Organic aerogel microspheres and fabrication method therefor

A method for producing organic aerogel microspheres having a diameter in the range of 1-1000 .mu.m comprising the steps of:

• forming an aqueous solution containing at least reactants including a monomer and a catalyst;
• mixing the thus formed aqueous solution with an excess of a non-polar, water insoluble solvent;
• stirring the thus formed mixture so as to form an emulsion with continuous oil phase, and forming microspheres in a non-continuous aqueous droplet phase;
• continuing stirring for a period of time so that the microspheres are hardened;
• washing the microspheres with a solvent and concurrently exchanging water in the aquagel microspheres with the solvent;
• and
• exchanging the solvent with liquid carbon dioxide via extraction of the solvent with the carbon dioxide to produce solvent-free aerogel microspheres.

A method of producing resorcinol/formaldehyde carbon aerogel microspheres, comprising the steps of:

• mixing resorcinol, formaldehyde, deionized water and 0.1M sodium carbonate to form an aqueous solution of a 2:1 molar ratio of formaldehyde to resorcinol and a 30% weight/volume fraction of reactants;
• mixing the aqueous solution with an excess of a non-polar, water insoluble solvent selected from the group of mineral oil, cyclohexane, saturated hydrocarbons, and p-xylene;
• adding to the mixture a surfactant;
• stirring the mixture vigorously for forming an inverse emulsion with the oil phase being continuous and the RF aquagel forming in a non-continuous aqueous droplet phase;
• continuing stirring for a period of about 5 hours causing the aqueous droplets to harden producing microspheres;
• filtering and washing the RF microspheres with acetone to remove the oil phase and concurrently exchange the water therein with acetone;
• exchanging the acetone with liquid carbon dioxide via a supercritical extraction or a non-supercritical extraction technique to produce RF aerogel microspheres;
• and
• firing the RF aerogel microspheres in an inert or oxidizing atmosphere to form carbon aerogel microspheres.

A method for fabricating organic aerogel microspheres by inverse emulsion polymerization, wherein the size of the microspheres is determined by the processing procedures and the chemical formulation, comprising the steps of:

• mixing selected reactants including a monomer with at least a catalyst to form an aqueous solution;
• mixing the thus formed aqueous solution with a non-miscible solvent forming an inverse emulsion;
• heating the thus formed mixture to a temperature in the range of 20.degree.-100.degree. C.;
• stirring the heated mixture to form a colloidal suspension of aqueous phase droplets in a continuous oil phase;
• continuing stirring of the heated mixture until the aqueous phase undergoes gelation and microspheres are formed;
• removing the oil phase from the surface of the thus formed microspheres;
• removing water from within the thus formed microspheres;
• and
• drying the thus formed microspheres.