Silicone based nanocomposites including inorganic nanoparticles and their methods of manufacture and use
Silicone-based nanocomposites that include a plurality of multimodal nanoparticles dispersed within a silicone-based polymeric matrix are provided. Each of the multimodal nanoparticle has a first plurality of long silicone compatible polymeric chains and a second plurality of short silicone compatible polymeric chains grafted onto a surface of a nanoparticle (e.g., an inorganic nanoparticle, such as silica, alumina, titania, indium tin oxide, CdSe, etc.), with the short silicone compatible polymeric chains present on each multimodal nanoparticle at a higher grafting density than the long silicone compatible polymeric chains. Methods are also provided for forming a silicone-based nanocomposite.
1. A silicone-based nanocomposite comprising a plurality of multimodal nanoparticles dispersed within a silicone-based polymeric matrix, wherein each multimodal nanoparticle comprises a first plurality of long silicone compatible polymeric chains and a second plurality of short silicone compatible polymeric chains grafted onto a surface of a nanoparticle, and wherein the short silicone compatible polymeric chains are present on each multimodal nanoparticle at a higher grafting density than the long silicone compatible polymeric chains.
2. The silicone-based nanocomposite as in claim 1 , wherein the multimodal nanoparticles form agglomerations having an average size that is less than about 400 nm.
3. The silicone-based nanocomposite as in claim 1 , wherein the multimodal nanoparticles form agglomerations having an average size that is less than about 40 nm.
4. The silicone-based nanocomposite as claim 1 , wherein the silicone-based nanocomposite displays a transparency of 90% or more in at least part of the visible spectrum.
5. The silicone-based nanocomposite as claim 1 , wherein the short silicone compatible polymeric chains have a molecular weight of about 2,500 g/mol to about 25,000 g/mol.
6. The silicone-based nanocomposite as claim 1 , wherein the long silicone compatible polymeric chains have a molecular weight of about 25,000 g/mol to about 250,000 g/mol.
7. The silicone-based nanocomposite as claim 1 , wherein the short silicone compatible polymeric chains comprise a polydimethylsiloxane chain covalently linked to the surface of the nanoparticle via a phosphorus linkage.
8. The silicone-based nanocomposite as in claim 7 , wherein the phosphorus linkage is a phosphate linkage.
9. The silicone-based nanocomposite as in claim 7 , wherein the phosphorus linkage is a phosphono linkage.
10. The silicone-based nanocomposite as claim 1 , wherein the long silicone compatible polymeric chains comprise a polydimethylsiloxane chain covalently linked to the surface of the nanoparticle via a phosphorus linkage.
11. The silicone-based nanocomposite as claim 1 , wherein the nanoparticles comprise inorganic nanoparticles.
12. The silicone-based nanocomposite as in claim 11 , wherein the inorganic nanoparticles comprise silica, alumina, titania, indium tin oxide, CdSe, or mixtures thereof.
13. The silicone-based nanocomposite as claim 1 , wherein the long silicone compatible polymeric chains are linked to the surface of the nanoparticle in two locations.
14. The silicone-based nanocomposite as claim 1 , wherein the long silicone compatible polymeric chains define branched polymeric chains.
15. The silicone-based nanocomposite as claim 1 , wherein the long silicone compatible polymeric chains are linked to the surface of the nanoparticle at more than two locations.
16. A method of forming a silicone-based nanocomposite, the method comprising:
dispersing nanoparticles within a solvent containing a surfactant, wherein each nanoparticle defines a surface;
grafting long silicone compatible polymeric chains onto the surfaces of nanoparticles;
grafting short silicone compatible polymeric chains onto the surface of nanoparticles such that each nanoparticle has a first plurality of the long silicone compatible polymeric chains and a second plurality of short silicone compatible polymeric chains grafted onto its surface to form a multimodal nanoparticle, wherein the short silicone compatible polymeric chains are present on each multimodal nanoparticle at a higher grafting density than the long silicone compatible polymeric chains; and
dispersing the multimodal nanoparticles within a silicone polymeric matrix to form a silicone-based nanocomposite.
17. The method as in claim 16 , wherein the long silicone compatible polymeric chains are grafted onto the surfaces of the nanoparticles prior to the short silicone compatible polymeric chains.
18. The method as in claim 16 , wherein the long silicone compatible polymeric chain grafted to the surface of the nanoparticle comprises:
where:
n is greater than about 2,000;
R 1 is a covalent bond, an oxygen linkage, an organic linkage, an amine linkage, or a sulfide linkage;
R 2 and R 3 are, independently, H, an organic group, or an amine group;
R 4 is a functional or non-functional end group; and
R 5 and R 6 are, independently, H or an organic group.
19. The method as in claim 18 , wherein the short silicone compatible polymeric chain grafted to the surface of the nanoparticle comprises:
where
m is less than n;
R 1 is a covalent bond, an oxygen linkage, an organic linkage, an amine linkage, or a sulfide linkage;
R 2 and R 3 are, independently, H, an organic group, or an amine group;
R 4 is a non-functional end group; and
R 5 and R 6 are, independently, H or an organic group.
20. The method as in claim 19 , wherein R 4 is an alkane group.
21. The method as in claim 16 , wherein the long silicone compatible polymeric chain grafted to the surface of the nanoparticle comprises:
where:
n is greater than about 2,000;
R 1 and R 4 are, independently, a covalent bond, an oxygen linkage, an organic linkage, an amine linkage, or a sulfide linkage;
R 2 and R 3 are, independently, H, an organic group, or an amine group; and
R 5 , R 6 , R 7 , and R 8 are, independently, H or an organic group.