High strength air-dried aerogels
AssigneeThe Regents of the University of California
InventorsPaul Coronado, Joe Satcher
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Abstract
A method for the preparation of high strength air-dried organic aerogels. The method involves the sol-gel polymerization of organic gel precursors, such as resorcinol with formaldehyde (RF) in aqueous solvents with R/C ratios greater than about 1000 and R/F ratios less than about 1:2.1. Using a procedure analogous to the preparation of resorcinol-formaldehyde (RF) aerogeis, this approach generates wet gels that can be air dried at ambient temperatures and pressures. The method significantly reduces the time and/or energy required to produce a dried aerogel compared to conventional methods using either supercritical solvent extraction. The air dried gel exhibits typically less than 5% shrinkage.
Claims25
A process for the synthesis of a low density, organic aerogel the process comprising the steps of:
- mixing a hydroxy benzene and an aldehyde in a solvent in the presence of a catalyst, the hydroxy benzene and aldehyde present in a ratio of less than about 1:2.1;
- heating the mixture to sufficient temperature for a sufficient time to form a stable gel;
- and
- allowing the gel to dry whereby a stable, low-density monolithic structure results.
A process for the synthesis of a low density;
- high strength organic aerogel of fine pore size, said process comprising the steps of:
- mixing in a predetermined ratio a polyhydroxy benzene and formaldehyde in the presence of a base catalyst;
- heating the mixture to a predetermined temperature for a sufficiently long period of time to form a stable gel;
- and
- air drying the gel whereby a low density, high strength monolithic aerogel, exhibiting less than about 8% shrinkage, results.
A process for forming a low density, high strength organic aerogel, comprising
- (a) forming a reaction mixture comprising at least one hydroxylated benzene compound, at least one aldehyde, a catalyst and solvent;
- wherein the molar ratio of the hydroxylated benzene compound to aldehyde is less than about 1:2.1;
- (b) reacting said reaction mixture at a temperature and for a time sufficient to form an organic gel;
- (c) heating said organic gel at a curing temperature for a curing time to form a cured organic gel;
- and
- (d) allowing the resultant gel to air dry whereby a low density, high strength monolithic aerogel, exhibiting less than about 5% shrinkage, results.
An organic resorcinol formaldehyde aerogel, characterized by a high strength, non friable monolithic structure, having a density of between about 50 and 240 mg/cm3 and a surface area of at least about 400 m2/g, wherein the aerogel is derived from air drying an organic resorcinol formaldehyde gel.
Dependencies are inferred from the claim text.