A facile approach to prepare cage‐ladder‐structure phosphorus‐containing amino‐functionalized POSS for enhancing flame retardancy of epoxy resins

Abstract

The cage-ladder-structure phosphorus-containing amino-functionalized polyhedral oligomeric silsesquinoxanes (CLNH 2-POSS) have been synthesized through a facile catalyst-free hydrolytic condensation of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-vinyltrimethoxysilane (DOPO-VTMS) with 3-aminopropyl trimethoxysilane (KH540). The successful preparation of CLNH 2-POSS has been proven by the characterization of Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy (1 H-NMR, 29 Si-NMR), matrix-assisted laser desorption ionization time of flight (MALDI-TOF), and X-ray diffraction (XRD). Then flame retardant (FR) epoxy resins (EPs) were prepared by the addition of different content of CLNH 2-POSS into EPs with thermal curing technology. The CLNH 2-POSS showed good solubility in EP matrix. The well-dispersed CLNH 2-POSS contributed to thermal, mechanical, and FR properties of EP. Dynamic scanning calorimetry nonisothermal curing scans showed that CLNH 2-POSS had accelerating effect on the curing of EP. With the addition of only 3 wt% CLNH 2-POSS (0.30% phosphorus loading), the limiting oxygen index value of the EP composite increased from 25.5 of pure EP to 31.8, and vertical burning (UL-94) V-0 ratings was achieved. In addition, the EP composites showed improved thermal and mechanical properties. The investigations on char residue and pyrolysis volatiles of cured EP further revealed that CLNH 2-POSS exerted FR effects in condensed and gas phase simultaneously.

Synergistic effects of a half‐cage and cage structure phosphorus and nitrogen‐containing POSS with tetrabutyl titanate on flame retardancy of vinyl epoxy resins

“…The absorption bands at 1000–1200 cm −1 are assigned to the stretching vibration of Si‐O‐Si groups. In particular, the absorption band at 1118 cm −1 was assigned to the symmetrical cage structure (cage/open cage), indicating that P/N‐POSS had the characteristics of the cage and half‐cage structure 49,50 …”

“…In particular, the absorption band at 1118 cm À1 was assigned to the symmetrical cage structure (cage/open cage), indicating that P/N-POSS had the characteristics of the cage and half-cage structure. 49,50 The 1 H-NMR spectra of DOPO, KH550 and P/N-POSS are shown in Figure 2. It can be seen that the signals of P H at 8.9 ppm in DOPO and NH 2 at 1.5-1.6 ppm in 18,51 respectively, the integral area for these proton peaks accords well with the theoretical value for protons of P/N-POSS.…”

Mechanical, Thermal Stability, and Flame Retarding Properties of Phosphorus-Modified PET Blended with DOPO-POSS

“…Compared with PET, the T 5% of FRPET decreases, indicating that CEPPA promotes the degradation of PET, while as the temperature increases, phosphorus-containing flame retardants exert a flame retarding effect. After dehydration, a carbon layer is formed on the surface of PET. , It is manifested as the decrease of maximum thermal weight loss rate ( R max ) and the increasing amount of residual carbon to 18.16%. Compared with FRPET, the thermal decomposition temperature T 5% of the DOPO-POSS/FRPET composite has no obvious change, which shows that the addition of DOPO-POSS does not affect the thermal stability at the beginning of heating.…”

Effect of polyhedral oligomeric silsesquioxanes with different structures on dielectric and mechanical properties of epoxy resin

“…The diffraction peak at 21.1° was attributed to the size of SiOSi structure in the core, and the peak at 5.6° was attributed to the distance between DOPOPOSS molecules. [ 24–26 ] Two peaks of EPOSS with lower intensity appear at 6.8° and 19.4°, corresponding to interplanar spacings of ~ 1.33 and ~ 0.47 nm, respectively. The diffraction peak at 19.4° corresponded to the size of SiOSi in the core.…”