Easily Processable Thermosets with Outstanding Performance via Smart Twisted Small‐Molecule Benzoxazines

Abstract

High‐performance aromatic polymers have excellent thermal, mechanical, and electrical properties and are lightweight, but it is highly challenging to deliver outstanding performances while still maintaining good processability of the precursors. Here, a new family of small‐molecule benzoxazine resins with ortho‐maleimide functionality is reported, which strikes an exceptional balance between the processability and performance. The excellent processability is attributed to the twisted molecular configurations of ortho‐maleimide‐substituted benzoxazines, which prevent intermolecular packing in the resin systems. The new benzoxazines can polymerize through multiple routes, which eliminate the twisted structures and create highly cross‐linked polymer networks. The resulting new polymers are found to possess fascinating properties such as a high thermal stability (no Tg can be detected before 400 °C), excellent flame retardancy (a heat release capacity of 42.5 J g−1 K−1), and low dielectric constants (2.62–2.30 in the frequency range of 1 Hz to 10 MHz). The combined processability and versatility highlight the potential of smart benzoxazines in the preparation of high‐performance thermosets, with important new applications that may span aerospace, transportation, and electronic packaging materials.

Review on the Accelerated and Low-Temperature Polymerization of Benzoxazine Resins: Addition Polymerizable Sustainable Polymers

“…This is accounted to by the formation of highly crosslinked network, stemming from the occurrence of multiple polymerization reactions, namely, oxazine ROP, cyano cyclotrimerization and benzoxazole ring formation [ 199 ]. Benzoxazine monomers with atropisomerism [ 200 , 201 , 202 , 203 ] account for a more interesting set of properties than traditional benzoxazine structures. The formation of highly cross-linked networks through multiple polymerization behaviors in single-component resins is advantageous in terms of ease of processability and high performance properties of ortho -maleimide functional benzoxazines with additional crosslinking such as cyano or acetylene functionalities [ 203 ].…”

Synthesis and Characterization of Low-Cost Cresol-Based Benzoxazine Resins as Potential Binders in Abrasive Composites

“…The superior thermal and mechanical properties of benzoxazine resins have already been confirmed. Ortho-maleimide-substituted benzoxazines exhibit good processability and very high glass transition temperature with great inflammability [ 25 ]. Polybenzoxazines from resveratrol-based tri-functional monomers exhibit a similarly high performance characteristic.…”

Effect of backbone and end-group regioisomerism on thermomechanical properties of vanillin-based polyurethane networks

“…The review by Dusek et al 8 lists monomers with multiple geometric differences, including star-like and hyperbranched molecules with various degrees of freedom and length between functional groups and their effect on material properties. The effect of conformation, regioisomerism, stereoisomerism on physical properties has also been explored in bisphenol, 9,10 benzoxazine, [11][12][13] and azobenzene 14,15 based systems. Others have investigated the effect of changes in ring substitutions on the physical properties of the ensuing network.…”