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

This work synthesizes a new bifunctional furan derivative (PDMS-FBZ) through a sequence of hydrosilylation of nadic anhydride (ND) with polydimethylsiloxane (PDMS), reaction of the product with p-aminophenol to form PDMS-ND-OH, and its subsequent Mannich reaction with furfurylamine and CH2O. Then, the main chain-type copolymer PDMS-DABZ-DDSQ is prepared through a Diels-Alder (DA) cycloaddition of PDMS-FBZ with the bismaleimide-functionalized double-decker silsesquioxane derivative DDSQ-BMI. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy confirm the structure of this PDMS-DABZ-DDSQ copolymer; differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) reveal it to have high flexibility and high thermal stability (T-g = 177 degrees C; T-d10 = 441 ?; char yield = 60.1 wt%); contact angle measurements reveal a low surface free energy (18.18 mJ m(-2)) after thermal ring-opening polymerization, because the inorganic PDMS and DDSQ units are dispersed well, as revealed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). This PDMS-DABZ-DDSQ copolymer possesses reversible properties arising from the DA and retro-DA reactions, suggesting its possible application as a functional high-performance material.

Automated summary

This work synthesizes a new bifunctional furan derivative (PDMS-FBZ) and prepares a main chain-type copolymer PDMS-DABZ-DDSQ through a Diels-Alder cycloaddition. The copolymer shows high flexibility and high thermal stability, and has a low surface free energy due to the well-dispersed inorganic PDMS and DDSQ units.