Influence of freeze-drying conditions on the mesoporosity of organic gels as carbon precursors

Resorcinol-formaldehyde (RF) gels were synthesized by sol-gel polycondensation of resorcinol with formaldehyde to prepare mesoporous carbon precursors. RF cryogels were prepared by freeze drying of RF gels, where t-butanol and water were used as solvents. The freezing temperature, the number of repetitive rinse times with t-butanol, and the sample size were changed in the preparation of RF cryogels. Porous properties of the RF cryogels were estimated by N-2 adsorption. The influence of freeze-drying conditions was elucidated on the mesoporosity of RF cryogels. Freeze drying of RF gels with t-butanol developed more mesopores than freeze drying with water. The freezing temperature of the gels did not greatly influence the porous properties of the cryogels. If the gels were repeatedly rinsed with t-butanol and freeze-dried in smaller sizes, the cryogels were favorable for use as mesoporous carbon precursors. (C) 2000 Elsevier Science Ltd. All rights reserved.