Synthesis and properties of novel polyurethane-urea/multiwalled carbon nanotube composites

In this paper, a new method based on sol-gel process was developed to prepare polymer/carbon nanotube composites. By modifying the multiwalled carbon nanotube (MWNT) with coupling agent, MWNT was introduced into the polyurethane-urea (PU) system by chemical linkages, and a series of novel self-cross-linkable PU/MWNT composites were then prepared. The obtained PU/MWNT composites with various MWNT contents are homogeneous and transparent materials. Mechanical property measurements show that a small amount of MWNT in the samples may increase the Young's modulus and tensile strength significantly with no loss of elongation, indicating that MWNT is an excellent reinforcing agent for polyurethane. The PU/MWNT composites also show good optical limiting properties. The normalized extinction increases and the optical limiting threshold decreases with the increase of the contents of MWNT. Thus, it is possible to change the required transmittance and transmitted energies by changing the MWNT contents in composites.