Dynamics and properties of high performance amorphous Cyanate Ester-based subnanocomposites with ultralow silica content and quasi-regular structure

We have fabricated amorphous polymer composites with ultralow silica contents (e.g., 0.1 wt %), without nano- or microclusters but with silica units distributed quasi-regularly within the polymer network matrix. This fact and other data obtained imply the existence of subnanometer-sized silica nodes (SNSSN) only in this case which are connected covalently with the matrix, i.e., the formation of the hybrid subnanocomposites. In this work, the densely cross-linked Cyanate Ester Resins (CER)-based composites with 0.1–10 wt % silica, introduced by a sol-gel method, were synthesized and investigated by HAADF STEM, EDXS, far-IR spectroscopy, DMA and DSC. The obtained subnanocomposites manifest an extremely high “constrained dynamics” effect and superiority in thermal and mechanical properties compared to those of the nanocomposites with higher silica contents. [Display omitted] •Subnanostructures may be formed in densely cross-linked CER-Silica hybrid networks with silica contents ≪1 wt %.•At ultralow silica contents, subnano-sized silica nodes are distributed quasi-regularly in the amorphous matrix nanovolumes.•Extremely high “constrained dynamics” effect is attained in the CER-Silica subnanocomposites.•Superiority in thermal/mechanical properties of these subnanocomposites compared to those of the nanocomposites is shown.