Optical article and method of forming

1. A method of forming an optical article, comprising:

applying a silicone composition to a surface, wherein the silicone composition is a solid and has a glass transition temperature greater than room temperature; and

heating the silicone composition to a temperature at or above the glass transition temperature such that the silicone composition flows;

wherein:

the silicone composition forms a light transmitting sheet upon cooling following the heating; and

the silicone composition comprises an organosiloxane block copolymer having a weight average molecular weight of at least 20,000 g/mole and comprises:

40 to 90 mole percent disiloxy units of the formula [R 1 2 SiO 2/2 ] arranged in linear blocks each having an average of from 10 to 400 disiloxy units [R 1 2 SiO 2/2 ] per linear block;

10 to 60 mole percent trisiloxy units of the formula [R 1 2 SiO 3/2 ] arranged in non-linear blocks each having a weight average molecular weight of at least 500 g/mole; and

0.5 to 25 mole percent silanol groups [≡SiOH];

wherein R 1 is independently a C 1 to C 30 hydrocarbyl and R 2 is independently a C 1 to C 20 hydrocarbyl,

wherein at least 30 weight percent of the non-linear blocks are crosslinked with another non-linear block and aggregated in nano-domains, and

wherein each linear block is linked to at least one non-linear block.

2. The method of claim 1 , wherein the surface is an optical surface of an optical device.

3. The method of claim 2 , wherein the silicone composition is a pellet, spheroid, ribbon, sheet, cube, powder, film, flake or sheet.

4. The method of claim 3 , wherein the silicone composition is a sheet, wherein the sheet has a major surface, and wherein placing the sheet against the optical surface comprises placing the major surface of the sheet against the optical surface.

5. The method of claim 1 wherein the light transmitting sheet is substantially free of visible air bubbles.

6. The method of claim 1 wherein the light transmitting sheet has a light transmittance of at least 95% as determined using ASTM D1003.

7. The method of claim 1 further comprising curing the silicone composition via a condensation reaction.

8. The method of claim 7 wherein the curing occurs at a temperature higher than the glass transition temperature of the silicone composition.

9. The method of claim 1 , wherein the disiloxy units have the formula

[(CH 3 )(C 6 H 5 )SiO 2/2 ].

10. The method of claim 1 , wherein the organosiloxane block copolymer comprises at least 30 weight percent disiloxy units.

11. The method of claim 1 , wherein R 2 is phenyl.

12. The method of claim 1 wherein the silicone composition has a tensile strength greater than to MPa and an % elongation at break greater than 20% as determined using ASTM D412.

13. The method of claim 1 wherein the glass transition temperature of the silicone composition is from 25° C. to 200° C.

14. The method of claim 1 wherein the light transmitting sheet has a thickness from 10 micrometers to 1 mm.

15. The method of claim 1 wherein the light transmitting sheet is a monolayer.

16. A composite article comprising first and second light transmitting sheets each independently formed by the method of claim 1 wherein the first light transmitting sheet is a first outermost layer of the composite article and the second light transmitting sheet is a second outermost layer of the composite article.