A study on the effect of surface treatment of carbon nanotubes for liquid crystalline epoxide–carbon nanotube composites

Abstract

Chemical surface oxidation of carbon nanotubes was employed to modify the interfaces between liquid crystalline epoxide (LCE) molecules and carbon nanotubes (CNs). Polar functional groups are formed on the surfaces of the carbon nanotubes as a result of the treatment. The thermotropic behavior of the nematic liquid crystalline (LC) phase in liquid crystalline epoxide–carbon nanotube (LCE–CN) composites has been examined using polarized optical microscopy. The LC phase in the LCE–surface oxidized CN composite evolves at a lower temperature compared to that for LCE–CN, due to polar interactions. The mechanical properties of LCE–CN composites tend to increase with increasing CN content. The electrical conductivity of LCE–CN composites was found to increases dramatically compared to that of pristine LCE resin, up to 5 wt% CN loading, and then increase linearly with increasing CN content at high CN loadings. An investigation of the thermal properties of LCE–CNs in relation to the surface treatment of CNs was also undertaken. Surface oxidation of CNs was found to improve the mechanical durability and thermal stability of LCE–CN composites.