The effects of different synthetic conditions on the porous properties of carbon cryogel microspheres

Carbon cryogel microspheres (CC microspheres) are synthesized through the inverse emulsion polymerization of a resorcinol-formaldehyde (RF) aqueous Solution ill cyclohexane using SPAN80 as an emulsifier. The conditions of the inverse emulsion polymerization, specifically the volume ratio of SPAN80 to cyclohexane, the temperature of the emulsification, T-gel and the holding time after the emulsification, are examined. It is revealed that the RF aqueous solution is dehydrated by cyclollexane containing SPAN80 during the inverse emulsion polymerization, and that the degree of dehydration can be changed by varying T-gel. In the case of a T-gel, lower than 313 K. this dehydration leads to the formation of ultramicroporous surfaces on the CC microspheres. Conversely, a T-gel higher than 323 K results in the suppression of dehydration, which in turn leads to mesoporous CC microspheres. The mesoporosity of the microspheres synthesized at T-gel = 333 K can be changed by varying the amount of basic catalyst used in the preparation of the RF aqueous solution. (c) 2005 Elsevier Ltd. All rights reserved.