Synthesis, Characterization and Properties of Tert‐Butyl‐Terminated Fluorinated Hyperbranched Benzoxazines

Three hyperbranched benzoxazines were synthesized: two containing fluorine (HB‐HFBAPP and HB‐DAPTF) and one aromatic variant without fluorine (HB‐BAPP). Firstly, the chemical structures of these hyperbranched benzoxazines were characterized using Fourier‐transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance ( 1 H‐NMR). Their curing behaviors were analyzed using differential scanning calorimetry (DSC), and the cured hyperbranched polybenzoxazines were further examined for their thermal, dielectric, and hydrophobic properties through thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), impedance analysis, and contact angle measurements. The findings indicate that the incorporation of fluorine atoms significantly improved the thermal properties and reduced the dielectric constant of polybenzoxazine. Specifically, the dielectric constants for P(HB‐HFBAPP) and P(HB‐DAPTF) were measured as 2.41 and 2.42 at 10 MHz, respectively, with the dielectric losses of both being 0.0016, which are considerably lower than the values for P(HB‐BAPP), which were 2.73 and 0.0036. Additionally, P(HB‐HFBAPP) and P(HB‐DAPTF) demonstrated superior thermal properties, exhibiting glass transition temperatures ( T g ) of 228°C and 223°C, along with residual carbon yields ( CY ) of 46.4% and 48.4% at 800°C, respectively, compared to 38.3% for P(HB‐BAPP). Furthermore, the presence of fluorine atoms enhanced the hydrophobicity and moisture resistance of polybenzoxazine, making it a potential candidate for copper‐clad laminate materials.