A novel vinylpyridine-based phthalonitrile monomer, namely 2,6-bis[4-(3,4-dicyanophenoxy)styryl]pyridine (BCSP), was synthesized from 2,6-bis(4-hydroxystyryl)pyridine (BHSP) via a nucleophilic displacement of a cyano-substituent with 4-nitrophthalonitrile (NPN). The phthalonitrile resin was cured with 4-(aminophenoxy)phthalonitrile (APPH), and its curing behaviour was investigated by differential scanning calorimetry (DSC), exhibiting a low melting point of 92 °C and an outstanding processing window of about 146 °C. The chemical structures of the BCSP monomer and polymers were characterized by Fourier Transform Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance spectroscopy (NMR). Different post curing temperatures and times resulted in polymers with different crosslinking levels and subsequently influenced the performance of the resins. The prepared BCSP polymer showed a high storage modulus (2.9 GPa–1.8 GPa) between 30 and 400 °C, a high glass transition temperature (T_g > 400 °C), and excellent thermal and thermo-oxidative stabilities with weight retention of 95% at 524.2 °C along with low water uptake.

A monomer of fluorinated phthalonitrile, namely 4,4′-bis(p-perfluoro-phenol-(bis(p-phenol)propane-2,2-diyl)-p-oxy-diphthalonitrile) (PBDP), was synthesized by the nucleophilic substitution reaction of bisphenol A, decafluorobiphenyl and 4-nitrophthalonitrile. The structure of the monomer was characterized by nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The results indicated that the PBDP monomer was synthesized successfully. The monomer was cured in the presence of 4-(aminophenoxy)phthalonitrile (APPH) and the curing behaviour was investigated by differential scanning calorimetry (DSC), suggesting a low melting point of 96 °C and an excellent processing window (96–262 °C). Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) showed that the fluorinated phthalonitrile resin possessed outstanding thermal and thermo-oxidative stabilities as well as good mechanical properties. The glass transition temperature was >400 °C and the 5% thermal degradation temperature was 501 °C. When the frequency was 50 MHz, the dielectric constant and dielectric loss of the polymer were 2.84 and 0.007, respectively. The PBDP resin has ultra-low water absorption of 0.77% and 1.4%, when exposed to an aqueous environment for 50 days at 24 °C and for 24 h at 100 °C, respectively. The prepared PBDP resin with outstanding thermal stability and low dielectric constant is an ideal candidate for aerospace industries, and microelectronic and other electronic packaging materials.