NANOCOMPOSITES BASED ON A HEAT RESISTANT POLYCYANURATE MATRIX

The review article is devoted to a promising and rapidly developing class of thermosetting polymers – polycyanurates created from cyanate ester resins (CER), in particular, to the synthesis and characterization of the structure and physical properties of their nanocomposites obtained by in situ method using inorganic nanoparticles with an organo-functionalized surface. Cyanate ester resins are very easy to use, and the technology of their processing is close to the technology of manufacturing materials based on traditional epoxy resins. Due to their high heat resistance, cyanate ester resins are increasingly replacing epoxy materials, especially in high-tech industries. An important feature of the synthesis of nanocomposites based on polycyanurates is that almost all functionalized nanoparticles used in the published studies catalyze the high-temperature polycyclotrimerization of dicyanates into polycyanurates. Nanoparticles with reactive groups on a surface, such as hydroxy, phenolic, amine, epoxy, etc. are covalently embedded in the forming polymer network during the synthesis process due to their easy chemical interaction with cyanate groups of the cyanate ester resin. The chemical reactions to such hybridization have been thoroughly studied. This phenomenon prevents an aggregation of nanoparticles and leads to their effective distribution in a polymer matrix, which in turn ensures high performance of the resulting nanocomposites. A specific effect of ultra-low (<1 wt.%) nanofiller concentrations on the glass transition temperature, heat resistance and mechanical strength of the resulting nanocomposites has been established: the glass transition temperature of polycyanurate increases by 40–60 °C with the introduction of 0.01 to 1.00 wt.% of epoxy-functionalized polyhedral oligomeric silsesquioxane (POSS), amino-SiO2, amino-POSS or amino-functionalized montmorillonite (MMT). Increasing the content of nanoparticles above ~2 wt.% usually leads to the opposite effect due to the formation of their aggregates. The areas of industrial application of nanocomposites based on polycyanurates are described. It has been shown that the valuable complex of thermal, dielectric, mechanical, and chemical properties of polycyanurates, as well as their ability for nanostructuring and all kinds of chemical modifications, due to the high reactivity of the cyanate groups of CER, contribute to the wide application of CER, polycyanurates and nanocomposites based on them in various fields of industry instead of traditional epoxy resins. In recent years, the use of CER, its composites and nanocomposites has increased significantly in the aerospace and defense industries, in the manufacture of electrical products and electronics, etc. CER-based products are used as potting resins, binders for carbon, glass and organic plastics, coatings, adhesives in aircraft, helicopters, satellites, antennas, gas turbines, microchips, etc.