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[Display omitted] • The facile preparation of PBz aerogel with excellent thermal insulation performance is realized. • The char yields of PBz aerogel reach 55.00 % at 600 °C. • The obtained PBz aerogel demonstrates a low thermal conductivity of 0.0313 W m−1 K−1 at 25 °C. • The obtained PBz aerogel exhibits super-hydrophobicity and outstanding mechanical properties. Polybenzoxazine (PBz) aerogels with outstanding mechanical properties and thermal insulation have attracted significant attention because of their classification as the most advanced and efficient thermal insulation material. However, the complex and environmentally unfriendly preparation technology has consistently hindered the performance improvement and broad practical applications of PBz aerogels. Herein, we report a facile preparation method of PBz aerogels through an aqueous solution system and ambient pressure drying (APD), thereby overcoming the limitations of the conventional methods. The resulting PBz aerogel exhibits lightweight (0.194 g cm−3), efficient thermal insulation, low thermal conductivity (0.0313 W m−1 K−1), self-extinguishing, super-hydrophobicity (contact angle of 148°), and remarkable mechanical properties. This study proposes a cutting-edge approach to fabricate PBz aerogels, which further amplifies their potential application in the field of thermal insulation. [ABSTRACT FROM AUTHOR]

The unremitting pursuit of high-performance and multifunctional materials has consistently propelled modern industries forward, stimulating research and motivating progress in related fields. In such materials, polybenzoxazine (PBz) aerogel, which combines the virtues of PBz and aerogel, has attracted salient attention recently, emerging as a novel research focus in the realm of advanced materials. In this review, the preparation scheme, microscopic morphology, and fundamental characteristics of PBz aerogels are comprehensively summarized and discussed in anticipation of providing a clear understanding of the correlation between preparation process, structure, and properties. The effective strategies for enhancing the performance of PBz aerogels including composite fabrication and hybridization are highlighted. Moreover, the applications of PBz-based aerogels in various domains such as adsorption (including wastewater treatment, CO 2 capture, and microwave adsorption), thermal insulation, energy storage as well as sensors are covered in detail. Furthermore, several obstacles and potential directions for subsequent research are delineated with a view to surmounting the prevailing constraints and achieving a realization of the shift from experimental exploration to practical applications. [Display omitted] • Polybenzoxazine (PBz) aerogels present a wide-ranging potential for applications as emerging high-performance materials. • Elaborate summaries of preparation routes for PBz aerogels. • The microscopic morphology of PBz aerogels can be modulated through colloid chemistry principles. • Comprehensive introduction of composite and hybrid materials based on PBz aerogels. • Challenges and potential development directions faced by PBz aerogels. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lightweight polybenzoxazine (PBz) aerogels were fabricated by hexamethylene diisocyanate (HDI) modification. • The introduction of HDI formed a covalent-crosslinked structure with the chemical structure of the PBz aerogel. • The HDI-modified PBz aerogel demonstrates a self-extinguishing time of less than 1 s after removal from a 1200 °C flame. The rapid advancement of modern industries has imposed demands on thermal insulators that possess not only low thermal conductivities but also multifunctional properties. Polybenzoxazine (PBz) aerogels with several advantages have garnered considerable research interest in recent years. Nevertheless, PBz aerogels acquired from ambient pressure drying still confront the challenge of exhibiting relatively high densities and thermal conductivities. In this study, to enrich the category and propose practical ideas for overcoming the above plight, hexamethylene diisocyanate (HDI) was selected as an additive to prepare lightweight and efficient thermal-insulating PBz aerogels through chemical modification. Compared with the pristine specimens (0.268 g·cm−3, 0.0387 W·m−1·K−1), the HDI-modified PBz aerogels exhibited lower densities (0.237–0.256 g·cm−3) and thermal conductivities (0.0354–0.0370 W·m−1·K−1). Moreover, the introduction of HDI has been demonstrated to not impact their superior intrinsic flame retardance, despite an observed reduction in the residual char yields in the HDI-modified groups. Given these excellent properties, PBz-HDI aerogels are expected to be promising candidates for thermal insulation and fire resistance applications. [ABSTRACT FROM AUTHOR]