High Thermal Resistance of Epoxy/Cyanate Ester Hybrids Incorporating an Inorganic Double-Decker-Shaped Polyhedral Silsesquioxane Nanomaterial

Abstract

In this study, we prepared a difunctionalized cyanate ester double-decker silsesquioxane (DDSQ-OCN) cage with a char yield and thermal decomposition temperature (Td) which were both much higher than those of a typical bisphenol A dicyanate ester (BADCy, without the DDSQ cage) after thermal polymerization. Here, the inorganic DDSQ nanomaterial improved the thermal behavior through a nano-reinforcement effect. Blending the inorganic DDSQ-OCN cage into the epoxy resin improved its thermal and mechanical stabilities after the ring-opening polymerization of the epoxy units during thermal polymerization. The enhancement in the physical properties arose from the copolymerization of the epoxy and OCN units to form the organic/inorganic covalently bonded network structure, as well as the hydrogen bonding of the OH groups of the epoxy with the SiOSi moieties of the DDSQ units. For example, the epoxy/DDSQ-OCN = 1/1 hybrid, prepared without Cu(II)-acac as a catalyst, exhibited a glass transition temperature, thermal decomposition temperature (Td), and char yield (166 °C, 427 °C, and 51.0 wt%, respectively) that were significantly higher than those obtained when applying typical organic curing agents in the epoxy resin. The addition of Cu(II)-acac into the epoxy/BADCy and epoxy/DDSQ-OCN hybrids decreased the thermal stability (as characterized by the values of Td and the char yields) because the crosslinking density and post-hardening also decreased during thermal polymerization; nevertheless, it accelerated the thermal polymerization to a lower curing peak temperature, which is potentially useful for real applications as epoxy molding compounds.

Construction of Fluorescent Conjugated Polytriazole Containing Double-Decker Silsesquioxane: Click Polymerization and Thermal Stability

“…Thus, the mono-, di-, or multi-functional POSS cage structures were synthesized using a covalent bond connected to the polymer chain to avoid the macro-phase separation of the POSS cage. Compared with a mono-functional POSS cage as the chain end or side chain into the polymer matrix [ 26 , 27 , 28 , 29 , 30 ], the multi-functional POSS cage would form a network structure that could not dissolve in common solvents, which would restrict the potential applications for future processing [ 31 , 32 , 33 , 34 , 35 ]. As a result, the preparation of di-functional POSS mostly adopts the T 10 type to prepare double-decker silsesquioxanes (DDSQs) into the polymer matrix as the bead-type main chain of polymer/POSS hybrids have also been investigated recently [ 36 , 37 , 38 , 39 , 40 ].…”

Thermal Stable and Flexible Bio‐Based Polybenzoxazine with Epoxy‐Functionalized Poly(dimethylsiloxane) Hybrids

“…[24][25][26][27][28] However, conventional epoxy resins are unable to meet the requirements for thermal or flame resistance. In order to address this limitation, high thermal stability polymers such as benzoxazine, [23,29] bismaleimides, [30,31] cyanate esters, [32,33] and polyethersulfone [34] are often incorporated into epoxy resins to escalate their properties.…”