Nanostructured organosilicates from thermally curable block copolymers
View Patent ↗Provided are inorganic-organic block copolymers that self assemble without the addition of a precursor. The inorganic block of the polymers includes silicon and the organic block may be any organic polymer. The inorganic-organic block copolymers self assemble to form a material in which the inorganic polymer block may be crosslinked to produce an organosilicate and/or silica matrix, and further thermal curing of the matrix results in the formation of a porous nanostructured film.
1. A method of preparing a nanostructured organosilicate matrix comprising the steps of:
(a) preparing a self-assembled material from a block copolymer comprising (i) at least one of an alpha-, beta-, and gamma-substituted polysiloxane polymer block, and (ii) an organic polymer block, wherein the polysiloxane polymer block directly transforms into an organosilicate and/or silica matrix comprising an inorganic domain and an organic domain; and
(b) curing the self-assembled material at a temperature in the range of 20° C. to 450° C. to crosslink the inorganic domain to form a nanostructured organosilicate matrix.
2. The method of claim 1 , wherein the self-assembled material of step (b) is cured at a temperature in the range of 50° C. to 300° C.
3. The method of claim 1 , wherein the self-assembled material of step (b) is cured at a temperature in the range of 20° C. to 120° C. in the presence of an acid catalyst.
4. The method of claim 1 , further comprising the step of:
(c) curing the nanostructured matrix of step (b) at a temperature in the range of 300° C. to 500° C. for approximately 1 h to form a porous nanostructured film.
5. The method of claim 1 , wherein the organic polymer block is selected from the group consisting of acrylate polymers, methacrylate polymers, poly(alkylenes), poly(butadienes), poly(carbonates), poly(esters), poly(lactides), poly(isoprenes), poly(norbornenes), poly(styrenes), and substituted poly(styrenes).
6. The method of claim 5 , wherein the polysiloxane polymer block comprises a monomer repeat unit selected from the group consisting of structure (I) and structure (II):
wherein
R 1 is independently alkylene;
R 2 is selected from the group consisting of C1-C20 alkyl, cycloalkyl, aryl, and aromatic;
and X is independently an electronegative group.
7. The method of claim 6 , wherein
R 1 is independently selected from the group consisting of methylene, ethylene, and propylene;
R 2 is selected from the group consisting of methyl and ethyl; and
X is independently selected from the group consisting of acetoxy, substituted acetoxy, thioacetoxy, substituted thioacetoxy, benzoyl, substituted benzoyl, bromine, chlorine, and iodine.
8. The method of claim 5 , wherein the polysiloxane polymer block comprises a monomer repeat unit selected from the group consisting of structure (III) and structure (IV):
wherein
R 3 is selected from the group consisting of C1-C20 alkyl, cycloalkyl, aryl, and aromatic; and
R 4 is independently selected from the group consisting of C1-C20 alkyl, cycloalkyl, aryl, hydroxy alkyl, alkylamine, alkylamide, and alkylurea.
9. The method of claim 8 , wherein
R 3 is selected from the group consisting of methyl and ethyl; and
R 4 is independently selected from the group consisting of hydroxyethylthioethyl, carboxyethylthioethyl, and ethylureaethylthioethyl.
10. The method of claim 5 , wherein the polysiloxane polymer block comprises a monomer repeat unit selected from the group consisting structure (V) and structure (VI):
wherein R 5 is selected from the group consisting of alkyl, cycloalkyl, aryl, and aromatic.
11. The method of claim 10 , wherein R 5 is selected from the group consisting of methyl and ethyl.
12. The method of claim 5 , wherein the polysiloxane polymer block comprises a monomer repeat unit selected from the group consisting of structure (VII) and structure (VIII):
wherein R 6 is selected from the group consisting of alkyl, cycloalkyl, aryl, and aromatic.
