Faculty Sponsor's Department:
It is known that oligovinylidene difluorides (OVDF) are one the best materials to exhibit piezoelectric and ferroelectric properties as a result of displaying a net dipole once they are in the β form. The β form is defined by the existence of all fluorine substituents appearing in the trans conformation of the polymer chain compared the α form which has no net dipole due to the gauche conformation. It is possible to induce the β form by heating and cooling the material or through mechanical manipulation of the polymer such as stretching and compressing the material. By applying an electrical field to the polymer, the chains can become aligned forming a macro-dipole and ultimately presenting itself for potential use in piezoelectric and memory devices. It is of great importance to industry to be able to develop such materials that are not only highly stable but are able to retain these characteristics while in the solid-state.
We propose the use of supramolecular chemical interactions in order to develop a material that has a well-defined mesogenic structure and take advantage of a known molecules tendency to aggregate forming self-assembling π conjugated stacks. Pthalocyanine was chosen for its versatile physical properties –light-harvesting and semi-conductivity– which will be united with OVDF’s piezoelectric and ferroelectric properties. We have developed a facile method for the synthesis of discotic pthalocyanine “cores” that have been successfully coupled with eight OVDF chains in order to provide directionality for the polymers and form a macro-dipole once the “cores” form stacks.
We have characterized the monomer form of the material using an array of analytical methods such as absorption, mass-spectrometry, gel permeation chromatography (GPC), proton nuclear magnetic resonance (1H-NMR), and fluorine nuclear magnetic resonance (19F-NMR). We intend to study the aggregate form of the material by polarized optical microscopy and differential scanning calorimetry (DSC) while further analysis of the ferroelectric and piezoelectric properties will be performed using other methods.