Preparation method for polyvinylidene fluoride nanometer film with beta crystal phase

Abstract

The invention provides a preparation method for a polyvinylidene fluoride (PVDF) nanometer film with a beta crystal phase, which belongs to the fields of pyroelectric thin film materials and terahertz detection. The preparation method comprises the following steps: dissolving graphene oxide and polyvinylidene fluoride in an organic solvent and carrying out ultrasonic treatment and magnetic stirring so as to obtain a uniformly dispersed film-making solution; standing the film-making solution for defoaming; preparing a wet film by using a spin coating method; and subjecting the film to heat treatment in an atmospheric environment to realize drying and crystallization of the film so as to obtain the polyvinylidene fluoride nanometer film with the beta crystal phase. According to the invention, the content of the beta crystal phase in PVDF is increased by doping of GO and the PVDF nanometer film is prepared by using the spin coating method; the preparation method is simple, is easy to control, has low requirements on equipment and low cost and can realize preparation under common atmospheric conditions; and the prepared PVDF film is uniform and smooth, has good compactness and stable pyroelectric performance and provides powerful support for development of a thin-film pyroelectric terahertz detector.

Description

technical field [0001] The invention belongs to the field of pyroelectric film materials and the field of terahertz detection, and relates to a preparation method of a functional nano film, in particular to a preparation method of a polyvinylidene fluoride (PVDF) nano film with a β crystal phase. Background technique [0002] Polyvinylidene fluoride (PVDF) has good piezoelectricity, pyroelectricity and ferroelectricity. As a thin film functional material, it has been widely used in the fields of sensors, transducers, and biomedicine. [0003] PVDF has a variety of crystal structures, and the five known structures are α, β, γ, δ and ε. The α crystal phase is TGTG -1 Structure, dipole positive and negative charge center overlap spontaneous polarization is zero, no piezoelectric properties. The β crystal phase is all-trans type with high spontaneous polarization, and is an important crystal phase structure in PVDF. However, the α-crystal phase is the structure with the lowe...

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Problems solved by technology

[0004] At present, a PVDF film with a β crystal phase can be obtained by mechanical stretching. Literature: A.SalimietcFTIRstudiesofβ-phasecrystalformationinstretchedPVDFfilms, 2003, 22:699-704A.Salimi discloses that a PVDF film was prepared by mechanical stretching, and the prepared PVDF film The β crystal phase content is not high, the prepared film is thicker, and the film cannot be accurately prepared on the desired substrate

The electrospinning process is also one of the common methods for preparing PVDF films. Literature: YongjinAhnetcEnhancedPiezoelectricPropertiesofElectrospunPoly(vinylidenefluoride) / MultiwalledCarbonNanotubeCompositesDuetoHighβ-PhaseFormationinPoly(vinylidenefluoride), 2013,117:11791-11799, but its method discloses the use of PVD electrospinning F film equipment High requirements, cumbersome preparation process, not suitable for large-scale production

In recent years, doped nanoparticles (such as titanium dioxide, graphene, carbon nanotubes, etc.) have attracted widespread attention; literature: WCGanetcEffectofTiO 2 onenhancedpyroelectricactivityofPVDFcomposite, 2014, 23WCGan discloses the preparation of PVDF film by doping titanium dioxide, but the content of β crystal phase in the prepared PVDF film is not large, mainly because of the formation of δ crystal phase, and the polarization intensity of δ crystal phase is only β crystal phase and the literature: YuJetcGraphenenanocompositesbasedonpoly(vinylidenefluoride)structureandproperties, 2011,32:1483–1491 discloses the use of adding a small amount of graphene in PVDF to prepare PVDF films, but in this preparation method, due to the dispersion of graphene in the solvent Very poor, it must be well dispersed in PVDF by adding dispersant or surface modification; Graphene and casting method to prepare PVDF film, this method can overcome the difficulty that other nanomaterials cannot be well dispersed in PVDF, but the thickness of the film prepared by casting method is generally on the order of microns

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