Influence of Microstructure on the Nanomechanical Properties of Polymorphic Phases of Poly(vinylidene fluoride)

Abstract

Poly(vinylidine fluoride) (PVDF) is a semicrystalline polymer which is known to exist in several polymorphic phases, namely, α, β, and γ. Each one of these polymorphic phases is characterized by unique features such as spherulite formation in the case of the α and γ phases and the presence of large piezoelectric and ferroelectric activity in the β phase. Despite being widely used as thin coatings in sensors, lack of reports on nanomechanical properties suggests that investigation of mechanical properties of PVDF, let alone those of its polymorphic phases, seems to have evaded the sight of the research community. Herein, we report the nanomechanical properties of the α, β, and γ phases of PVDF. The modulus and hardness values were evaluated from nanoindentation experiments; it was found that the electroactive β phase is the softest among the three polymorphic phases. This result was further confirmed by scratch experiments. We have attempted to establish a correlation between the microstructure and nanomechanical properties of these phases. This work sheds light on the mechanisms responsible for the observed mechanical behavior and the role of tie molecules and amorphous content in providing flexibility to the polymer.

Mechanical Nanoscale Polarization Control in Ferroelectric PVDF‐TrFE Films

“…Reports on ferroelastic phenomena of PVDFbased polymers are yet very scarce. [34,35] If the lattice is elongated/shortened along the polarization direction, straining a ferroelectric crystal can reorient the polarization. For example, the polarization is parallel to the long c-axis in tetragonal ferroelectrics like PbZr 0.2 Ti 0.8 O 3 .…”

Enhancing the electroactive phases in freestanding flexible films of MoS 2 / PVDF

“…Also for the highest loading of 1 wt% of the fillers the fibers were absent. The fibers are known to responsible for the crystalline nature of the polymer 37 . Their absence, as observed in the FESEM images, could attribute to the amorphous behavior as evident from the XRD patterns.…”

Boosting Energy Storage of Poly(vinylidene difluoride) Nanocomposite Based Flexible Self-Standing Film with Low Amount of Hydroxylated V2O5

“…As the crystallinity increases, the size of the spherulites decreases. More number of spherulites of lower sizes could be there as the rate of grain growth is lower than the rate of nucleation process . The low roughness of the nanocomposite can also be due to the partially hydrophilic nature of Hy-V 2 O 5 , which speeds up the exchange of solvent and nonsolvent during the phase change. , The measured root-mean-square roughness ( R rms ) for PVDF is 9.079 ± 0.5 nm, and for PVDF/Hy-V 2 O 5 (5%) it is 8.588 ± 0.5 nm, from the green line shown in the inset in the Figure (a,b).…”

“…The micrographs in Figure (d–f) reveal that as the Hy-V 2 O 5 nanoparticles are loaded to the PVDF matrix, the spherulite size is decreased and difficult to resolve, which is clearly observable in the Figure (c) for pure PVDF. Further, loading of 5% vol filler may have increased the nucleation process as compared to the grain growth process because the nanofiller can work as the nucleation sites, which leads to the invisible smaller spherulite in more numbers making it smoother . As seen in Figure (f), there may be partial agglomeration of the V 2 O 5 filler nanoparticles due to hydroxylation.…”