Three types of amine-containing polyurethanes and poly(urethane−ureas), N-methyldiethanolamine (MDEA) and/or tetraethylenepentamine (TEPA) as the chain extender and poly(ethylene glycol) of MW 400 as the soft-segment component, have been studied by FTIR. The hydrogen bonding in hard and soft segments was examined for the extent of phase separation, and the microstructure was evidenced by differential scanning calorimetry (DSC). The temperature effects on the hydrogen bonding were also investigated. They show a significant amount of hydrogen bonding between the hard and soft segments. It indicates that there exists a large amount of partial phase mixing of hard and soft segments compared to the conventional polyurethanes. The bulky CH3 groups of MDEA in hard segments restrict the hydrogen bonding within the hard segments, while the TEPA-containing urethane−urea polymers have more distinct phase separation. However, all of the polymers studied are amorphous materials such that the dissolved soft segments in the hard-segment domains may interfere with molecular packing in the domains. It shows that the hydrogen bonding in these polymers persists up to 200 °C. The hydrogen bonding of NH to the ether oxygen decreases significantly at T > 50 °C.

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A novel method for preparing a fully integrated nanotube composite material through the use of functionalized multi-walled carbon nanotubes (MWNTs) is presented in this study. The functionalization of MWNTs was performed via plasma treatment; subsequently, maleic anhydride (MA) was grafted onto the MWNTs (CNTs-MA). Nanotube-reinforced epoxy polymer composites were prepared by first mixing the CNTs-MA and a diamine curing agent, followed by a further reaction with the epoxy matrix. In this hybrid nanocomposite system, the CNTs-MA were covalently integrated into the epoxy matrix and became part of the cross-linked structure rather than just a separate component. Fourier transform infrared (FT-IR) and high resolution X-ray photoelectron (XPS) spectroscopes were used to characterize the functional groups on the surface of the MWNTs after the plasma modification. In addition, observations of scanning electronic microscopy (SEM) and transmission electron microscopy (TEM) images showed that the functionalized nanotubes, CNTs-MA, had a better dispersion than the unfunctionalized nanotubes, u-CNTs, on either the composite fracture surfaces or inside the epoxy matrix. Moreover, CNTs-MA/ epoxy nanocomposites presented obvious improvements in mechanical properties and conductivity (from 10 -12 to 10 -4 S/m) with only a small quantity (0.1-1.0 wt %) of the CNTs-MA addition.

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