Dhannoon, Diyar Jamal (2017-07). Investigation on Piezoelectric and Dielectric Properties of PVDF and Poly-Amino-Di-Fluoro-Borane (PADFB). Doctoral Dissertation.
Thesis
PVDF (polyvinylidene difluoride) is a well-known piezoelectric polymer that has nine polymorphs. This work reviews these polymorphs with respect to their thermal, mechanical and dynamical stability. Here, it is demonstrated through DFT calculations run by the VASP program that the (?) form (also known as 1p) has the highest dielectric constant, yet thermodynamically it is not the most favored form. My research on poly-amino-di-fluoro-borane (PADFB) is based on results obtained from PVDF analysis. PADFB has a structure very similar to that of PVDF. PADFB is not fully understood but is expected to have higher dielectric and piezoelectric constants. This work showed that PADFB also has nine stable polymorphs. One of these, 2pd(y), showed to have the lowest internal energy and highest piezoelectric property of PADFB polymorphs. PADFB has a very wide bandgap, which makes it a transparant, nonconductive piezoelectric material with huge potential in the smart screen industry.
