This study demonstrates that mechanically robust antimicrobial nanocomposites of multiwalled carbon nanotubes (MWCNTs) and hyperbranched polyurethane (HBPU) can be prepared via a click chemistry reaction. Various compositions of HBPU-functionalized MWCNTs were synthesized from reactions of azide moiety-containing HBPU with alkyne-functionalized MWCNTs. The HBPU-functionalized MWCNTs were characterized morphologically using transmission electron microscopy and field emission scanning electron microscopy and chemically using Fourier transform infrared spectrometry, Raman spectroscopy, and X-ray photoelectron spectroscopy. The functionalized MWCNTs exhibited excellent dispersion in the HBPU matrix, and as a result, superior mechanical and strong antibacterial properties were obtained. The antimicrobial properties were examined by use of gram-negative bacteria Escherichia coil (E. coli). Consequently the click coupled bonding of MWCNTs with HBPU was very efficient for regulating the composite properties and achieving high performance materials. (C) 2012 Elsevier Ltd. All rights reserved.