Xerogels made from aromatic polyureas

A xerogel comprising:

• from 30 to 90% by weight of a first monomer component comprising at least one polyfunctional isocyanate and
• from 10 to 70% by weight of a second monomer component comprising at least one polyfunctional aromatic amine;
• wherein at least one of the at least one polyfunctional aromatic amine is selected from the group consisting of 4,4′-diaminodiphenylmethane, 2,4′-diaminodiphenylmethane, 2,2′-diaminodiphenylmethane and oligomeric diaminodiphenylmethane;
• wherein a sum of the % by weight of the first and second monomer components is about 100% by weight;
• and
• wherein the first and second monomer components are present in polymeric form in the xerogel and a volume-weighted mean pore diameter of the xerogel is at most 5 μm.

A process for preparing xerogels, comprising

• providing a gel precursor comprising first and second monomer components in a solvent, wherein
• from 30 to 90% by weight of a first monomer component comprises at least one polyfunctional isocyanate and
• from 10 to 70% by weight of a second monomer component comprises at least one polyfunctional aromatic amine, wherein at least one of the at least one polyfunctional aromatic amine is selected from the group consisting of 4,4′-diaminodiphenylmethane, 2,4′-diaminodiphenylmethane, 2,2′-diaminodiphenylmethane and oligomeric diaminodiphenylmethane;
• wherein a sum of the % by weight of the first and second monomer components is about 100% by weight;
• and
• wherein the first and second monomer components are present in polymeric form in the xerogel and a volume-weighted mean pore diameter of the xerogel is at most 5 μm;
• converting the gel precursor in the presence of the solvent to a gel;
• and
• drying the resulting gel by converting the liquid present in the gel to the gaseous state at a temperature and a pressure below a critical temperature and a critical pressure of the liquid present in the gel.