| 초록 |
Carbon nanotubes(CNTs) have attracted considerable attention since their discovery due to its unique mechanical, thermal, and electrical properties. However, CNTs have strong van der Waals interactions, high aspect ratios and specific surface areas, which lead to aggregation and the formation of bundles. Various surface modification and functionalization techniques have been studied for effective introduction of functional groups on CNT surfaces. Acid treatment using HNO3/H2SO4 is a representative method for introducing oxygen-containing groups such as carboxyl and hydroxyl groups onto the CNT surfaces. However, it not only creates defects on the CNT sidewalls, but also decreases the aspect ratio of the CNTs because strong acids cut the CNTs into short pieces during the oxidative process, which leads to degradation the original mechanical properties of the CNTs. In recent UV/ozone treatment of CNTs has been developed as an alternative, milder route to utilize it in various high performance applications. UV/ozone treatment has many advantages, the oxidation process can be carried out in an air atmosphere, and, when compared with the high vacuum plasma process, the equipment and operating cost are relatively low. Solubility evaluation of CNTs is essential to determine its applications. Solubility parameters utilized in polymer solubility theory have been considered to describe the behavior of CNT-solvent mixtures. Hansen solubility parameters(HSP) are widely used for predicting compatibility between two materials. In this study, we evaluated the enhanced dispersion stability of UV/ozone treated MWCNTs using light-scattering and developed a simple model to estimate the solubility behavior of MWCNTs with controlled UV/ozone treatment time using the HSP in 32 different organic solvents. Moreover, based on this solubility data, MWCNT/PMMA composites were prepared using the chosen solvent and were investigated in terms of the electrical properties of three kinds of composites. |
