Low density, resorcinol-formaldehyde aerogels
US4997804A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 12, 1989 |
| Grant date | Mar 5, 1991 |
| Priority date | — |
| Expiry date | Sep 12, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S521/918
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "Clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density.ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100.circle.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron. TABLE I ______________________________________ Theo- [Form- retical Actual Formu- % alde- [Resor- density Density lation Solids hyde] cinol] Na.sub.2 CO.sub.3 (g/cc) (g/cc) ______________________________________ A 5.0% 0.29M 0.58M 0.0029M 0.050 0.079 B 5.0% 0.29M 0.58M 0.0019M 0.050 0.073 C 5.0% 0.29M 0.58M 0.0015M 0.050 0.070 D 4.0% 0.24M 0.47M 0.0012M 0.040 0.054 E 3.5% 0.21M 0.41M 0.0010M 0.035 0.044 F 2.0% 0.12M 0.24M 0.0006M 0.020 0.030 ______________________________________
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.