Electrocaloric polymer, ink and film comprising same, and uses thereof
A polymer including VDF-based units having an electrocaloric effect under the effect of a variable electric field. The polymer includes 0.1 to 10.0 mol % double bonds, which are substantially non-conjugated. Also, a corresponding composition including the polymer, a corresponding film including the polymer, and to various uses of the polymer.
1 . A polymer exhibiting an electrocaloric effect under the effect of a variable electric field, said polymer comprising:
from 30 mol % to 90 mol % of unit of formula: -(CF2-CH2)-(III),
from 1 mol % to 59.9 mol % of at least one unit of formula: -(CX1X2-CX3X4)-(IV),
from 0 mol % to (20-N) mol % of at least one unit of formula: -(CY1Y2-CY3Z)—(V),
N mol % of ethylenic unit(s) chosen from the list consisting of: —(CY3═CF)—, —(CY3═CX1)-, -(CY3═CX2)-, -(CY1═CY3)-, -(CY2═CY3)- and their mixture;
in which:
X1 and X2 independently denote: —H, —F or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated,
X3 and X4 independently denote: —F or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated, except for the combination where:
X1 and X2 are both: —H and X3 and X4 are both: —F,
Y1 and Y2 independently denote: —H, —F, —CI or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated,
Y3 denotes: —F, —Cl or alkyl groups comprising from 1 to 3 carbon atoms which are optionally partially or completely fluorinated,
Z denotes a halogen atom other than: —F,
N is a number ranging from 0.1 to 10.0;
said polymer essentially not exhibiting a conjugated carbon-carbon double bond.
2 . The polymer as claimed in claim 1 , in which X1 denotes: —H or —F; and X2, X3 and X4 denote, all three: —F.
3 . The polymer as claimed in claim 1 , in which Z denotes: —Cl.
4 . The polymer as claimed in claim 1 , in which Y3 denotes: —F, and Y1 and Y2 both denote: —H or —F.
5 . The polymer as claimed in claim 1 , said polymer comprising at least 1 mol % of unit of formula (V).
6 . The polymer as claimed in claim 1 , said polymer being relaxor ferroelectric.
7 . The polymer as claimed in claim 1 , said polymer having a remanent polarization of less than or equal to 20 mC/m2 and/or a coercive field of less than or equal to 25 V·μm−1,
the remanent polarization and coercive field measurements both being carried out at 25° C., at a frequency of 1 Hz and at a field of 150 V/μm.
8 . The polymer as claimed in claim 1 , having a weight-average molecular weight of greater than or equal to 200 000 g/mol.
9 . The polymer as claimed in claim 1 , having an enthalpy of fusion of greater than or equal to 10 J/g,
the enthalpy of fusion being measured according to the standard ISO 11357-2: 2013, in second heating with temperature gradients of 10° C./min.
10 . The polymer as claimed in claim 1 , having a relative dielectric permittivity of greater than or equal to 15, over a range of temperatures of at least 5° C. said relative dielectric permittivity being measured at 1 kHz.
11 . The polymer as claimed in claim 1 , having a permittivity maximum at a temperature of less than or equal to 60° C.;
said relative dielectric permittivity being measured at 1 kHz.
12 . The polymer as claimed in claim 1 , said polymer being capable of being obtained by a process comprising:
a) the provision of an initial polymer comprising, in total moles of polymer:
from 40 mol % to 90 mol % of unit of formula: —(CF2-CH2)-(III),
from 9.9 mol % to 59.9 mol % of at least one unit of formula: —(CX1X2-CX3X4)-(IV),
from 0.1 mol % to 20 mol % of at least one unit of formula: —(CY1Y2-CY 3 Z)— (V);
b) the dehydrohalogenation of said initial polymer, said dehydrohalogenation consisting essentially of the elimination, at least partially, of: —Z and of an adjacent hydrogen.
13 . The polymer as claimed in claim 10 , having a variation in adiabatic temperature which is at least greater by 0.5° C., with respect to the variation in adiabatic temperature of said initial polymer, at at least one measurement temperature, the measurements of variations in adiabatic temperatures being carried out at a variable electric field having a maximum amplitude equal to 86 V/μm.
14 . The polymer as claimed in claim 12 , having a relative dielectric permittivity maximum which is at least greater by 5%, with respect to the dielectric permittivity maximum of said initial polymer;
said relative dielectric permittivity being measured at 1 kHz.
15 . The polymer as claimed in claim 12 , in which the dehydrohalogenation is carried out with a reaction progress of at least 0.1.
16 . A composition comprising: at least one polymer as claimed in claim 1 , and at least one liquid vehicle for said polymer.
17 . A film comprising the polymer as claimed in claim 1 .
18 . The film as claimed in claim 17 , having a thickness of greater than or equal to 0.1 micrometer.
19 . A heat transfer system comprising a polymer as claimed in claim 1 .
20 . An energy storage system comprising a polymer as claimed in claim 21 .
21 . The polymer as claimed in claim 1 , in which X1 denotes: —H; X2, X3 and X4 denote, all three: —F; Y3 denotes: —F; Y1 and Y2 both denote: —H; and Z denotes —Cl;
in which N is chosen between 0.1 and 2.
22 . The polymer as claimed in claim 1 , in which X1 denotes: —H; X2, X3 and X4 denote, all three: —F; Y1, Y2 and Y3 denote, all three: —F; and Z denotes: —Cl;
in which N is chosen between 0.1 and 10.0.