(688f) The Design of Advanced Non-Toxic Flame Retardants Based on DNA and DNA Functionalized Single-Walled Carbon Nanotubes

Reduced flammability (high combustion burning temperature and low burning rate) is a desirable feature of novel advanced materials. Synthetic moieties added to consumer products to meet federal and state flammability standards have been reported to show up in waterways, wildlife and even human breast milk. Studies in laboratory animals and humans have linked the most conventional flame retardants, called polybrominated diphenyl ethers, or PBDEs, to thyroid disruption, memory and learning problems, and reduced fertility.

Due to their intrinsically high Young’s modulus and thermal conductivity, carbon nanomaterials have been incorporated into composites yielding nanocomposites with unique mechanical and thermal properties. The flammabilities of nanocomposites containing single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) have been effectively decreased compared to controls and to those containing carbon black powder. Additionally, single-stranded DNA (ssDNA) has been proven as an intrinsically intumescent flame retardant due to the production of thermally-insulating char upon combustion. Therefore, SWCNTs individually dispersed with ssDNA (ssDNA-SWCNT) have a great potential to be effectively incorporated into polymer composites to enhance their thermal and mechanical properties.

Herein, using thermogravimetric analysis (TGA), we examined the burning temperature and burning rate of ssDNA functionalized carbon nanomaterials. We find that ssDNA increases the burning temperature of HiPco SWCNTs by 223 °C. We also find that ssDNA increases the burning temperature of other carbon nanomaterials such as MWCNTs, Reduced Graphene Oxide (RGO), and Fullerene (C60). We further find that the burning rate (another burning characteristic which determines how fast the material burns when the temperature is reached to the burning temperature of the material) can be controlled by manipulating the sequence of the DNA used in the construction of the hybrids. Finally, we demonstrate that ssDNA-SWCNT hybrids incorporated into a simple polymer composite of poly (vinyl alcohol) increased the burning temperature of the composite by 45 °C.