Aerogel polyurethane gels

Figure 10.16. Illustration of the densification occurring during evaporative drying of polyurethane gels xerogel (left) versus aerogel (right). Both samples come from gels synthesized with pentaerythritol in solution of DMSO and etac with a volume fraction of DMSO >0.3. Diameters of the xerogel and the aerogel are 3 and 5 cm, respectively.

In analogy to their resorcinol-formaldehyde homologues, polyurethane wet gels are synthesized by polycondensation. Subsequently, aerogels are commonly obtained by supercritical fluid drying of the organic wet gels [23]. 

Figure 10.12. Photograph of a polyurethane aerogel obtained by supercritical CO2 drying of a gel synthesized by cross-linking of pentaerythritol with 4,4-diphenyhnethane diisocyanate under DABCO catalysis.

Figure 10.14. SEM micrographs of polyurethane aerogels coming frcm supercritical CO2 drying of gels synthesized with saccharose in different solutions of DMSO and etac with volume fraction ofDMSO <0.3 (top) and >0.3 (bottom) (microscopy conducted by M. Repoux at MINES ParisTech/CEMEF, Sophia AntipoUs, France) [39].

Yim T-J, Kim SY, Yoo K-P (2002) Fabrication and thermophysical characterization of nanoporous silica-polyurethane hybrid aerogel by sol-gel processing and supercritical solvent drying. Korean J. Chem. Eng. 19(1) 159-166. 

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