The properties and applications of fluorine-containing polymer films with piezo- and pyro-activity

Polymer films based on poly(vinylidene fluoride) and its copolymers, which exhibit piezo- and pyro-electic properties after appropriate treatment, are described. The principal advantages of materials of this class include high values of the piezomoduli, which permit their practical use. Another valuable property, which is difficult to achieve in inorganic materials, is the wide range of frequencies over which the given active element can operate. The possibility of achieving large areas and fairly simple methods of preparation of thin films also leads to the assignment of the above polymers to the category of promising materials for the creation of new classes of recording devices. The trends in the development of new instruments based on these materials, where use is made of the phenomenon of photopyroelectric activity are demonstrated. The advantages of using these materials for medical techniques are noted. The flexibility of the film and its acoustic impedance, which is close to that of a biological tissue, as well as the properties noted above place it beyond competition with other materials. Furthermore, the ferroelectric nature of the above polymers makes them promising for use in nonlinear optics. The bibliography includes 89 references.