Fabrication and characterization of polydiacetylene supramolecules in electrospun polyvinylidene fluoride nanofibers with dual colorimetric and piezoelectric responses

Abstract

The ability to prepare Polydiacetylenes based materials in the polyvinylidene fluoride matrix polymer is interesting due to the combination of colorimetric and electrical signaling. The new PVDF/PDA composite nanofibers were prepared via the electrospinning method. The self-assembly of diacetylene monomers (PCDAs) occurred during the electrospinning process. The assembled diacetylene monomers in the PVDF nanofibres were further polymerized to form PDA. Full factorial experimental design was applied to investigate the influence of PVDF concentration and PCDA content on the morphology of nanofibers. The colorimetric transitional of the uniform and beadless PVDF/PDA nanofibers were studied as a function of temperature. The crystal polymorphism of these structures were evaluated using Fourier transform infrared, differential scanning calorimetry, and wide angle X-Ray diffraction. The piezoelectric response of the PVDF/PDA nanofibers in the red and blue phases was also measured. The results showed that a combination of colorimetric and piezoelectric responses is available with composite nanofibers of PVDF/PDA. The polymorphism investigation demonstrated that assembled PCDAs have the effect of inhibiting the growth of non-polar α phase crystals, while promoting the growth of polar β phase. Moreover, the electrospun PVDF/PCDA nanofibers after UV-irradiation and formation of PDA exhibited greater intensity of β-phase in comparison to that before irradiation. However, the red phase of PVDF/PDA nanofibers indicated less fraction of β-phase than the blue phase. The blue-to-red color transition of PVDF/PDA composite nanofibers accompanied by the variation of piezoelectric response could open new avenues for many sensor applications.