Branched polyorganosiloxanes and related curable compositions, methods, uses, and devices

1. A radical-curable branched polyorganosiloxane of formula:

(SiO 4/2 ) m (R 1 SiO 3/2 ) n (R 1 2 SiO 2/2 ) o (R 2 R 1 SiO 2/2 ) p (R 2 R 1 2 SiO 1/2 ) q (R 1 3 SiO 1/2 ) r (R 3 ) s

wherein:

each R 1 is independently a monovalent organic group free of aliphatic unsaturation;

each R 2 is independently a radical-curable group;

each R 3 is independently an alkylene having 2 to 12 carbon atoms;

subscript m is 1;

subscript n is 0;

subscript o is from 100 to 1100;

subscript p is 0;

subscript q is from 2.9 to 4;

and

subscript r is from 0 to 1.1;

with the proviso that the sum of subscripts q+r=n+2m+2;

subscript s is from 2 to 6;

and

wherein the branched polyorganosiloxane has, on average, at least 2 radical-curable groups (i.e. R 2 ) per molecule.

2. The branched polyorganosiloxane of claim 1 , wherein each radical-curable group is independently a monovalent organic group containing an acrylate group, a methacrylate group, or a combination thereof.

3. The branched polyorganosiloxane of claim 1 that is a reaction product of a reaction of constituents comprising:

(a) a branched polyorganosiloxane having, on average, greater than two silicon bonded hydrogen atoms per molecule; and

(b) a reactive species having, per molecule, at least one aliphatically unsaturated organic group and one or more radical-curable groups selected from acrylate groups and methacrylate groups;

in the presence of

(c) a hydrosilylation catalyst.

4. The branched polyorganosiloxane of claim 1 that is a reaction product of a reaction of constituents comprising:

(a′) a branched polyorganosiloxane having, on average, greater than two aliphatically unsaturated groups per molecule; and

(b′) a reactive species having, per molecule, at least one silicon-bonded hydrogen and one or more radical-curable groups selected from acrylate groups and methacrylate groups,

in the presence of

(c) a hydrosilylation catalyst.

5. A curable silicone composition comprising:

(I) a radical-curable branched polyorganosiloxane of formula:

(SiO 4/2 ) m (R 1 SiO 3/2 ) n (R 1 2 SiO 2/2 ) o (R 2 R 1 SiO 2/2 ) p (R 2 R 1 2 SiO 1/2 ) q (R 1 3 SiO 1/2 ) r (R 3 ) s

wherein

each R 1 is independently a monovalent organic group free of aliphatic unsaturation;

each R 2 is independently a radical-curable group;

each R 3 is independently an alkylene having 2 to 12 carbon atoms;

subscript m is 1;

subscript n is 0;

subscript o is from 100 to 1100;

subscript p is 0;

subscript q is from 2.9 to 4;

subscript r is from 0 to 1.1;

with the proviso that the sum of subscripts q+r=n+2m+2;

subscript s is from 2 to 6;

wherein the radical-curable branched polyorganosiloxane (I) has, on average, at least 2 radical-curable groups per molecule; and

(II) a radical initiator.

6. The curable silicone composition of claim 5 wherein R 2 is a monovalent organic group containing an acrylate group, a methacrylate group, or a combination thereof.

7. The curable silicone composition of claim 5 , wherein the radical-curable branched polyorganosiloxane (I) comprises a reaction product of a reaction of constituents comprising:

(a) a branched polyorganosiloxane having, on average, greater than two silicon bonded hydrogen atoms per molecule; and

(b) a reactive species having, per molecule, at least one aliphatically unsaturated organic group and one or more radical-curable groups selected from acrylate groups and methacrylate groups;

in the presence of

(c) a hydrosilylation catalyst.

8. The curable silicone composition of claim 7 wherein constituent (a) comprises a reaction product of a reaction of constituents comprising:

(a1) a branched polyorganosiloxane having on average, per molecule, greater than two aliphatically unsaturated groups; with

(a2) a polyorganosiloxane having two silicon bonded hydrogen atoms;

in the presence of

(c) a hydrosilation catalyst.

9. The curable silicone composition of claim 5 , wherein the radical-curable branched polyorganosiloxane (I) comprises a reaction product of a reaction of constituents comprising:

(a′) a branched polyorganosiloxane having, on average, greater than two aliphatically unsaturated groups per molecule; and

(b′) a reactive species having, per molecule, at least one silicon-bonded hydrogen and one or more radical-curable groups selected from acrylate groups and methacrylate groups, in the presence of

(c) a hydrosilylation catalyst.

10. The curable silicone composition of claim 9 wherein the reactive species (b′) is of formula: R 5 j SiR 2 k R 1 (4−j−k) , wherein

each of subscripts j and k independently is from 1 to 3 with the proviso that the sum of subscripts (j+k) is less than or equal to 4;

each R 5 is independently a hydrogen atom or a monovalent organosilicon group containing a silicon bonded hydrogen atom;

each R 2 is independently a radical-curable group; and

each R 1 is independently a monovalent organic group free of aliphatic unsaturation.

11. The curable silicone composition of claim 5 further comprising (IV) a filler; (V) a filler treating agent; or both (IV) and (V).

12. The curable silicone composition of claim 5 further comprising (VI) a moisture cure initiator and (VII) a crosslinker.

13. A method for making a cured article, the method comprising applying the curable silicone composition of claim 5 to a substrate; and curing the applied curable silicone composition onto the substrate.

14. A cured product of curing the curable silicone composition of claim 5 .

15. An electronic device comprising the cured product of claim 14 and at least one other device component in operative contact therewith.

16. A manufactured article comprising a substrate and a sealant disposed in sealing operative contact thereon, the sealant comprising the cured product of claim 14 .

17. A manufactured article comprising an assembly comprising first and second substrates and an adhesive disposed in adhering operative contact therebetween, the adhesive comprising the cured product of claim 14 .

18. A device comprising a thermally conductive member and at least one other component in thermal communication therewith, the thermally conductive member comprising the cured product of claim 14 .