Preparation of urea functionalized carbon nanotubes

The incorporation of carbon nanotubes (CNTs) within polymer matrices has emerged as an area of intense nanocomposite research, which is focused on developing polymeric materials with enhanced mechanical, electrical, and thermal properties. Multi-walled carbon nanotubes (MWNT) were oxidized in nitric acid to produce acid sites decorating the NT surface at a concentration of 1.30 mmol COOH groups/g MWNT. These were then converted to acid halides and reacted with various diamines of different spacer lengths. The amines moieties were reacted with octadecyl isocyanate to produce urea modified MWNTs (0.32 mmol Urea/g MWNT). Spacer groups were introduced between the urea group and CNT surface to disperse CNT-CNT aggregation. These urea functionalized CNTs were dispersed in poly(urethanes) and poly(urethane ureas) in order to study the influence of hydrogen bonding moieties (ureas) on the CNT surface and polymer matrix. MWNTS were characterized with thermogravimetric analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy.