The research presented here is the first report of fabricating multi-walled carbon nanotube (MWCNT) based thin coatings on polyurethane foam (PUF) using Layer-by-Layer assembly, and using MWCNTs to reduce the flammability of PUF. The (440.6 ± 47.1) nm thick four trilayer coatings of polyacrylic acid (anionic layer), polyethyleneimine functionalized MWCNTs (MWCNT-PEI, cationic layer), and polyethyleneimine (cationic layer) contained (50.3 ± 0.1) mass fraction % MWCNT. These thin film coatings completely and uniformly coated all the internal and external surfaces of the PUF. Other then very sparsely populated micron sized aggregates of MWCNT, the surfaces appeared smooth at low magnifications in the Scanning Electron Microscope (SEM). A sea of well dispersed and distributed MWCNTs completely embedded in the coating matrix was observed at high magnifications in the SEM. The thin MWCNT coatings significantly reduced the flammability of PUF; i.e., 68% ± 3% reduction in peak heat release rate and 21% ± 3% reduction in total burn time. This reduction is comparable to what has been achieved with carbon nanofiber (CNF) coated PUF (using LbL) and 50% better than reported for CNF embedded directly into the PUF. Critical to successfully fabricating high quality MWCNT coatings using LbL, retaining MWCNT during the coating process, and significantly reducing the flammability of PUF was first functionalizing the MWCNTs using one of the coating polymers, PEI.
Citation: Chemistry of Materials
Pub Type: Journals
Layer-By-Layer assembly, thin films, multi-walled carbon nanotubes, polyurethane foam, Cone Calorimetry, flammability, soft furnishings