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Polyvinylidene fluoride (PVDF) has several crystal forms of which the α‐form is nonpolar, while the β‐form is polar and has the highest piezoelectric constant. α PVDF, when stretched, transforms into the β form, which has wide applications in sensors and actuators. Steered molecular dynamics simulations are used to study the transformation of a single chain of PVDF from a trans–gauche conformation to an all trans one. The Helmholtz free energy change (∆F) is estimated using Jarzynski's equality. The transformation starts at the chain ends followed by the transformation of the remaining chain. The free energy change for the transformation is found to be always positive, indicating that the TGTG' form has higher thermodynamic stability than the all trans form throughout the studied temperature range. With increasing temperature, free energy change for the transformation increases monotonically.

Polyvinylidene fluoride (PVDF), a polymer with three common crystal polymorphs (α, β, γ), has several practically useful properties, including piezoelectric properties. Accurate measurement of its crystalline polymorphs is important since only the β phase has the desired piezo properties. PVDF was processed into isotropic samples having predominantly α, β, and γ crystalline phases. These samples were analyzed with Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and differential scanning calorimetry (DSC). FTIR spectra were fitted with the Gaussian peaks for quantitative analysis of the phases. Peaks exclusive to the amorphous phase were identified and used for the amorphous phase quantification, leading to the accurate determination of the crystalline fraction. IR absorption coefficients for their respective peaks were calculated to quantify individual crystalline polymorphs in the sample. Pure phase spectra were extracted, and a linear combination of the pure phase spectra was fitted to the spectrum of a sample with different phases to accurately obtain the values of the phase fraction and the thickness of the sample.