Effect of Catalysts on the Morphologies of Carbon Materials Synthesized by an Emulsion Templating Method

An oil in water (O/W) emulsion with a resorcinol and formaldehyde (R+F) water solution as the external phase and liquid paraffin as the internal phase together with Span 80/Tween 80 as emulsifiers was obtained. Carbon materials were prepared by polymerization of the emulsion, followed by carbonization for template removal. The effect of catalysts on the morphologies of the carbon materials was investigated. The results indicate that the resultant representative carbons are a type of porous carbon foam and possess pore walls and pores of 1-2 mu m in size when NaOH is used as a catalyst. However, monolithic carbon materials consisting of microspheres or intertwinded wormlike particles were prepared using ammonia as an alternative catalyst. The diameters of these microspheres or particles were mainly around 1-2 mu m and these dimensions are similar to the pore sizes of the carbon foams. We find that ammonia causes the initial O/W emulsion system to experience a phase inversion toward a W/O high internal phase emulsion. A mechanism involving intermolecular II-bond interactions and cohesive energy theory is proposed to explain the catalyst. induced phase inversion phenomenon as well as the formation of carbon materials with different morphologies.