Organic–Inorganic Composites Involving Epoxy and Double Decker Silsesquioxanes With Micro‐ and Nano‐Scale Phase Separation

For organic–inorganic composites of epoxy with polyhedral oligomeric silsesquioxanes (POSS), dispersion of POSS is ‐ pivotal to influence the thermomechanical properties of materials. However, this effect has scarcely been investigated. This work is to unlock the correlation of morphologies with thermal, mechanical, surface, and dielectric properties. Toward this end, we first synthesized two structurally similar double decker silsesquioxanes (DDSQs), which carry two nitrophenyl and aminophenyl groups, respectively. Both of the POSS cages were exploited to gain the organic–inorganic composites with epoxy thermosets. It was found that the nuanced difference in functional groups between these DDSQ macromers led to a significant difference in the morphologies of composites. For the composites containing 3,13‐dinitrophenyl DDSQ, the phase‐separated morphologies on the micrometer scale were exhibited. In contrast, the composites with 3,13‐diaminophenyl DDSQ displayed the phase separation on the nanometer scale. The significant difference in morphologies resulted in the quite different thermal, mechanical, surface, and dielectric properties. The results of this work demonstrate that it is critical to regulate the morphologies for the control over the properties of organic–inorganic composites of epoxy with POSS.