Experimental and molecular simulation study for the preparation of ordered mesoporous carbons

Abstract

In recent years a number of mechanisms for the preparation of ordered mesoporous carbons (OMCs) have been proposed for different systems. However, the exact preparation mechanism for the soft template method remains unclear, which seriously inhibits the further design and development of OMC materials on the molecular level, as well as better understanding of the related structure-activity relationship and their wider application. To clarify the mechanisms involved in the preparation of OMCs via the soft-template method, experimental and molecular simulation studies were performed in this work. First, OMCs were prepared using a triblock copolymer Pluronic F127 as the template and phenolic resin as the carbon source. These OMCs were characterized using X-ray diffraction (XRD), N2 adsorption-desorption and transmission electron microscopy (TEM), and the results show that the OMCs have well-ordered 2D-hexagonal structures and narrow pore size distributions. Additionally, the dissipative particle dynamics (DPD) method was carried out to investigate the phase behavior and self-assembly process of the F127/phenolic resin/ethanol system. The simulation results show that F127 could self-assemble a series of stable micellar structures at different concentrations, such as spherical, cylindrical, lamellar, body-centered cubic and cubic perforative ones. These micellar structures, similar to the template used in the experiment, controlled the structure of phenolic resin in ethanol solution, while the introduction of phenolic resin did not affect the selfassembled structure of F127. An investigation of the dynamic formation process involved in production of the cylindrical micelles indicates that the system transformed from a homogeneous state into the typical stable micellar structures due to their amphiphilic properties, which explains why cylindrical and uniform mesopores of OMCs were experimentally obtained. This work deepens our understanding of the mechanisms involved in the preparation of OMCs on a mesoscopic level. It also demonstrates that the DPD method is effective for studying the self-assembly of polymer systems, and provides useful guidance for the fabrication of novel materials. © Taiwan Association for Aerosol Research.