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Synthesis, Characterization, and High Temperature Stability of Si(B)CN ‐Coated Carbon Nanotubes Using a Boron‐Modified Poly(ureamethylvinyl)Silazane Chemistry
Author(s) -
Bhandavat Romil,
Singh Gurpreet
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05079.x
Subject(s) - carbon nanotube , thermogravimetric analysis , materials science , thermal stability , chemical engineering , boron , nanotube , fourier transform infrared spectroscopy , x ray photoelectron spectroscopy , polymer , transmission electron microscopy , amorphous solid , ceramic , polymer chemistry , nanotechnology , chemistry , crystallography , organic chemistry , composite material , engineering
Carbon nanotubes ( CNT ) and polymer‐derived ceramics ( PDC s) are of interest due to their unique multifunctional properties. CNT s, however, tend to lose their well‐defined structure and geometry at about 400°C in air. PDC s 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 R aman spectroscopy and transmission electron microscopy revealed high temperature stability of the carbon nanotube core in flowing air up to 1000°C.