Reactive polyorganosiloxanes having controlled molecular weight and functionality
View Patent ↗The present invention relates to photoradiation and/or moisture curing silicone compositions and methods for producing and using the same. In particular, the methods of the present invention permit controlled growth of a polymer, and allow for incorporation of pendant functional groups along the length of the polymer.
1. A photoradiation and/or moisture curing composition, comprising
wherein
m is 10-2000;
n is 10-2000;
R in each occurrence can be the same or different and is a member selected from the group consisting of H and C 1 -C 3 alkyl;
R 1 is a member selected from the group consisting of H and C 1 -C 3 alkyl;
R 2 is a member selected from the group consisting of H and C 1 -C 3 alkyl;
R 3 is
—Si(OR 1 )(OR 2 )-A-Y;
A is C 1 -C 3 alkylene; and
Y at each occurrence is either the same or different, and is a group capable of free radical polymerization and containing at least one of: an unsaturated double bond; an epoxide ring; or an episulfide ring.
2. The composition of claim 1 , wherein Y is selected from the group consisting of epoxy, vinyl, alkylvinyl, acryloxy, alkylacryloxy, allylic, alkylallylic, alkynyl, alkylalkynyl, and azo.
3. The composition of claim 1 , wherein the compound has the formula
4. The composition of claim 1 , further comprising a photoinitiator.
5. The composition of claim 1 , further comprising a moisture-cure catalyst.
6. The composition of claim 1 , further comprising a hydroquinone stabilizer.
7. A photoradiation and/or moisture curing silicone composition comprising the product of:
a) at least one siloxane having the formula:
wherein
n is 10-2000; and
R is C 1 -C 3 alkyl; and
b) a silane having the formula
wherein
R 1 is a member selected from the group consisting of H and C 1 -C 3 alkyl;
R 2 is a member selected from the group consisting of H and C 1 -C 3 alkyl;
A is C 1 -C 3 alkylene; and
Y is a group capable of free radical polymerization and containing at least one of: an unsaturated double bond; an epoxide ring; or an episulfide ring; and
wherein the total amount of silane exposed to the siloxane is less than one molar equivalent.
8. The reaction product of claim 7 , wherein
R is methyl;
R 1 is methyl or ethyl;
R 2 is methyl or ethyl;
A is methylene; and
Y is methacryloxy.
9. The composition of claim 7 , wherein the siloxane of a) and the silane of b) react in the presence of an appropriate base.
10. The composition of claim 9 , wherein the appropriate base is butyl lithium.
11. A process for preparing the composition of claim 1 , comprising the steps of:
a) reacting in the presence of a base at least one siloxane having the formula
wherein
R is C 1 -C 3 alkyl;
and
n is 10-2000;
b) with a silane having the formula
wherein
R 1 is a member selected from the group consisting of H and C 1 -C 3 alkyl;
R 2 is a member selected from the group consisting of H and C 1 -C 3 alkyl;
A is C 1 -C 3 alkylene; and
Y is a group capable of free radical polymerization and containing at least one of: an unsaturated double bond; an epoxide ring; or an episulfide ring; and
wherein the total amount of silane exposed to the siloxane is less than one molar equivalent.
12. The process of claim 11 , wherein
R is methyl;
R 1 is methyl or ethyl;
R 2 is methyl or ethyl;
A is methylene; and
Y is methacryloxy.
13. The process of claim 11 , wherein step a) comprises reacting at least two of said siloxanes, wherein said siloxanes have different molecular weights.
14. The reaction product of the composition of claim 5 .
15. The reaction product of the composition of claim 1 upon exposure to photoradiation.
16. The reaction product of claim 1 upon exposure to moisture.
17. A method of controlling the molecular weight and/or the inclusion of functional groups in the formation of a reactive polyorganosiloxane composition comprising the steps of:
a) selecting an approximate desired molecular weight of the reactive polyorganosiloxane composition to be made;
b) providing a hydroxy-terminated polyalkylsiloxane of desired molecular weight;
c) providing a trialkoxy C 1 -C 3 alkylsilane in an amount less than one molar equivalent; and
d) reacting the hydroxy-terminated polyalkylsiloxane of step b) with the trialkoxy C 1 -C 3 alkylsilane of step c) for a time sufficient to form a chain extended reactive polymer having pendant functional groups along the polymer backbone, wherein the total amount of silane exposed to the hydroxy-terminated polyalkylsiloxane is less than one molar equivalent and wherein the resulting reactive polyorganosiloxane composition has at least one of: (i) the desired molecular weight; or (ii) the desired functional groups.
18. A method for using composition of claim 1 to join or seal two substrates comprising the steps of:
a) applying the composition to at least one of two substrate surfaces;
b) mating the two substrate surfaces in an abutting relationship to form an assembly;
c) exposing the composition to moisture and/or photoradiation; and
d) maintaining the abutting relationship for a time sufficient to allow the composition to cure.
19. A method of controlling the viscosity of a reactive polyorganosiloxane composition comprising the steps of:
a) selecting an approximate desired viscosity of the reactive polyorganosiloxane composition to be made;
b) providing a hydroxy-terminated polyalkylsiloxane;
c) providing a trialkoxy C 1 -C 3 alkylsilane in an amount less than one molar equivalent; and
d) reacting the hydroxy-terminated polyalkylsiloxane of step b) with the trialkoxy C 1 -C 3 alkylsilane of step c) for a time sufficient to form a chain extended reactive polymer having pendant functional groups along the polymer backbone, wherein the total amount of silane exposed to the hydroxy-terminated polyalkylsiloxane is less than one molar equivalent and wherein the resulting reactive polyorganosiloxane composition has the desired viscosity.