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.
Highlights
In recent years, ordered mesoporous carbons (OMCs) have been of great interest for use in various applications, including fuel cell catalyst supports, super-capacitor carbon electrodes, chromatography separation, hydrogen storage/ conversion devices, adsorption to large molecules and desulfurization for clean energy (Zhao et al, 1998; Lee etWang et al, Aerosol and Air Quality Research, 13: 1034–1044, 2013One challenge in the synthesis of OMCs is in controlling their mesopore sizes and the pore sizes distributions, which are not typically uniform for the catalytic activation, polymer blending carbonization and organic aerogel carbonization methods (Tamon et al, 1998; Kyotani, 2000; Kim and Pinnavaia, 2001)
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
(2) For the F127/Phenolic resin/Ethanol system, a series of typical and stable micellar structures were shown at different F127 concentrations, such as spherical, cylindrical, lamella, body-centered cubic and cubic perforative
Summary
In recent years, ordered mesoporous carbons (OMCs) have been of great interest for use in various applications, including fuel cell catalyst supports, super-capacitor carbon electrodes, chromatography separation, hydrogen storage/ conversion devices, adsorption to large molecules and desulfurization for clean energy (Zhao et al, 1998; Lee etWang et al, Aerosol and Air Quality Research, 13: 1034–1044, 2013One challenge in the synthesis of OMCs is in controlling their mesopore sizes and the pore sizes distributions, which are not typically uniform for the catalytic activation, polymer blending carbonization and organic aerogel carbonization methods (Tamon et al, 1998; Kyotani, 2000; Kim and Pinnavaia, 2001). The soft template method has been of great interest for the synthesis of OMCs. Up to now, researchers have proposed many mechanisms for the preparation of OMCs, including the liquid crystal template mechanism (Beck et al, 1992), the cooperative formation mechanism (Huo et al, 1994; Wan et al, 2007), the charge density matching mechanism (Monnier et al, 1993; Schmidt et al, 2000), the generalized liquid crystal template mechanism (Huo et al, 1994; Firouzi et al, 1997), the silicate layer puckering mechanism (Inagaki et al, 1993; Göltner et al, 1998) and the silicate rod assembling mechanism (Chen et al, 1993). The exact preparation mechanism of OMCs for soft template method, is still ambiguous and not clear fully which inhibits seriously the further development of OMCs materials design on molecular level, structure-activity relationship and their wider application
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
