Polymeric nanocomposites of polyurethane block copolymers and functionalized multi-walled carbon nanotubes as crosslinkers

We report on a new route to synthesize polymeric carbon nanotube-polyurethane (PU) nanocornposites. Multi-walled carbon nanotubes (MWNTs) functionalized by chemical modification were incorporated as a crosslinker in prepolymer, which was prepared from a reaction of 4,4'methylene bis(phenylisocyanate) and poly (epsilon-caprolactone)diol. The reinforcing effect of carbon nanotubes in crosslinked MWNT-PU nanocomposites was more pronounced as compared to that in conventional MWNT-PU nanocornposites. The Optimum content of chemically modified MWNTs for crossfinking with polyurethane was determined to be approximately 4 wt.-% in our samples, based on observation of a NCO peak in FT-IR spectroscopy. MWNT-crosslinked polyurethane containing 4 wt.-% modified MWNTs showed the highest modulus and tensile strength among the composites and pure PU. The presence of functionalized MWNTs in the polymeric nanocomposite yielded enhancement in the thermal stability due to crosslinking of the MWNTs with PU.