Grafted polymers as oleophobic low adhesion anti-wetting coatings
View Patent ↗An oleophobic grafted polymer includes a crosslinked fluoroelastomer and a perfluorinated polyether grafted to the crosslinked fluoroelastomer. A process for making an oleophobic grafted polymer includes crosslinking a fluoroelastomer with an aminofunctionalized silane and grafting an alkoxysilane-terminated perfluorinated polyether to the crosslinked fluoroelastomer.
1. An oleophobic grafted polymer comprising:
a crosslinked fluoroelastomer; and
a perfluorinated polyether grafted to the crosslinked fluoroelastomer, wherein the fluoroelastomer is crosslinked with an aminofunctionalized silane, the aminofunctionalized silane comprising an aminoalkylsilane-modified polysiloxane.
2. The oleophobic grafted polymer of claim 1 , wherein the aminofunctionalized silane provides graft attachment points.
3. The oleophobic grafted polymer of claim 1 , having a structure of formula I:
wherein FE is a fluoroelastomer;
PFPE is a perfluorinated polyether;
L is a linker;
m, and o are independently an integer from 3 to 8;
n is an integer from 1 to 10;
each incidence of R 1 and R 2 is independently a substituted or unsubstituted C 1 -C 6 alkyl,
R 3 and R 4 are independently an optionally fluorinated C 1 -C 6 alkyl or an optionally fluorinated C 1 -C 6 alkoxy.
4. The oleophobic grafted polymer of claim 3 , wherein the linker L comprises a C 1 -C 6 alkyl terminating in a functional group capable of covalently linking to a terminal hydroxyl functionality group of the perfluorinated polyether.
5. The oleophobic grafted polymer of claim 3 , wherein the fluoroelastomer (FE) is a polymer comprising a monomer unit selected from the group consisting of vinylidene fluoride, tetrafluorethylene, hexafluoropropylene, perfluoromethylvinylether and combinations thereof.
6. The oleophobic grafted polymer of claim 3 , wherein the fluoroelastomer (FE) has a fluorine content of at least about 65 percent.
7. The oleophobic grafted polymer of claim 3 , wherein the fluoroelastomer (FE) has a molecular weight in a range from about 50,000 to about 70,000 daltons as measured by gel permeation chromatography.
8. The oleophobic grafted polymer of claim 3 , wherein the perfluorinated polyether (PFPE) is an alkoxysilane-terminated perfluorinated polyether having an average molecular weight in a range from about 1,500 daltons to about 2,500 daltons.
9. A process for making an oleophobic grafted polymer comprising:
crosslinking a fluoroelastomer with an aminofunctionalized silane; and
grafting perfluorinated polyether to the crosslinked fluoroelastomer, wherein the aminofunctionalized silane comprises an aminoalkylsilane-modified polysiloxane.
10. The process of claim 9 , wherein the oleophobic grafted polymer has a final structure of formula I:
wherein FE is a fluoroelastomer;
PFPE is a perfluorinated polyether;
L is a linker;
m, n, and o are independently an integer from 1 to 10
each incidence of R 1 and R 2 is independently an optionally fluorinated C 1 -C 6 alkyl,
R 3 and R 4 are independently an optionally fluorinated C 1 -C 6 alkyl or an optionally fluorinated C 1 -C 6 alkoxy.
11. The process of claim 9 , wherein the crosslinking step is performed in the presence of the perfluorinated polyether.
12. The process of claim 11 , wherein a ratio of the aminofunctionalized silane to the perfluorinated polyether is in a range from about 0.5:1 to about 3:1.
13. The process of claim 11 , wherein an amount of the aminofunctionalized silane relative to the fluoroelastomer is in a range from about 2 pph to about 10 pph.
14. The process of claim 9 , wherein the fluoroelastomer (FE) is a polymer comprising a monomer unit selected from the group consisting of vinylidene fluoride, tetrafluorethylene, hexafluoropropylene, perfluoromethylvinylether and combinations thereof.
15. The process of claim 9 , wherein the fluoroelastomer (FE) has a fluorine content of at least about 65 percent.
16. The process of claim 9 , wherein the fluoroelastomer (FE) has a molecular weight in a range from about 50,000 to about 70,000 daltons as measured by gel permeation chromatography.
17. The process of claim 9 , wherein the perfluorinated polyether (PFPE) is an alkoxysilane-terminated perfluorinated polyether having an average molecular weight in a range from about 1,500 daltons to about 2,500 daltons.
18. An oleophobic grafted polymer comprising:
a crosslinked fluoroelastomer of structure A:
wherein n is an integer from 1-10;
each of R 1 and R 2 are independently an optionally fluorinated C 1 -C 6 alkyl; and
a perfluorinated polyether grafted to the crosslinked fluoroelastomer;
wherein the OCH 3 groups of the polysiloxane crosslinker provide the reactive site for grafting the perfluorinated polyether.