Direct Formation of Phenolic/Furfural Aerogel Microspheres in Supercritical CO₂^†

† Part of this paper was presented at 74th Colloid and Surface Science Symposium, June 2000, Pennsylvania, U.S.A.

Abstract

P/F aerogel microspheres were successfully produced in one-step method by sol-emulsion-gel technique in supercritical CO₂. The solubility of alcohol in supercritical CO₂ varied with temperature and pressure of the system. When the dispersion phase is insoluble in supercritical CO₂, it could be emulsified in CO₂ by means of a CO₂-soluble stabilizer with high temperature and low pressure, phase separation occurred and led to the formation of phenolic/furfural (P/F) gel microspheres. At the inversion of process condition, alcohol in the P/F gel microspheres was then exchanged with supercritical CO₂ continuously, which was supercritically dried to obtain organic aerogel microspheres. CO₂-soluble poly(-dimethylsiloxane) (PDMS) was used as the stabilizer in this system. Spherical morphology of the gel microspheres was confirmed by scanning electron microscopy. Particle size and particle size distribution of P/F aerogel microspheres can be modified upon variation of the solids and the stabilizer content. The resultant P/F aerogel microspheres have average particle size in the range of 1–6μm. The pore surface area of P/F aerogel microspheres can be modified upon variation of the solids content and phenolic/catalyst (P/C) weight ratio.

† Part of this paper was presented at 74th Colloid and Surface Science Symposium, June 2000, Pennsylvania, U.S.A.

Keywords:

• Direct process
• P/F Aerogel microspheres
• Sol-emulsion-gel technique
• Supercritical CO₂

ACKNOWLEDGMENT

The authors acknowledge the financial support of the Korea Institute of S&T Evaluation and Planning (KISTEP) made in the program year of 1999.

Notes

† Part of this paper was presented at 74th Colloid and Surface Science Symposium, June 2000, Pennsylvania, U.S.A.