PVDF-TrFE co-polymer having improved ferroelectric properties, methods of making a PVDF-TrFE co-polymer having improved ferroelectric properties and methods of changing the end group of a PVDF-TrFE co-polymer
A method of exchanging or transforming end groups in and/or improving the ferroelectric properties of a PVDF-TrFE co-polymer is disclosed. A bulky or chemically dissimilar end group, such as an iodine, sulfate, aldehyde or carboxylic acid end group, may be transformed to a hydrogen, fluorine or chlorine atom. A method of making a PVDF-TrFE co-polymer is disclosed, including polymerizing a mixture of VDF and TrFE using an initiator, and transforming a bulky or chemically dissimilar end group to a hydrogen, fluorine or chlorine atom. A PVDF-TrFE co-polymer or other fluorinated alkene polymer is also disclosed. The co-polymer may be used as a ferroelectric, electromechanical, piezoelectric or dielectric material in an electronic device.
1. A method of exchanging an end group of a polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) co-polymer, comprising:
exchanging an iodine or hydroxyl end group on a polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) co-polymer with hydrogen, fluorine or chlorine, and
isolating or purifying the PVDF-TrFE co-polymer having the hydrogen, fluorine or chlorine end group.
2. The method according to claim 1 , wherein the PVDF-TrFE co-polymer has the iodine end group, and exchanging the iodine end group comprises reacting the PVDF-TrFE co-polymer having the iodine end group with a tin hydride complex.
3. The method according to claim 1 , wherein the PVDF-TrFE co-polymer has the hydroxy end group, and exchanging the hydroxy end group comprises reacting the PVDF-TrFE co-polymer having the hydroxy end group with a source of hydrogen, fluorine or chlorine.
4. The method according to claim 3 , wherein the PVDF-TrFE co-polymer has the hydroxy end group, and exchanging the hydroxy end group comprises reacting the PVDF-TrFE co-polymer having the hydroxy end group with a source of hydrogen.
5. The method according to claim 3 , further comprising converting a PVDF-TrFE, co-polymer having a carboxyl, sulfonyl or sulfate end group to the PVDF-TrFE co-polymer having the hydroxy end group.
6. The method according to claim 5 , wherein converting the PVDF-TrFE co-polymer having the carboxyl, sulfonyl or sulfate end group to the PVDF-TrFE co-polymer having the hydroxy end group comprises hydrolyzing the carboxyl, sulfonyl or sulfate end group.
7. The method according to claim 5 , wherein the carboxyl end group has the formula R 1 —C(═O)O—, the sulfonyl end group has the formula R 2 —S(═O) 2 O—, and the sulfate end group has the formula —OS(═O) 2 O − , where R 1 and R 2 are independently alkyl, aryl, or aralkyl, which may be substituted or unsubstituted.
8. The method according to claim 7 , wherein R 1 and R 2 are independently C 1 -C 6 alkyl, C 6 -C 10 aryl, or C 6 -C 10 aryl substituted with from 1 to 3 methyl groups substituted with 0 to 3 fluorine atoms.