Inorganic block co-polymers and other similar materials as ceramic precursors for nanoscale ordered high-temperature ceramics
The present invention is generally directed to methods of making ceramics with nanoscale/microscale structure involving self-assembly of precursor materials such as, but not limited to, inorganic-based block co-polymers, inorganic-/organic-based hybrid block co-polymers, and other similar materials, and to the structures made by such methods. Where such precursor materials are themselves novel, the present invention is also generally directed to those materials and their synthesis.
1. A method comprising the steps of:
dissolving a block co-polymer in which at least one of the blocks comprises residues of norbornene or substituted norbornene in a solvent, wherein the block co-polymer comprises at least two blocks that differ in their ability to segregate into at least two phases, and wherein the molecular structure of at least one of the two blocks comprises inorganic elemental constituents suitable for forming a ceramic structure upon pyrolysis;
evaporating the solvent to cause self-assembly of the block co-polymer into an ordered primary structure having dimensionality in the range of from about 1 nm to about 100 μm; and
pyrolyzing the primary structure to form a secondary ceramic structure, wherein the inorganic elemental constituents of the at least one block are retained during pyrolysis to form the secondary ceramic structure.
2. The method of claim 1 , wherein the block co-polymer is a hybrid block co-polymer.
3. The method of claim 1 , further comprising a step of adding a ceramic precursor additive.
4. The method of claim 3 , wherein the ceramic precursor additive is selected from the group consisting of polysilazane, polycarborane, polyureasilazane, polysilane, polycarbosilane, polyborazine, polyborazylene, polysiloxane, and combinations thereof.
5. The method of claim 1 , wherein the pyrolysis step leads to the formation of a ceramic product selected from the group consisting of a porous ceramic structure, a densified ceramic structure, and combinations thereof.
6. The method of claim 5 , wherein the ceramic product comprises a composition selected from the group consisting of silicon carbide, silicon nitride, silicon carbonitride, silicon oxynitride, silicon boron carbonitride, boron nitride, boron carbide, boron carbonitride, silicon oxycarbide, and combinations thereof.
7. The method of claim 1 wherein the block co-polymer is a co-polymer of polynorbornene and polynorbornenedecaborane.