Properties tailoring in silsesquioxanes
View Patent ↗Fluoride catalyzed rearrangement reactions of polymeric silsesquioxanes [RSiO 1.5 ] n involve reacting at least one silsesquioxane material with a catalytic amount of an organic fluoride at a temperature ranging from about −50° C. to about 120° C. thereby forming a reaction mixture for a period ranging from 60 minutes to 48 hours. To the reaction mixture, a quenching agent is added to remove fluoride from the reaction mixture. A silsesquioxane cage compound can be isolated from the reaction mixture using a precipitation or other extraction process.
1. A method for making a silsesquioxane cage compound by depolymerization of a polysilsesquioxane comprising:
a) reacting at least one polysilsesquioxane with a catalytic amount of an organic cationic fluoride at a temperature ranging from about −50° C. to about 120° C. in an organic solvent thereby forming a liquid reaction mixture, wherein the organic cationic fluoride is present in a catalytic amount of 50 mole % or less, based on the polysilsesquioxane;
b) adding a quenching agent to the liquid reaction mixture to remove fluoride from the reaction mixture; and
c) isolating a silsesquioxane cage compound from the reaction mixture by precipitation or by solvent removal.
2. A method according to claim 1 , wherein the fluoride is provided in the liquid reaction mixture at a level of 0.1-10 mole %, based on moles of silsesquioxane.
3. A method according to claim 2 , wherein the amount of fluoride is 0.5-10 mole %.
4. A method according to claim 2 , wherein the level of fluoride is 0.5-5 mole %.
5. A method according to claim 1 , comprising reacting at a temperature of 0-100° C.
6. A method according to claim 1 , comprising reacting at a temperature of 10-50° C.
7. A method according to claim 1 , wherein the quenching agent comprises a calcium salt.
8. A method according to claim 7 , wherein the quenching agent comprises calcium chloride.
9. A method according to claim 1 , comprising mixing at a temperature of 10-50° C.
10. A method for synthesizing a random structure polysilsesquioxane T resin from a single or mixed polymeric silsesquioxane cage compound, the method comprising:
a) combining one or more silsesquioxane cage compounds with an organic solvent and a catalytic amount of a source of organic fluoride ion, thereby forming a first mixture, wherein the organic fluoride ion is present in an amount of 50 mole % or less, based on the silsesquioxane cage compounds;
b) mixing the first mixture for a time and at a temperature to make a reaction mixture comprising the T resin; and
c) isolating the T resin polymer by removal of said organic solvent.
11. A method according to claim 10 , wherein the catalytic amount of a source of organic fluoride ion comprises 0.1-10 mole % of fluoride, based on total moles of silsesquioxane.
12. A method according to claim 11 , wherein the catalytic amount is 0.5-10 mole %.
13. A method according to claim 11 , wherein the catalytic amount is 0.5-5 mole %.
14. A method according to claim 10 , comprising mixing at a temperature of 20-30° C.
15. A method according to claim 10 , wherein the one or more cage compound is selected from the group consisting of T 8 , T 10 , or T 12 structures characterized by formula [RSiO 1.5 ] n , where n=8, 10, or 12 and wherein the R groups are independently selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, alkenylaryl, alkylaryl, arylalkyl, and arylalkenyl.
16. A process for making a T 8 , T 10 , T 12 , or T 14 silsesquioxane mixed cage compound with a structure represented by [R 2 x R 1 n-x SiO 1.5 ] n wherein n is 8, 10, 12, or 14 and x is 1-13, R 1 is a first organic group, and R 2 is a second organic group, the process comprising,
a. adding a catalytic amount of organic fluoride ion to a mixture of starting cage structures [R 2 n SiO 1.5 ] n and [R 1 n SiO 1.5 ] n to make a first mixture, wherein the catalytic amount of organic fluoride ion is 50 mole % or less, based on the starting cage structures; and
b. reacting the starting cage structures in the presence of fluoride ion to form a reaction mixture comprising the mixed cage compounds.
17. A method of process according to claim 16 , comprising providing [R 2 n SiO 1.5 ] n and [R 1 n SiO 1.5 ] n in the first mixture in a molar ratio such that x is predominantly 1, 2, or 3 in the reaction product [R 2 x R 1 n-x SiO 1.5 ] n .
18. A process according to claim 17 , wherein one of R 1 and R 2 is vinyl.
19. A process according to claim 16 , comprising reacting at a temperature of 10-50° C.
20. A process according to claim 16 , comprising reacting at a temperature of 20-30° C.
21. A process according to claim 16 , comprising reacting in the presence of 0.1-10 mole % fluoride ion, based on moles of silsesquioxane.
22. A process according to claim 21 , comprising reacting in the presence of 0.5-5 mole % fluoride ion.
23. A process according to claim 21 , comprising reacting in the presence of 0.1-2 mole % fluoride ion in the form of tetraalkylammonium fluoride.
24. A process according to claim 16 , further comprising quenching the reaction mixture to remove fluoride, then isolating the T 8 , T 10 , or T 12 and/or T 14 cage compounds by precipitation or solvent removal.
25. A process according to claim 24 , comprising quenching with a molar excess of quenching agent that preferentially reacts with fluoride ion.
26. A process according to claim 25 , wherein the quenching agent is a calcium salt.
27. A process according to claim 25 , wherein the quenching agent is calcium chloride.