Double-Decker-Shaped Polyhedral Silsesquioxanes Reinforced Epoxy/Bismaleimide Hybrids Featuring High Thermal Stability

Abstract

In this study, we synthesized bismaleimide into a functionalized double-decker silsesquioxane (DDSQ) cage. This was achieved by hydrosilylation of DDSQ with nadic anhydride (ND), reacting it with excess p-phenylenediamine to obtain DDSQ-ND-NH2, and treating with maleic anhydride (MA), which finally created a DDSQ-BMI cage structure. We observed that the thermal decomposition temperature (Td) and char yield were both increased upon increasing the thermal polymerization temperature, and that these two values were both significantly higher than pure BMI without the DDSQ cage structure since the inorganic DDSQ nanoparticle could strongly enhance the thermal stability based on the nano-reinforcement effect. Based on FTIR, TGA, and DMA analyses, it was found that blending epoxy resin with the DDSQ-BMI cage to form epoxy/DDSQ-BMI hybrids could also enhance the thermal and mechanical properties of epoxy resin due to the organic/inorganic network formation created by the ring-opening polymerization of the epoxy group and the addition polymerization of the BMI group due to the combination of the inorganic DDSQ cage structure and hydrogen bonding effect. The epoxy/DDSQ-BMI = 1/1 hybrid system displayed high Tg value (188 °C), Td value (397 °C), and char yield (40.4 wt%), which was much higher than that of the typical DGEBA type epoxy resin with various organic curing agents.

Highly Thermally Stable, Reversible, and Flexible Main Chain Type Benzoxazine Hybrid Incorporating Both Polydimethylsiloxane and Double‐Decker Shaped Polyhedral Silsesquioxane Units through Diels–Alder Reaction

“…As mentioned above, the uncured PDMS‐FBZ underwent thermal ROP at 235 °C, with a broad exothermic peak (289 °C) observed in Figure 3c corresponding to the addition–polymerization of pure DDSQ‐BMI. [ 40 ] The broad maximum exothermic peak of the PDMS‐DABZ‐DDSQ copolymer appeared at 230 °C, slightly lower than that of PDMS‐FBZ, due to thermal cross‐linking polymerization. Furthermore, a broad complex endothermic signal appeared near 135 °C, corresponding to the retro‐DA reaction; thus, cleavage of the DA cycloaddition products, induced through a thermoresponsive reaction, presumably generated new polymerizable and reactive functional units (e.g., maleimide and furan units).…”

“…[9] Attempts have been made to decrease chain mobility of BZ resin to improve its thermal and mechanical properties by incorporating unsaturated (such as allyl or alkynyl) groups, blending with high-performance polymers to form miscible blends, [10][11][12][13][14][15][16] and adding inorganic nanoparticles. [17][18][19][20][21][22] Many organic/inorganic polybenzoxazine (PBZ) hybrids (and other thermosetting resins) have been prepared by incorporating carbon-based materials (e.g., carbon nanotubes, [23][24][25] carbon black, [26] and graphene [27][28][29][30] ) and siliconbased materials [e.g., polydimethylsiloxane (PDMS), [5,[31][32][33] organic modified clay, [34,35] and polyhedral oligomeric silsesquioxane (POSS) [17][18][19][20][21][22][36][37][38][39][40] ]. For example, polymer/POSS hybrids have been obtained from mono-and multifunctionalized POSS derivatives through blending or copolymerization, initially forming organic/inorganic hybrids with only relatively lowmolecular-weight or insoluble cross-linked structures.…”

“…Many organic/inorganic polybenzoxazine (PBZ) hybrids (and other thermosetting resins) have been prepared by incorporating carbon‐based materials (e.g., carbon nanotubes, [ 23–25 ] carbon black, [ 26 ] and graphene [ 27–30 ] ) and silicon‐based materials [e.g., polydimethylsiloxane (PDMS), [ 5,31–33 ] organic modified clay, [ 34,35 ] and polyhedral oligomeric silsesquioxane (POSS) [ 17–22,36–40 ] ]. For example, polymer/POSS hybrids have been obtained from mono‐ and multifunctionalized POSS derivatives through blending or copolymerization, initially forming organic/inorganic hybrids with only relatively low‐molecular‐weight or insoluble cross‐linked structures.…”

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

“…The polyhedron structures include complete cage and partial cage structures [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Polyhedral oligomeric silsesquioxane (POSS) as an inorganic cage structure in the polymer matrix could improve the thermal, mechanical, surface, and dielectric properties that have been widely investigated during the last two decades [ 21 , 22 , 23 , 24 , 25 ] because of its high molecular weight and three-dimensional structure that could reduce the possibility of molecular stacking and even crystallization. Our previous studies have proposed the polymer matrix’s non-functional, mono-functional, di-functional, and multi-functional POSS cage structures [ 15 ].…”

Synthesis of a Novel Bifunctional Epoxy Double-Decker Silsesquioxane: Improvement of the Thermal Stability and Dielectric Properties of Polybenzoxazine

“…In most cases, the monofunctionalized POSS is located at the polymer chain end or side chain and multifunctional POSS nanoparticles added to the polymer matrix typically produces insoluble cross-linked polymers. It is worth nothing that the addition of a low content of bifunctional POSS to the polymer can generally form polymer/POSS nanocomposites with the POSS unit in the main chain [ 41 , 42 , 43 , 44 , 45 ]. The use of bifunctional POSS for thermoset plastic provides new approaches for the development of novel polymer/POSS nanocomposites.…”