Preparation and characterisation of polyurethane grafted single-walled carbon nanotubes and derived polyurethane nanocomposites

Polycaprolactone (PCL) polyurethane (PU) grafted single-walled carbon nanotubes (SWNT-g-PU) were synthesized from hydroxyl functionalized single-walled carbon nanotubes (SWNT-OH) through a two-step reaction. Based on SWNT-g-PU, PCL polyurethane (PU)/SWNT nanocomposites were prepared by further in-situ polymerization. The results suggested that SWNT-g-PU improved the dispersion of SWNT in the PU matrix and strengthened the interfacial interaction between the PU and SWNT. The incorporation of SWNT-g-PU in the PU matrix improved the phase separation and the degree of crystallization of PCL soft segments, improved the thermal stability and depressed the increment of heat capacity, while pristine SWNT has some slight or inverse effects on these aspects. SWNT-g-PU has a more remarkable effect on Young's modulus compared with pristine SWNT. At 0.7 wt% SWNT-g-PU concentration, the Young's modulus was improved by similar to 278% compared to the blank PU, and by similar to 188% compared to 0.7 wt% ungrafted pristine SWNT/PU. The remarkable reinforcing effects of SWNT-g-PU may be related to better dispersion of SWNT-g-PU and stronger interfacial interactions between the PU and SWNT. This study could open up a new route for the preparation of high performance polyurethane/SWNT composites.