Highly Thermally Stable, Transparent, and Flexible Polybenzoxazine Nanocomposites by Combination of Double-Decker-Shaped Polyhedral Silsesquioxanes and Polydimethylsiloxane

Abstract

In this study a new type of bifunctional phenolic compound based on a double-decker silsesquioxane (DDSQ-BP) was synthesized from phenyltrimethylsilane and then reacted (Mannich condensation) with allylamine and CH 2 O to form a bis-allyl benzoxazine DDSQ derivative (DDSQ-BZ). The structures of these DDSQ derivatives were confirmed using Fourier transform infrared and nuclear magnetic resonance spectroscopy and MALDI-TOF mass spectrometry. Highly thermally stable, transparent, and flexible polybenzoxazine prepolymers were obtained after hydrosilylation of DDSQ-BZ with polydimethylsiloxane (PDMS) as the flexible segment; these materials were characterized using differential scanning calorimetry, thermogravimetric analysis, microtensile testing, and UV−vis spectroscopy. The char yield of DDSQ-BZ-PDMS was 73 wt %, significantly higher than that of a typical polybenzoxazine; in addition, DDSQ-BZ-PDMS displayed high flexibility and transparency after thermal curing.

Highly Efficient Route for the Synthesis of a Novel Generation of Tetraorganofunctional Double‐decker Type of Silsesquioxanes

“…At the same time, chemists are looking for synthetic routes exploiting among others hydrosilylation reaction to obtain novel, functionalized Si-based reagents with a specific structure such as silsesquioxanes. [17][18][19][20][21][22][23][24][25][26][27] While hydrosilylation of olefins with silanes has been widely studied, [3,28] the reports on T 8 silsesquioxanes are limited [5,6,[29][30][31][32][33][34] and for double-decker systems of both closed (D 2 T 8 [4,19,25,[35][36][37] ) and opened (M 4 T 8 [38][39][40][41][42][43] ) structure even more scant. [5] Cage-like derivatives have driven much attention due to specific physicochemical properties (governed by the nature of their silicate rigid core and by the number and type of functional groups attached to it) affecting directions of their broad applications from material chemistry to medicine.…”

Hyperbranched‐polysiloxane‐based hyperbranched polyimide films with low dielectric permittivity and high mechanical and thermal properties

“…The characteristic peak of carboxyl hydrogen at approximate 10 ppm was not observed in the typical 1 H‐NMR spectra (Figures S2–S5), also indicating the successful formation of five‐membered imide rings . Additionally, the absorption band at around 1075 cm −1 in the FTIR spectra becomes broader when incorporating HBPSi into the polyimide backbone, which is due to the stretching of Si─O─Si bonds, confirming that the HBPSi is present in the resulting composite films . The peaks of aromatic carbons at about 128.2 ppm, 131.2 ppm, and 133.8 ppm (wide peaks, belonging to HBPSi) in the 13 C‐NMR spectra of HBPSi HBPI (Figures S7–S9) also indicate that the HBPSi is successfully introduced into the resulting hybrid films .…”

Silsesquioxane‐Containing Hybrid Nanomaterials: Fascinating Platforms for Advanced Applications

“…After the incorporation of phenyl‐containing double‐decker SSQs, the thermal decomposition temperature of the (Polybenzoxazine) PBZ/SSQ nanocomposites was observed at 500 °C, which is the highest thermal stability ever reported for membranes. The improved thermal and mechanical properties were attributed to covalent bonding between the rigid SSQ structure and benzoxazine matrix . Octaphenyl‐POSS(Ph‐POSS) was utilized in a hybrid with resorcinol formaldehyde (RF) to form a resol‐type Ph‐POSS/RF ablative heat shielding material for a thermal protection system.…”