Design, synthesis, flame retardancy and dielectric properties of novel aromatic hyperbranched benzoxazine

Two kinds of novel aromatic hyperbranched benzoxazines (HBs), HB-Tppal and HB-Tppa2, were designed and prepared by using 1,1,1-tris(4-hydroxyphenyl)ethane (THPE), p-phenylenediamine (PPA), paraformaldehyde and phenol through two different synthetic routes via Mannich condensation reaction. Fourier transform infrared (FTIR) and nuclear magnetic resonance (H-1 and (13) NMR) spectroscopy were employed to characterize the featured structures of these (HB-Tppa)s. HB-Tppal exhibits greater molecular weight than HB-Tppa2, owing to a priority of forming the hyperbranched structure for preparing HB-Tppal without adding capped phenol in the first step. The greater reaction enthalpy (Delta H) value of HB-Tppal has been provided by differential scanning calorimeter (DSC), indicating that the mass fraction of benzoxazine rings in HB-Tppal is higher than that of HB-Tppa2. The thermal and flame retardancy properties of poly(HB-Tppal) superior to poly(HB-Tppa2) are affected by these mentioned factors. Besides the high glass transition temperature (T-g >= 320 degrees C), the low total heat release (THR) and heat release capacity (HRC) values of poly(HB-Tppa)s in the range of 5.4-11.7 kJ/g and 41.5-50.5 J/(g K), respectively, suggest that they are potential nonignitable materials. Moreover, the poly(HB-Tppa)s exhibit low dielectric constants (2.27 >= k >= 2.15) in the high-frequency range of 2 to 18 GHz, which may perform well in next-generation integrated circuits.

Automated summary

Two novel aromatic hyperbranched benzoxazines (HBs) with different structures and properties were designed and prepared. The experimental results showed that one of the polymers, HB-Tppal, exhibited higher molecular weight and better thermal properties, indicating its potential applications.