Xerogel based on polyurea

摘要

Xerogel comprises: 20-90 wt.% of a monomer component (a1) made of at least one multifunctional isocyanate; and 10-80 wt.% of a monomer component (a2) made of at least one multifunctional aliphatic amine, where: the total weight of the monomer components (a1) and (a2) is 100 wt.%; the monomer components are present in the xerogel in polymer form; and the volume-weighted average pore diameter of the xerogel is not more than 5 mu m. An independent claim is included for producing xerogels, comprising: (a) providing the monomer components (a1) and (a2) in more separate form; (b) fusing the components (a1) and (a2) in the presence of a solvent; reacting the monomer components (a1) and (a2) in the presence of the solvent to a gel; and (c) drying the obtained gel by transferring the liquid contained in the gel into the gaseous condition at a temperature and a pressure below the critical temperature and the critical pressure of the liquid contained in the gel.