Exploring a novel treatment method to enhance polar phases in electrospun PVDF nanofibers
Date of Issue2009
School of Materials Science and Engineering
Poly (vinylidene fluoride) (PVDF) has drawn much attention due to the attractive properties such as piezo-, pyro-, and ferroelectricity, which are rarely exhibited in other polymers. The β phase has the largest spontaneous polarization (p) per unit cell of all polar phases and thus exhibits the highest piezo-, pyro and ferroelectric activities. This project aims to enhance β phase of PVDF through electrospinning and novel treatments. Supercritical carbon dioxide¬ (scCO2) was utilized in the treatment of electrospun films and the effects of the experiment parameters such as temperature and pressure of scCO2 were examined through characterization. It showed that the β phase enhancement increased with increasing pressure. Additionally, the enhancement in β phase was also observed to increase with increasing treatment temperature when the temperature was below 80 ºC. This polymorphic behavior was possibly due to the nucleation of β form crystal with existing β phase as nucleus promoted by supercritical CO2. Subsequently, multi-walled carbon nanotubes (MWCNTs) were added into PVDF solution with various weight percentages (PVDF/MWCNTs). It was found that the MWCNTs could promote β phase enhancement for PVDF via both electrospinning and spin-coating. Furthermore, supercritical CO2 treatment was utilized to the electrospun and spin-coated PVDF/ MWCNTs and found to further promote β phase enhancement.
Final Year Project (FYP)
Nanyang Technological University