Thermostable cyanate ester resins and POSS-containing nanocomposites: influence of matrix chemical structure on their properties

Thermostable densely crosslinked cyanate ester resins (CER) with different chemical structures, derived from monomer dicyanate esters of bisphenol E (DCBE), bisphenol A (DCBA), hexafluorobisphenol A (6F-DCBA) or from cyanated phenol-formaldehyde oligomer PT-30, and the nanocomposites based thereon, with 0.01 to 10 wt% epoxycyclohexyl-functionalized polyhedral oligomeric silsesquioxane (ECH-POSS), were synthesized and characterized by means of dynamic mechanical analysis, differential scanning calorimetry, far-infrared, and creep rate spectroscopy techniques. As shown, thermal and mechanical properties increased in a row of matrices prepared from DCBE < DCBA < 6F-DCBA < PT-30. Thus, these matrices with T_g = 248, 275, 300, and ~400°C (DMA, 1 Hz), respectively, had dynamic modulus E′ values of 1.8, 2.7–3.0, and 3.6 GPa at 20°C; high rigidity (dynamic modulus of about 1–2 GPa) retained at temperatures up to 200°C for DCBE matrix, 250°C for DCBA and 6F-DCBA matrices, but up to 380°C for PT-30-based matrix. The maximal effects from introducing ECH-POSS nanoparticles, covalently embedded into CER network, were attained mainly at their ultra-low contents (<<1 wt%); however, the ECH-POSS impact decreases in a row of matrices prepared from DCBE > DCBA > 6F-DCBA > PT-30. Copyright © 2015 John Wiley & Sons, Ltd.