Synthesis, Characterization, and High Temperature Stability of Si(B)CN‐Coated Carbon Nanotubes Using a Boron‐Modified Poly(ureamethylvinyl)Silazane Chemistry

Abstract

Carbon nanotubes (CNT) and polymer‐derived ceramics (PDCs) are of interest due to their unique multifunctional properties. CNTs, however, tend to lose their well‐defined structure and geometry at about 400°C in air. PDCs on the other hand are structureless in X‐ray diffraction but show high chemical and thermal stability in air (up to ~1400°C). Herein, we demonstrate synthesis of a composite nanowire structure consisting of polymer‐derived silicon boron‐carbonitride (Si–B–C–N) shell with a multiwalled carbon nanotube core. This was achieved through a novel process involving preparation of a boron‐modified liquid polymeric precursor through a reaction of trimethyl borate and poly (ureamethylvinyl) silazane under normal conditions; followed by conversion of polymer to ceramic on carbon nanotube surfaces through controlled heating. Chemical structure of the polymer was studied by liquid‐Nuclear Magnetic Resonance (NMR) while evolution of various ceramic phases was studied by solid‐NMR, Fourier transform infrared and X‐ray photoelectron spectroscopy. Electron microscopy and X‐ray diffraction confirm presence of amorphous Si(B)CN coating on individual nanotubes for all specimens processed below 1400°C. Thermogravimetric analysis, followed by Raman spectroscopy and transmission electron microscopy revealed high temperature stability of the carbon nanotube core in flowing air up to 1000°C.

Facile Synthesis and High Rate Capability of Silicon Carbonitride/Boron Nitride Composite with a Sheet-Like Morphology

“…Atomic percentage of boron in the composite was 6.8%, which is much higher than other boron-doped SiCN. 40 The peak at approximately 190.5 eV for high resolution B 1s in Figure 3b confirmed the presence of B-N bond in the pyrolyzed composite, thereby suggesting successful retention of BN after pyrolysis. 40,42 High resolution XPS spectrum of C 1s and N 1s for SiCN and SiCN/BP are included in Supporting Information The chemical bonds present were also characterized using Fourier Transform Infrared (FTIR) spectroscopy which showed that SiCN/BN and SiCN/BNF had strong BN bond vibrations with no obvious presence of B-O bonding (Supporting Information Figure S5).…”

Synthesis of Novel Cobalt-Containing Polysilazane Nanofibers with Fluorescence by Electrospinning

“…The other peaks are due to C–N species at 286.3 eV and Si–C at 283.4. The silicon peaks at 100.4 eV [ 33 , 40 ] and 102.0 eV [ 41 ] corresponding to Si–C and Si–N bonds, respectively. Meanwhile, the N 1s band on deconvolution showed peaks at 396.8 eV and 397.8 eV attributable to Si–N bonds [ 40 ].…”

Polymer-derived ceramics as anode material for rechargeable Li-ion batteries: a review

“…Furthermore, the direct polymer-to-ceramic processing route makes these ceramics suitable for making complex structures at micro and nanometer scales including fi bers, 23,24 thin fi lms 25,26 and shell/core nanocomposites. [27][28][29][30][31] In addition, the polymer-to-ceramic route also allows homogenous distribution of constituent elements at the molecular level with controlled microstructure.…”