Polyheterosilxoanes for high refractive index materials

1. A polyheterosiloxane composition comprising at least 70% by weight of:

(A) a first metal (M1) selected from Ti, Zr, or Zn,

(B) a second metal (M2) selected from a non-lanthanide metal, provided the metal selected for the second metal M2 is different from the first metal Ml,

(C) siloxy units having the formula R 1 2 SiO 2/2 or R 1 SiO 3/2

where R 1 is independently a hydrocarbon group or halogen substituted

hydrocarbon group containing 1 to 30 carbon atoms,

wherein:

the mole fraction of components (A), (B), and (C) in the polyheterosiloxane composition relative to each other is of the formula [M1] a [M2] b [R 1 2 SiO 2/2 ] c [R 1 SiO 3/2 ] d

where a may vary from 0.10 to 0.7,

b may vary from 0.001 to 0.5,

c may vary from zero to 0.9,

d may vary from zero to 0.9,

with the provisos that c and d both cannot be zero,

and the sum of a+b+c+d≈1,

the polyheterosiloxane composition is soluble in an aromatic hydrocarbon solvent.

2. The polyheterosiloxane composition of claim 1 wherein the first metal M1 is Ti.

3. The polyheterosiloxane composition of claim 2 wherein the second metal M2 is Zn, Zr, or Ba.

4. The polyheterosiloxane composition of claim 1 wherein at least one of the R 1 groups is phenyl.

5. The polyheterosiloxane composition of claim 1 wherein the siloxy units have the formula [(C 6 H 5 )(CH 3 )SiO 2/2 ] c , [(C 6 H 5 )SiO 3/2 ] d , or [(C 6 H 5 )(CH 3 )SiO 2/2 ] c [(C 6 H 5 )SiO 3/2 ] d .

6. A method for preparing the polyheterosiloxane compositions of claim 1 comprising reacting:

(A′) a metal (M1) alkoxide containing Ti, Zr, or Zn,

(B′) a hydrolyzable metal (M2) salt selected from a non-lanthanide metal series of the Periodic Table, provided the metal selected for the second metal M2 is different from the first metal M1, and

(C′) a silicon-containing material having hydrolyzable groups selected from (C′1) an organosiloxane, or (C′2) a silane,

with an amount of water that provides between 50 and 200% necessary to hydrolyze and condense the alkoxy groups and other hydrolyzable groups on Components (A′), (B′), and (C′), to form the present polyheterosiloxane compositions.

7. The method of claim 6 wherein Component (A′) and Component (B′) are reacted with water to form a mixed metal oxides solution containing M1-O-M2 oxo-linkages, and then further reacting the mixed metal oxides solution with Component (C′1) or (C′2) to form the polyheterosiloxane composition, wherein the total amount of water added is between 50 and 200% of the amount theoretically necessary for the hydrolysis and condensation of all alkoxy groups and other hydrolyzable groups on Components (A′), (B′), and (C′).

8. A method for preparing a coating comprising:

I) forming a film of a polyheterosiloxane composition on a surface, wherein the polyheterosiloxane composition comprises at least 70% by weight of:

(A) a first metal (M1) selected from Ti, Zr, or Zn,

(B) a second metal (M2) selected from a non-lanthanide metal, provided the metal selected for the second metal M2 is different from the first metal M1,

(C) siloxy units having the formula R 1 2 SiO 2/2 or R 1 SiO 3/2

where R 1 is independently a hydrocarbon group or halogen substituted

hydrocarbon group containing 1 to 30 carbon atoms,

wherein:

the mole fraction of components (A), (B), and (C) in the polyheterosiloxane composition relative to each other is of the formula [M1] a [M2] b [R 1 2 SiO 2/2 ] c [R 1 SiO 3/2 ] d

where a may vary from 0.10 to 0.7,

b may vary from 0.001 to 0.5,

c may vary from zero to 0.9,

d may vary from zero to 0.9,

with the provisos that c and d both cannot be zero,

and the sum of a+b+c+d≈1,

the polyheterosiloxane composition is soluble in an aromatic hydrocarbon solvent; and

II) heating the film to form a cured coating.

9. A cured coating as prepared by the method of claim 8 .

10. The cured coating of claim 9 wherein the coating has a refractive index≧1.6.

11. The method of claim 8 wherein the first metal M1 is Ti.

12. The method of claim 8 wherein the second metal M2 is Zn, Zr, or Ba.

13. The method of claim 8 wherein at least one of the R 1 groups is phenyl.

14. The method of claim 8 wherein the siloxy units have the formula [(C 6 H 5 )(CH 3 )SiO 2/2 ] c , [(C 6 H 5 )SiO 3/2 ] d , or [(C 6 H 5 )(CH 3 )SiO 2/2 ] c [(C 6 H 5 )SiO 3/2 ] d .

15. The cured coating of claim 9 wherein the first metal M1 is Ti.

16. The cured coating of claim 9 wherein the second metal M2 is Zn, Zr, or Ba.

17. The cured coating of claim 9 wherein at least one of the R 1 groups is phenyl.