New benzoxazines containing polyhedral oligomeric silsesquioxane from eugenol, guaiacol and vanillin

Abstract

Polybenzoxazine–tethered polyhedral oligomeric silsesquioxane nanocomposites with well-defined architectures were prepared by the reaction of bio-phenols: eugenol, guaiacol, vanillin with POSS-octaamine and paraformaldehyde. FT-IR measurements evidenced the occurrence of a Mannich reaction between phenolic groups of bio-phenols and amino groups of POSS molecules, with the consequent formation of a heterocyclic benzoxazine ring binding POSS in its backbone. Their chemical structures were confirmed using ¹H and ¹³C-NMR analysis. The thermo-mechanical properties and thermal stability of the POSS–polybenzoxazine hybrid networks were determined using DSC, DMA and TGA. SEM, EDX, AFM and TEM micrographs show that POSS–Pbz nanocomposites exhibit featureless morphologies with no discernible phase separation, suggesting that the POSS nanoparticles are dispersed homogeneously throughout the matrix. The homogeneity of these networks with octafunctional POSS is also indicated by their moduli in the range of 2.63 to 2.91 GPa. Moreover, their dielectric values [both dielectric constant (1.85) and dielectric loss (0.28)] and moisture absorption values are very low (<0.01%), which makes them suitable materials for use in microelectronics packaging.