Thermal and dielectric properties of "thiol-ene" photocured hybrid composite materials from allyl-terminated benzoxazine and SH-POSS

In the present work, allyl-terminated benzoxazine and thiol-functionalized polyhedral oligomeric silsesquioxane (SH-POSS) were synthesized and their molecular structures were confirmed by Fourier transform infrared, proton nuclear magnetic resonance (NMR), carbon-13 NMR, and silicon-29 NMR spectroscopies. The PBZ hybrid composite materials were developed through photopolymerization (ultraviolet (UV) lamp) reactions of allyl-terminated benzoxazine monomer with different weight percentages of SH-POSS (P₁₀, P₃₀, and P₅₀ wt%), followed by thermal curing. The data obtained from transmission electron microscopy and X-ray diffraction analysis infer the presence of homogeneous morphology of the cured samples. Data obtained from differential scanning calorimetry, thermogravimetric analysis, UV transmittance, dielectric, and contact angle studies indicate that the dual cured P₅₀-PBZ hybrid composite exhibits higher thermal, UV shielding, and hydrophobic behavior and lower value of dielectric constant than those of lower weight percentages of SH-POSS reinforced hybrid composites.