13. The method of claim 12 , wherein R 6 is selected from the group consisting of methyl and ethyl.
14. The method of claim 1 , wherein the polysiloxane polymer block is selected from the group consisting of poly(methyl acetoxyethyl)siloxane); poly(methyl thioacetoxyethylsiloxane); poly(methyl hydroxyethylthioethylsiloxane); poly(methyl carboxyethylthioethylsiloxane); poly(methyl ethylureaethylthioethylsiloxane); poly(methyl oxiranylsiloxane); and poly(methyl 1,2-dihydroxyethylsiloxane).
15. The method of claim 1 , wherein the self-assembling block copolymer further comprises a photoacid generator (PAG).
16. The method of claim 15 , wherein the PAG is selected from the group consisting of triphenylsulfonium nonaflate; (trifluoro-methylsulfonyloxy)-bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide (MDT); N-hydroxy-naphthalimide (DDSN); onium salts; benzoin tosylate; t-butylphenyl α-(p-toluenesulfonyloxy)-acetate; t-butyl α-(p-toluenesulfonyloxy)-acetate; sulfonic acid esters of N-hydroxyamides, imides, or combinations thereof; nitrobenzyl esters; s-triazine derivatives; N-camphorsulfonyloxynaphthalimide; N-pentafluorophenylsulfonyloxynaphthalimide; ionic iodonium sulfonates; perfluoroalkanesulfonates; aryl triflates; pyrogallol derivatives; trifluoromethanesulfonate esters of hydroxyimides; α,α′-bis-sulfonyl-diazomethanes; sulfonate esters of nitro-substituted benzyl alcohols; naphthoquinone-4-diazides; and alkyl disulfones.
17. The method of claim 16 , wherein the block copolymer is irradiated after step (a) to form an acid.
18. A composition comprising a block copolymer comprising a polysiloxane-containing inorganic polymer block and an organic polymer block, wherein the polysiloxane-containing inorganic polymer block comprises a monomer repeat unit selected from the group consisting of structure (I) and structure (II):
wherein
R 1 is independently alkylene;
R 2 is selected from the group consisting of C1-C20 alkyl, cycloalkyl, aryl, and aromatic; and
X is independently an electronegative group.
19. The composition of claim 18 , wherein
R 1 is independently selected from the group consisting of methylene, ethylene, and propylene;
R 2 is selected from the group consisting of methyl and ethyl; and
X is independently selected from the group consisting of acetoxy, substituted acetoxy, thioacetoxy, substituted thioacetoxy, benzoyl, substituted benzoyl, bromine, chlorine, and iodine.
20. A composition comprising a block copolymer comprising a polysiloxane-containing inorganic polymer block and an organic polymer block, wherein the polysiloxane-containing inorganic polymer block comprises a monomer repeat unit selected from the group consisting of structure (III) and structure (IV):
wherein
R 3 is selected from the group consisting of C1-C20 alkyl, cycloalkyl, aryl, and aromatic; and
R 4 is independently selected from C1-C20 alkyl, cycloalkyl, aryl, hydroxy alkyl, alkylamine, alkylamide, and alkylurea.
21. The composition of claim 20 , wherein
R 3 is selected from the group consisting of methyl and ethyl; and
R 4 is independently selected from the group consisting of hydroxyethylthioethyl, carboxyethylthioethyl, and ethylureaethylthioethyl.
22. A composition comprising a block copolymer comprising a polysiloxane-containing inorganic polymer block and an organic polymer block, wherein the polysiloxane-containing inorganic polymer block comprises a monomer repeat unit selected from the group consisting of structure (V) and structure (VI):
wherein R 5 is selected from the group consisting of alkyl, cycloalkyl, aryl, and aromatic.
23. The composition of claim 22 , wherein R 5 is selected from the group consisting of methyl and ethyl.
24. A composition comprising a block copolymer comprising a polysiloxane-containing inorganic polymer block and an organic polymer block, wherein the polysiloxane-containing inorganic polymer block comprises a monomer repeat unit selected from the group consisting of structure (VII) and structure (VIII):
wherein R 6 is selected from the group consisting of alkyl, cycloalkyl, aryl, and aromatic.
25. The composition of claim 24 , wherein R 6 is selected from the group consisting of methyl and ethyl.