Ferroelectric block copolymers: from self-assembly towards potential application

Ferroelectric polymers, such as poly(vinylidene fluoride) (PVDF), can crystallize in polar β-phase where C-F bonds are arranged with all the dipoles oriented perpendicular to the main chain and can be switched up or down by applying an electric field. The high density of crystals prevents the dipole disorientation after the field removal, making them a good candidate for information storage. The presence of dipoles in PVDF and its high dielectric constant offer enormous potential in electrical energy storage. However, for this application, the ferroelectric nature of the polymer represents a disadvantage and can significantly reduce the efficiency of the device. The additional drawback of ferroelectric polymers is the lack of functionality that can add extra properties to the material and expand its use. Therefore, it would be highly beneficial to develop a simple method that can simultaneously tailor the ferroelectricity in PVDF-based polymers and add functionality to their structure.

The self-assembly of PVDF-based block copolymers represents a convenient way to prepare functional ferroelectric materials with easily tunable properties. Block copolymers consist of two different polymer blocks covalently linked to each other and which can phase separate into highly ordered nanostructures. In addition, the incorporation of the insulating block in the structure of the ferroelectric PVDF can screen the coupling forces between ferroelectric dipoles and induce a change in their response to the electric field.

This study investigates the self-assembly of PVDF-based block copolymers and explains their ferroelectric characteristics. The block copolymers were also used for the preparation of highly defined multiferroic nanocomposites, as well as nanocomposites with improved dielectric properties.

See also: Ferroelectric polymers made more versatile

Dissertation: http://hdl.handle.net/11370/d2b46925-3ccd-4e73-b923-2b12fb08fa18