Crystalline Structure Characterization of Polymer Samples

To identify the crystalline structure, Fourier transform infrared (FTIR) spectroscopy in attenuated total reflection (ATR) mode Bruker Alpha II spectrometer with platinum ATR attachment and a diamond crystal was used. Spectra in the 400–1500 cm⁻¹ range with a resolution of 1 cm⁻¹ was collected to characterize the crystalline structure of the samples. The degree of β crystallinity phase in the samples was calculated as follows (Cai et al., 2017 (link); Xin et al., 2018 (link); Kaspar et al., 2020 (link)) the degree was calculated using Eq. 1: $\mathrm{F}\left(\mathrm{\beta }\right)=\frac{{\mathrm{A}}_{\mathrm{\beta }}}{1.26{\mathrm{A}}_{\mathrm{\alpha }}+{\mathrm{A}}_{\mathrm{\beta }}}$ where Aα and Aβ are the absorbance values at 763 cm⁻¹ (CH₂ in-plane bending or rocking and CF₂ bending and skeletal bending) and 840 cm⁻¹ (CH₂ rocking and CF₂ asymmetrical stretching), respectively.
To confirm the crystalline structure, X-ray diffractometer (XRD) X'Pert Pro PANalytical equipped with Cu/Kα radiation (wavelength 0.15418 nm) in the 2θ range of 0°–50° at a scanning speed of 0.1°/min, was used and crystalline content was analysed according to Eq. 2: $\frac{\mathrm{I}\mathrm{\beta }}{\left(\mathrm{I}\mathrm{\alpha }+\mathrm{I}\mathrm{\gamma }+\mathrm{I}\mathrm{\beta }\right)}=\frac{\mathrm{I}\left(\frac{200}{110}\right)+\mathrm{I}\left(101\right)+\mathrm{I}\left(221\right)}{\left(\mathrm{I}\left(110\right)+\mathrm{I}\left(002\right)+\mathrm{I}\left(200/110\right)+\mathrm{I}\left(101\right)+\mathrm{I}\left(221\right)\right)}$ where the Iα, Iγ, and Iβ correspond to the intensity peaks of the α, γ, and β phases, respectively. The XRD peaks for the monoclinic α phase are 18.7° (020), 19.8° (110), and 26.5° (021), while the 20.7° (110/200), 36.6° (101) and 56° (221) peaks correspond to the orthorhombic β phase peak, and the γ phase peak can be attributed to 40° (002) (Cai et al., 2017 (link); Xin et al., 2018 (link); Kaspar et al., 2020 (link)):
The average crystallite size (D) was identified using the Scherrer using Eq. 3: $D=\frac{K\lambda }{B\cos \theta }$ where λ is the wavelength of 1.54 Å, B is the Full Width at Half Maximum (FWHM), θ is Bragg’s and K is a constant 0.94 [54]. The obtained data was analysed using the GraphPad Prism 10 software.