Highly porous and mechanically strong ceramic oxide aerogels
Structurally stable and mechanically strong ceramic oxide aerogels are provided. The aerogels are cross-linked via organic polymer chains that are attached to and extend from surface-bound functional groups provided or present over the internal surfaces of a mesoporous ceramic oxide particle network via appropriate chemical reactions. The functional groups can be hydroxyl groups, which are native to ceramic oxides, or they can be non-hydroxyl functional groups that can be decorated over the internal surfaces of the ceramic oxide network. Methods of preparing such mechanically strong ceramic oxide aerogels also are provided.
1. A structure comprising a solid-phase three-dimensional network of ceramic oxide particles having functional groups bound to surfaces of said particles, said network of ceramic oxide particles being cross-linked via organic polymer chains that are attached to said particles via reaction with at least a portion of said surface-bound functional groups, said ceramic oxide having the form ZO x where ‘Z’ is a metallic or semimetallic element other than silicon.
2. A structure according to claim 1 , said surface-bound functional groups comprising hydroxyl groups native to ceramic oxides.
3. A structure according to claim 2 , said surface-bound functional groups further comprising non-hydroxyl functional groups.
4. A structure according to claim 1 , said polymer chains being polyurea chains extending from or between, and linked to, surfaces of said ceramic oxide particles via carbamate linkages formed through reaction between a surface-bound hydroxyl group and an isocyanate group on an organic polymer or polymerizable species.
5. A structure according to claim 4 , said metallic or semimetallic element being an element selected from the group consisting of: Sc, Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and V.
6. A structure according to claim 1 , wherein ‘Z’ is a mixture of metallic or semimetallic elements other than silicon, such that said ceramic oxide is a composite ceramic oxide composed of a plurality of species of metallic and/or semimetallic atoms linked via interposed oxygen atoms.
7. A structure according to claim 1 , said three-dimensional network of ceramic oxide particles being in the form of a dried aerogel that is cross-linked via said organic polymer chains, said polymer cross-linked aerogel having a bulk density not more than about 10 times greater than the bulk density of the corresponding uncross-linked aerogel, but at least 10 times greater elastic modulus than the corresponding uncross-linked aerogel.
8. A structure according to claim 7 , said polymer cross-linked aerogel having an elastic modulus that is at least 100 times greater than the elastic modulus of the corresponding uncross-linked aerogel.
9. A structure according to claim 8 , said polymer cross-linked aerogel having a bulk density not more than about 3 times greater than the bulk density of the corresponding uncross-linked aerogel.