Competitive Study of Novel Triptycene-Containing Benzoxazine Monomers and a Thermoresponsive Linear Main Chain-Type Benzoxazine Copolymer: Synthesis, Polymerization, and Thermal Properties of Their Thermosets

Abstract

Two novel triptycene-based dioxazine benzoxazine monomers (TB-a and TB-fa) have been synthesized using triptycene-1,4-hydroquinone (TB), aniline/furfurylamine, and paraformaldehyde as raw materials. The chemical structures of both dioxazine benzoxazine monomers were elucidated by 1 H and 13 C NMR, Fourier transform infrared (FT-IR), high-resolution mass spectroscopy, and elemental analysis. By taking advantage of the furan groups present in TB-fa and the reversibility of the Diels−Alder reaction, 4,4′-bismaleimidodiphenylmethane (DDM-BMI) was used as a comonomer for synthesizing a thermoresponsive linear main chain-type benzoxazine copolymer (TB-fa-co-DDM-BMI). The polymerization processes of oxazine ring-containing monomers and the copolymer were studied by DSC and in situ FT-IR analyses, while the thermal stability and flammability of the resulting thermosets were studied by thermogravimetric analysis and microscale combustion calorimetry. Remarkably, the thermoset derived from the thermoresponsive TB-fa-co-DDM-BMI exhibits the best thermal stability as demonstrated by the T d10 and Yc values of 388 °C and 55% at 800 °C under a nitrogen atmosphere, respectively. Its low heat release capacity value of 31.9 J g −1 K −1 shows its great potential as a good flame retardant agent. The outstanding properties exhibited by the herein presented polybenzoxazines, compared to those of many other reported traditional polybenzoxazines, evidence their potential applications in the design of advanced materials.

Design of a Low-Temperature Ring-Opening Benzoxazine System Using a Supramolecular Hydrogen-Bond Structure

“…Benzoxazine resin is an ideal substitute for traditional epoxy and phenolic resins, benefiting from its excellent comprehensive performance. 1,2 Only by molecular engineering, the stateof-the-art polybenzoxazine resins have enabled sustainable preparation, 3−5 topological designation, 6 templated carbonization, 7 extreme-environment protection, 8−10 and multifunctional integration. 11,12 However, their excellent properties are usually accompanied by relatively high processing temperatures.…”

Fracture Behavior of Polybenzoxazine Toughened by Polyrotaxane Molecules and Core–Shell Rubber

“…Polybenzoxazine (PBa) is a phenolic-based thermoset resin with excellent thermo-oxidative stability and dielectric properties compared to epoxies due to their abundant hydrogen bonding (H-bonding) sites combined with crosslinked structures. − In addition, several features of PBa, including noncatalyst polymerization, near-zero cure shrinkage, low water absorption, good flame retardancy, and rich molecular design flexibility, make it attractive for a wide variety of applications. − However, PBa is intrinsically brittle due to its rigid and crosslinked structure, which limits its applications in the microelectronic and aerospace fields. , …”

“…For intrinsically brittle PBa, common routes for toughening are by incorporation of large amounts of thermoplastic phase, hybrid particles, or reactive rubber particles. Although the incorporation of a ductile second phase can dissipate energy and improve fracture toughness, it normally couples with a deterioration of the thermomechanical properties of the thermoset matrix. ,− A hybrid toughening strategy utilizing both rigid reinforcing phases and soft core–shell rubber (CSR) has been shown to simultaneously improve fracture toughness and Young’s modulus of thermoset resins without influencing glass transition temperature ( T g ). ,, Most recently, Zhu et al prepared well-dispersed multiwalled carbon nanotube (MWCNT) and CSR in epoxy to enhance epoxy tensile properties and fracture toughness while maintaining high T g . The observed synergistic toughening effect is attributed to crack deflection, fracture of MWCNT, along with the cavitation of rubber-induced matrix shear banding.…”

“…21,23,24 Most recently, Zhu et al prepared well-dispersed multiwalled carbon nanotube (MWCNT) and CSR in epoxy to enhance epoxy tensile properties and fracture toughness while maintaining high T g . 16 The observed synergistic toughening effect is attributed to crack deflection, fracture of MWCNT, along with the cavitation of rubber-induced matrix shear banding. In another example, Liu, et al utilized exfoliated α-zirconium phosphate (ZrP) nanoplatelets with CSR to toughen epoxy resins.…”

Novel Latent Catalyst for Ring-Opening Polymerization of 1,3-Benzoxazines Triggered by a Dual Ionic/Non-ionic Monomer Partnership

“…15,16 The application of polybenzoxazines in various fields of the industry is incontestable and still requires further attention. Among other wellknown applications, recently polybenzoxazines can find many unconventional applications in cutting-edge technologies, such as chelation agents for metal recovery, 17,18 high-performance composites, 19,20 space radiation insulating shields, porous materials for CO 2 capture, 21−23 anticorrosion coatings, 24−28 or even self-healing and shape-memory polymers. 29−32 Polybenzoxazines are obtained by thermally accelerated ringopening polymerization of 1,3-benzoxazine, and the exothermic peak temperature corresponding to this process is in the temperature range 160−250 °C, decisively depending on monomer structure and the number of oxazine rings in developments concerning designing of new monomers motives.…”