Formulations based on electroactive fluoropolymers for actuators
The present invention relates to compositions obtained by mixing specific electroactive fluoro-terpolymers and specific electroactive fluorinated copolymers. The invention also concerns liquid formulations (inks) that can be used through conventional processing technologies for printed electronics and microelectronics in a safe environment, based on these compositions. Another aspect of this invention are the films manufactured using these formulations, and the devices comprising at least one layer of these films.
1. An electroactive fluoropolymer composition consisting of:
a) an electroactive terpolymer of formula P (VDF-TrFE-X) comprising monomer units of vinylidene fluoride (VDF), of trifluoroethylene (TrFE) and of a third monomer X, X being 1-chloro-1-fluoroethylene (CFE), the molar proportion of X units in the terpolymer being inferior or equal to 3.8%, and
b) an electroactive copolymer of formula P (VDF-TrFE) comprising monomer units of vinylidene fluoride and of trifluoroethylene, the molar proportion of TrFE units in the copolymer being at least 45%.
2. The composition of claim 1 , in which the electroactive terpolymer has a molar ratio VDF/(VDF+TrFE) in the range of 15 to 60%.
3. The composition of claim 1 , wherein the mass ratio of electroactive terpolymer in the composition is superior to 50%.
4. A liquid formulation of electroactive fluoropolymers comprising the composition according to claim 1 , in a solvent.
5. The formulation of claim 4 in which said solvent is selected from the group of ketones, dimethylformamide, dimethyl acetamide, dimethyl sulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and cyclopentanone, furans, tetrahydrofuran; esters, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, glycol ethers and glycol ether esters, propylene glycol methyl ether acetate; carbonates, dimethylcarbonate; phosphates, triethylphosphate, dimethylsulfoxide; or their mixtures.
6. The formulation of claim 4 also comprising an additive selected from the group of: wetting agents, viscosity modifiers, adhesion modifiers and crosslinking agents.
7. Film obtained from the formulation of claim 4 .
8. Film according to claim 7 , having elastic modulus at room temperature above 500 MPa, wherein the film is in an unstretched state.
9. Film according to claim 7 , wherein said film presents a deformation, upon an applied field of 110 V/μm, above 0.1%.
10. Film according to claim 7 , prepared by a solvent cast process.
11. An electromechanical device comprising at least one layer of the film according to claim 7 .
12. An actuator comprising at least one layer of the film according to claim 7 .
13. An acoustic device, said acoustic device comprising at least one layer of the film according to claim 7 .
14. A microelectromechanical system (MEMS) comprising at least one layer of the film according to claim 7 .
15. An (opto)electronic device comprising at least one layer of the film according to claim 7 .