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<p>Herein, a simple method for preparing poly(vinylidene fluoride) (PVDF) films with controlled <i>β/γ</i> ratios by spin-coating assisted by potassium bromide (KBr) is proposed. The results show that the relative fraction of the <i>β</i> phase (denoted as <i>F</i><sub><i>β</i></sub>) for the films prepared on the KBr surface first decreased until a critical temperature (denoted as <i>T</i><sub>c</sub>) was reached, and then increased with increasing spin-coating temperature. This was related to the dissolved K and Br ions in the films. Further experiments showed that below <i>T</i><sub>c</sub>, high humidity can enhance <i>F</i><sub><i>β</i></sub> but exhibit an adverse effect at and above <i>T</i><sub>c</sub>. The high content of K and Br ions in the PVDF/KBr blend film and larger shear stress can facilitate the formation of the <i>β</i> phase, leading exclusively to the formation of <i>β</i>- and <i>γ</i>-phases. The mechanism responsible for the change in <i>F</i><sub><i>β</i></sub> with temperature was proposed: below <i>T</i><sub>c</sub>, the decrease in water intake with increasing temperature results in the decline of <i>F</i><sub><i>β</i></sub>, whereas above <i>T</i><sub>c</sub>, the increase in <i>F</i><sub><i>β</i></sub> with temperature is attributed to the synergistic effect of ions and shear stress. Ultimately, this paves the way for fabricating PVDF films with tailored <i>β/γ</i> ratios for electroactive and energy-harvesting applications.</p>

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Poly(vinylidene fluoride) of Different β-Phase/γ-Phase Ratio Prepared by Heat Controlled Spin Coating and Potassium Bromide as Nucleating Agent

  • 期刊论文

  • 发表日期：

    2025年3月13日

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  • Hai-Peng Li,
  • Jia-Meng Liang,
  • Hao-Ying Song,
  • Han-Qi Zhu,
  • Wen-Peng Zhao,
  • Shao-Juan Wang,
  • Hao Zhang,
  • Shou-Ke Yan

摘要

Herein, a simple method for preparing poly(vinylidene fluoride) (PVDF) films with controlled β/γ ratios by spin-coating assisted by potassium bromide (KBr) is proposed. The results show that the relative fraction of the β phase (denoted as Fβ) for the films prepared on the KBr surface first decreased until a critical temperature (denoted as Tc) was reached, and then increased with increasing spin-coating temperature. This was related to the dissolved K and Br ions in the films. Further experiments showed that below Tc, high humidity can enhance Fβ but exhibit an adverse effect at and above Tc. The high content of K and Br ions in the PVDF/KBr blend film and larger shear stress can facilitate the formation of the β phase, leading exclusively to the formation of β- and γ-phases. The mechanism responsible for the change in Fβ with temperature was proposed: below Tc, the decrease in water intake with increasing temperature results in the decline of Fβ, whereas above Tc, the increase in Fβ with temperature is attributed to the synergistic effect of ions and shear stress. Ultimately, this paves the way for fabricating PVDF films with tailored β/γ ratios for electroactive and energy-harvesting applications.