Refractive index matching base resin for extremely fine three-dimensional ceramic structures

1. An optically clear resin for additive manufacturing, the resin comprising:

an optically clear ceramic precursor having a pre-defined refractive index,

wherein each molecule of the ceramic precursor has at least two photopolymerizable functional groups and at least one refractive index-tuning group that is different than the photopolymerizable functional groups thereby causing the ceramic precursor to have the pre-defined refractive index,

wherein one or more of the at least one refractive index tuning group is a thiolphenol group, wherein the thiolphenol group is an end group,

wherein at least one of the at least two photopolymerizable functional groups includes an acrylate group,

wherein the molecule of the ceramic precursor is a polyhedral oligomeric silsesquioxane.

2. The resin as recited in claim 1 , wherein each molecule of the ceramic precursor has up to six photopolymerizable functional groups.

3. The resin as recited in claim 1 , wherein at least one of the other of the at least two photopolymerizable functional groups is selected from the group consisting of: methyl acrylate, acrylate, allyl, and a combination thereof.

4. The resin as recited in claim 1 , wherein the ceramic precursor includes at least one non-photopolymerizable group selected from the group consisting of: a hydroxyl group and an amino group.

5. The resin as recited in claim 1 , wherein the pre-defined refractive index is 1.52±0.005.

6. The resin as recited in claim 1 , wherein the resin is essentially free of particles.

7. The resin as recited in claim 1 , wherein the resin is a single phase system.

8. The resin as recited in claim 1 , wherein the additive manufacturing is a direct laser writing technique, wherein the pre-defined refractive index of the ceramic precursor is configured to match a focusing optic of a machine performing the direct laser writing technique.

9. The resin as recited in claim 1 , comprising a photoinitiator, wherein a concentration of the photoinitiator in the resin is in a range of about 0.05 wt. % to about 1.0 wt. % of weight of total resin.

10. The resin as recited in claim 1 , wherein the molecule of the ceramic precursor has a structure as follows:

wherein R individually is —CH 2 CH 2 CH 2 OC(O)CH═CH 2 or

—CH 2 CH 2 CH 2 OC(O)CH 2 CH 2 SPh, wherein the structure has at least two acrylate end groups.

11. The resin as recited in claim 10 , wherein the pre-defined refractive index of the molecule of the ceramic precursor is in a range of 1.42 to 1.57.

12. A method of forming a self-supporting ceramic structure using the optically clear resin as recited in claim 1 , wherein the ceramic structure has a pre-defined geometric arrangement of features, wherein the features have an average diameter in a range of greater than about 50 nanometers to less than 300 nanometers, the method comprising:

forming a three-dimensional structure by additive manufacturing using the resin; and

heating the formed three-dimensional structure for transformation to the self-supporting ceramic structure.

13. The method as recited in claim 12 , wherein each molecule of the ceramic precursor has up to six photopolymerizable functional groups.

14. The method as recited in claim 12 , wherein forming the three-dimensional structure comprises using a dip-in mode of direct laser writing via two photon polymerization.

15. The method as recited in claim 12 , wherein forming the three-dimensional structure comprises using direct laser writing, wherein the pre-defined refractive index of the ceramic precursor is configured to match a focusing optic of a machine performing the direct laser writing.

16. The method as recited in claim 12 , wherein a temperature of the heating is in a range of above about 500 degrees Celsius to about 1500 degrees Celsius.