The impact of ultra-low amounts of introduced reactive POSS nanoparticles on structure, dynamics and properties of densely cross-linked cyanate ester resins

Abstract

Thermostable nanocomposites based on densely cross-linked Cyanate Ester Resins (CER), derived from bisphenol E and doped by 0.01–10wt.% epoxycyclohexyl-functionalized polyhedral oligomeric silsesquioxane (ECH-POSS), were synthesized and characterized in detail by means of TEM, SAXS, EDXS, FTIR, DSC, DMA, TGA, far-IR and creep rate spectroscopy techniques. It was revealed that ultra-low POSS contents (≪1wt.%), covalently embedded into CER network, substantially changed its nanostructure and properties. This resulted in changing network dynamics; increasing glass transition temperatures by 20–50°C; enhancing high temperature elastic and creep resistance properties, and increasing thermal stability under inert atmosphere at T<400°C. The effects being observed decreased, or even became zero or negative, while increasing POSS content, especially from 2 to 10wt.%, due to arising the structural nanorod- or platelet-like formations and POSS-enriched nanodomains. At ultra-low POSS contents, the data obtained suggest basically molecular POSS dispersion, their quasi-periodic spatial distribution in the matrix, and not only chemical modifying CER network but also the possible manifestation of the enhanced long-range action of the “constrained dynamics” effect.