Intellectual Property Office
Non-Confidential Disclosures
“Semicrystalline Ferroelectric Fluoropolymers for Electromechanical Applications”
PSU Invention Disclosure No. 2282
Key Words:
Ferroelectrics; actuators; transducers
Links:
US Patent 6,355,749
http://www.matse.psu.edu/fac/profiles/chung.htm
http://www.ipo.psu.edu
Inventors:
T.C. (Mike) Chung, A. Petchsuk
Background:
Ferroelectric materials that generate mechanical actuation induced by external electric field have attracted a great deal of attention and have been recognized for applications in a variety of transducers, actuators and sensors. Most of the current commercial applications for ferroelectric materials are based on piezoceramics and magnetostrictive materials, despite the fact that they exhibit many deficiencies, such as low strain levels, brittleness, heavy weight, high processing temperatures and processing difficulties when producing parts having complicated shapes. In sharp contrast, ferroelectric polymers exhibit many desirable properties, such as flexibility, light weight, high mechanical strength, an ability to be processed readily into large area films, and an ability to be molded readily into a variety of configurations. However, despite these advantages over ceramic materials, most ferroelectric polymers suffer the disadvantage of having a low electric field sensitivity, in terms of dielectric constant, piezoelectric coefficient, electromechanical coupling coefficient and field induced strain, which limit their applications.
Invention description:
A new class of ferroelectric terpolymers having an exceptionally large electrostrictive response (>3%) induced by external electric field at ambient temperature comprise 50-80 mole % of vinylidene fluoride (VDF), 15-40 mole % of trifluoroethylene (TrFE) and 2-20 mole % of at least one bulky monomer, such as chlorotrifluoroethylene (CTFE) or hexafluoropropene (HFP). These semicrystalline terpolymers behave like a ferroelectric relaxor having a rapid electric field-induced mechanical response, due to a low Curie temperature (phase transition between polar and nonpolar crystalline domains at or near ambient temperature) and high dielectric constant. A combination of bulk polymerization and free radical polymerization using oxidation adducts of an organoborane as the free radical initiator may be used to prepare the terpolymers, such that the terpolymers are characterized by good processibility, high purity and uniform molecular structure.
Advantages:
- High dielectric constant
- Large electrostrictive response (>3%)
- Terpolymers have good processibility, high purity and uniform molecular structure
Contact:
Bradley A. Swope
Sr. Technology Licensing Officer
The Pennsylvania State University
113 Technology Center
University Park, PA 16802
Phone: (814) 863-5987
Fax: (814) 865-3591
E-mail: bradswope@psu.edu |
