Development of Mesoporous Carbon Cryogels with Desired Porous Characteristics by Using Sol-Gel Method and Freeze Drying

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In the present work, many kinds of carbon cryogels with unique mesoporous characteristics were prepared from resorcinol and formaldehyde by using sol-gel method and freeze drying. A method for controlling their porous properties was also proposed. The following results were obtained.1. The gelation process of resorcinol-formaldehyde (RF) aqueous solution was studied by using the light scattering experiment and the computer simulation based on the population balance model. It is found that the catalyst concentration in the RF aqueous solution is a main factor for determining the structure formation during the sol-gel transition.2. Carbon cryogels are successfully prepared from resorcinol and formaldehyde by using sol-gel method and freeze drying. The mesoporous properties of carbon cryogels are by no means inferior to those of the carbon aerogels prepared by supercritical drying.3. The influence of sol-gel condition of RF solution on mesoporous properties of carbon cryogels was investigated. It is found that their mesoporous properties are correlated with the catalyst concentration in the RF solution. The mesoporous properties of carbon cryogels can be controlled by changing the catalyst concentration.4. Carbon cryogel (CC) microspheres were successfully synthesized via an inverse emulsion polymerization of RF solution followed by freeze drying and pyrolysis in an inert atmosphere. CC micrspheres are confirmed to possess a dual structure, i.e. a mesoporous inner part covered by a microporous surface layer. It is possible to prepare both mesoporous microspheres and microspheres having utramicroporous surface which pore sizes can be controlled by changing the temperature of emulsion and the pyrolysis temperature. CC microspheres are demonstrated to be potential carbons, which are applicable to column packing materials for HPLC although further investigation is necessary for improving their performances.