Single/multi-walled carbon nanotubes (MWCNTs) have many desirable properties such as high thermal conductivity, mechanical strength, and optical properties. However, these nanotubes tend to lose their structure and geometry due to oxidation at around 400 degrees Celsius in air. On the other hand, polymer-derived ceramics (PDC) are featureless in X-ray and TEM yet possess high oxidation resistance, high temperature piezoresistivity, high mechanical strength, and photoluminescence. Also, since the PDC precursor is a polyureasilazane polymer in liquid state, it allows the final ceramic to take any desired shape upon curing. Considering the above properties, it was devised to combine both materials to develop a polymer-derived ceramic-multiwall carbon nanotube composite (PDC-MWCNT). Additionally, it was determined that there was a need to improve the thermal stability of existing PDC-MWCNTs, as current processes for this achievement are difficult, time-consuming, and require the use of corrosive chemicals.
With the above limitations and opportunities in mind researchers at Kansas State University have developed a single-step process for making boron-modified silazanes which upon being heated in nitrogen yield thermal-resistive Si-B-C-N ceramics. This process can be carried out at atmospheric conditions and the resulting nanocomposites are resistant to oxidation in flowing air at up to at least 1000 degrees C. In another embodiment, these nanocomposites are combined with a range of nanofillers such as CNTs, graphene nanoparticles and carbon fiber, thus resulting in PDC-composites that can be used in a range of significant applications such as a self-standing lithium ion battery anode.
ADVANTAGES AND TECHNICAL MERITS:
-PDC remains predominantly amorphous with no crystallization at up to 1500 °C, while the PDC composites exhibit thermal stability at up to 1000 °C in flowing air. PDC exhibits resistance to laser irradiation up to 15kWcm-2 at a wavelength of 10.6µm for 10 seconds.
-In Li-ion battery applications, reversible capacity of this PDC-CNT composite is observed to be 412.1 mAh/g after 30 cycles.
-Process is easy, does not require an exclusive experimental setup for boron doping, and can be performed at atmospheric pressure.
-Process does not involve use of corrosive chemicals, nor produces any by-products; hence avoiding additional steps of elimination
APPLICATIONS AND COMMERCIAL OPPORTUNITIES:
-Preparation of strong and high temperature-resistant nanocomposites, particularly carbon nanotube composites such as PDC-MWCNTs.
-Nanocoatings or spray paint for materials that require protection in extreme environments such as rocket nozzles, laser thermal detectors and steam turbine blades.
-PDC composite with CNT or graphene filler material as a self-sustaining negative electrode for Lithium-ion rechargeable batteries
-International Patent Protection (#14/377,123) filed in USA on August 6, 2014