A novel adamantyl‐based benzoxazine (AD‐Bz) was successfully synthesized with 1,3‐bis(4‐aniline)‐adamantane (AD) derived from 1‐adamantanol and acetanilide through the Friedel–Crafts alkylation reaction. The chemical structure, curing behavior and curing kinetics of AD‐Bz were characterized by Fourier transform infrared spectroscopy, NMR spectroscopy (1H NMR and 13C NMR) and DSC, respectively. The results indicated that the activation energies (Ea) of AD‐Bz were 106.3 kJ mol−1 (Kissinger–Akahira–Sunose method) and 109.5 kJ mol−1 (Ozawa method), which are significantly lower than that of the benzoxazine derived from salicylaldehyde and 4,4′‐diamine diphenylmethane (P‐ddm). Furthermore, the thermal properties, dielectric properties and flammability properties of poly(AD‐Bz) were explored with dynamic mechanical analysis, an Agilent impedance analyzer and TGA. It was found that poly(AD‐Bz) exhibited higher heat‐resistant properties (Tg = 253.4 °C), higher thermal stability (Td,10% = 401 °C) and lower dielectric constant (εr = 3.16, 10 MHz) compared with poly(P‐ddm), favoring its application as a candidate for interlayer materials in ultra‐large‐scale integrated circuit and aerospace materials. © 2022 Society of Industrial Chemistry.

Cyanate resins are high‐performance thermosetting resins with excellent mechanical, thermal, and dielectric properties. In this work, a novel cyanate ester monomer, 3,9‐bis‐(4‐cyanato‐phenyl)‐2,4,8,10‐tetraoxa‐spiro[5.5]undecane structure (DBCE), is prepared based on a diphenol (DB) with a degradable diacetal structure. The characterization of the chemical structures and polymerization behaviors of the samples are achieved by nuclear magnetic resonance spectroscopy, fourier transform infrared spectroscopy, and differential scanning calorimetry. The obtained results confirm the successful syntheses of DB and DBCE, and the polymerization temperature of DBCE is between 160 °C to 250 °C, which is lower than that of a comparative commercial cyanate ester resin (BADCy). The thermal and dielectric properties of the curedresin (Poly‐DBCE) are explored by dynamic mechanical analysis, thermogravimetric analysis, and an Agilent impedance analyzer. The results reveal that Poly‐DBCE manifest promising heat resistance (Tg = 294 °C) and thermal stability (Td,5 = 347 °C and char yield at 800 °C = 37.6%). The dielectric constant and dielectric loss of the Poly‐DBCE at 10 MHz are 3.11 and 0.0095, respectively. Additionally, the Poly‐DBCE is completely degraded under mildly acidic conditions, and efficient recoveries of carbon fiber and glass fiber with high values are reported from their corresponding fiber‐reinforced composites.