Simply Preparation Of Self-poled PVDF Nanocomposites Through;in Situ And Electrospinning Formation Approaches:Synthesis And Formation Mechanisms

Poly（vinylidene fluoride）PVDF containing electroactive β phase has been widely used in applications of progressive technical and scientific fields,such as sensors and actuators.Enhanced β phase contributes to higher piezoelectric output.Hence,numerous efforts have been paid to promote the β phase by incorporating preformed（ex-situ）nanomaterial into the PVDF matrix.However,the method of ex-situ incorporation results in a non-uniform distribution of nanomaterial within the hosting polymer.To achieve a better homogeneity,we herein introduce a simple in-situ preparation approach.Herein,we prepared a flexible PVDF/CeO₂ nanocomposite using a facile in situ one-step formation of CeO₂ NPs within PVDF matrix.We studied the impact of the heterogeneous CeO₂ NPs as a nucleating agent of active β crystalline phase.UV-Visible spectra showed a broad band around 315 nm indicates the formation CeO₂ NPs.FTIR,XRD and SEM revealed that there is intimate interfacial interaction between CeO₂ NPs and PVDF chains.This interaction in turn promotes the electroactive phase content（-96%）.Furthermore,DSC and TGA techniques revealed the thermal stability enhancement of the nanocomposite by around 20 ℃referred to the strong interaction of the PVDF chains with CeO₂ NPs.Additionally,in this dissertation,we prepared the flexible biodegradable nanofiber for the first time using electrospinning to enhance β phase.Appropriate amount of DNA was incorporated into the PVDF/mixed solvent（DMF:acetone）spinning solution as nucleating agent.FTIR and XRD results revealed an electrostatic interaction at the interface between denatured DNA and-CH₂/CF₂-molecular dipoles of PVDF.This interaction was further clarified by XPS which introduced a peak shift of carbon bonded to fluorine and hydrogen due to the presence of DNA within PVDF.SEM images showed a decrease in nanofiber average diameter of PVDF/DNA nanofibers compared with that of PVDF.Consequently,contact angle measurement showed a significant increase in hydrophobicity by introducing DNA into the PVDF matrix.