Preparation and properties of novel low dielectric constant benzoxazole‐based polybenzoxazine

A novel benzoxazine monomer containing a benzoxazole group was synthesized using a nonsolvent method and then named DAROH‐a. The structure of DAROH‐a was confirmed by FTIR, 1H NMR, elemental analysis, and mass spectrometry. The curing reaction activation energy was calculated at 140 kJ/mol. Its corresponding crosslinked polybenzoxazines, poly(DAROH‐a), displayed a higher glass transition temperature at 402 °C, a 9% weight loss at the said temperature, and a high char yield of 42 wt % (800 °C, in nitrogen). Moreover, the dielectric constants of poly(DAROH‐a) were low and changed only slightly at different temperatures. Furthermore, the dielectric constants and dielectric loss of poly(DAROH‐a) at the same frequency barely changed from room temperature to 150 °C. The photophysical properties of poly(DAROH‐a) film were also investigated. Poly(DAROH‐a) showed an absorption peak at 280 nm. The photoluminescent emission spectrum of poly(DAROH‐a) film displayed predominant emission peaks at 521 nm. It might have potential application as high‐performance materials because of its excellent dielectric constants stability and thermal stability under high temperature.