Hyperbranched polyol decorated carbon nanotube by click chemistry for functional polyurethane urea hybrid composites

Abstract

In the present work we report a facile decoration of multi-walled carbon nanotubes with hyperbranched polyether polyol using copper(I) catalyzed azide–alkyne click reaction in order to create hydroxy terminal groups. This decoration has been designed to improve the dispersibility of CNTs in the polymer matrix. These hydroxy functional decorated CNTs were then dispersed into poly(tetramethylene ether) glycol (PTMG) at different weight percentages to get the hybrid pre-polymers. These pre-polymers were reacted with 1-isocyanato-4-[(4-isocyanatocyclohexyl) methyl] cyclohexane (H₁₂-MDI) at a NCO : OH ratio of 1.2 : 1 and cured under atmospheric moisture to get the functional polyurethane–urea–CNT hybrid composites. There has been substantial improvement in the thermal stability, mechanical strength, corrosion resistance and antimicrobial activity of the polyurethane hybrid composites with the increase in carbon nanotube loading in pre-polymers. For example, with 2 wt% loading of carbon nanotubes, the tensile strength of the polyurethane hybrid composite improved from 1.25 N mm⁻² to 6.25 N mm⁻²; the water contact angle improved from 54° to 108° and also the rate of corrosion reduced from 0.047 mm per year to 0.0019 mm per year. We also observed that these hybrids possess remarkable shape recovery properties. These results demonstrate that the decorated CNTs can be used as high performance additives for improving various properties of polyurethane hybrids in cost effective and eco-friendly ways.