, resulting in thermoset TPA networks after thermal ring-opening polymerization.