Elsevier

European Polymer Journal

Volume 109, December 2018, Pages 336-340
European Polymer Journal

Short communication
Electrospun poly(vinylidene fluoride-trifluoroethylene) based flexible magnetoelectric nanofibers

https://doi.org/10.1016/j.eurpolymj.2018.09.045Get rights and content

Abstract

Flexible multiferroic nanofibers of poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) containing 20% w/w of bismuth ferrite doped with neodymium and cobalt (Nd0.05Bi0.95Fe0.95Co0.05O3) nanoparticles were fabricated by electrospinning. SEM micrographs show well aligned nanofibers with average diameter of 420 nm, X-Ray diffraction revealed R3c crystalline structure corresponding to Nd0.05Bi0.95Fe0.95Co0.05O3 and crystallinity β phase of PVDF-TrFE polymer. FTIR spectra and DSC thermogram were used to investigate the crystallization behavior of PVDF-TrFE and showed pure β phase crystals and high degree of crystallinity. Dielectric measurements determined a low conductivity was found (3 × 10−6–1 × 10−9 S) together with a piezoelectric coefficient of 35 pm/V (−d33) and low permittivity (εr = 30–42). Obtained nanofibers displayed a ferromagnetic hysteresis loop, with coercivity of 140 mT and remnant magnetization of 0.580 Am2/kg at room temperature. The coexistence of magnetic hysteresis and ferroelectric properties in Nd0.05Bi0.95Fe0.95Co0.05O3/PVDF-TrFE nanofibers indicates magnetoelectric performance and hint for potential applications on technological devices.

Introduction

Multiferroic materials have attracted much attention in recent years, due to their outstanding applications in technological devices. These materials couple at least two ferroic properties (antiferro-ferromagnetism, ferroelectricity and ferroelasticity) simultaneously [1].

The coupling of the ferroic properties of ferromagnetism and ferroelectricity produce the magnetoelectric effect. The magnetoelectrical effect occurs as a product of mechanical deformation from magnetostriction and results in dielectric polarization due to the piezoelectric effect, allowing coupling of ferroic properties at room temperature [2]. There are few single-phase materials that couple at least two ferroic properties with high magnetoelectric values. Due to this, manufacture of magnetoelectric composites using ferromagnets and piezoelectric materials has become popular.

The most common magnetic materials used to fabricate magnetoelectric composites are metals, alloys and ceramics [3], [4], [5]. On the other hand, piezoelectric materials commonly used are ceramics [6], [7], [8]; however, polymers have been gaining interest due to the appearance of ferroelectric polymers such as PVDF, which not only grant ferroelectric property, but also ferroelastic properties [9], [10], [11], [12]. However, polyvinylidene fluoride can present three crystalline phases, Fig. 1, α phase with alternate conformations trans - gauche (TGTG), β phase only with trans conformations (TTTT) and γ phase (TTTG), from these three phases, only β-phase is relevant for electrical applications due to his polarization (ferroelectric properties). The co-polymer PVDF-TrFE crystallizes preferentially in β phase with all trans structural conformation (TTTT) due to the trifluoroethylene structure that prevents the ordering in gauche [13], [14], [15]. In addition, the confinement of the polymer due to the nanofibers, forces the compacting of the structure and crystallizes in β-phase [16], [17], [18], [19].

By combining a polymeric matrix with magnetic nanoparticles, result in flexoelectric material that may be manufactured on a large scale, allowing for a wide array of applications, sensors [20], actuators [21], energy conversion and storage [22], magnetoelectric memory devices [23], batteries [24], [25], distillation [26], tissue engineering [27], etc.

An effective coupling of these properties is nonetheless not always present in composites. This is because the coupling depends on the magnetostriction capacity of the magnetic material and the capacity of the ferroelectric material to respond to the mechanical stimulation of the magnetostrictive material. Thus, a material based on BiFeO3, known to have both ferroelectricity and anti-ferromagnetism, is used in this work as aggregated in nanofibers due to its particle size smaller than 62 nm (Cycle size of spin cycloydal for BiFeO3 is 32 nm) [28], [29], this allows the material to change from antiferromagnetism to ferromagnetism [30], [31]. In this work, nanometric fibers of PVDF-TrFE were loaded with magnetic particles of Nd0.05Bi0.95Fe0.95Co0.05O3 in order to obtain flexible magnetoelectric materials.

Section snippets

Experiments

Ceramic material Nd0.05Bi0.95Fe0.95Co0.05O3, was prepared using a method previously published by our research group [30]. The co-polymer PVDF-TrFE 80/20 (80% of PVDF and 20% of TrFE) was purchased from PIEZOTECH ARKEMA group. It was dissolved in 10 mL of N,N-dimethylacetamide (DMAc) and stirred/heated for 3 h to allow all the polymer chains to extend. Once the polymer was dissolved, 20% weight of the ceramic material was added to the polymer and sonicated for 15 min to allow the dispersion of

Results and discussion

Intense and well-defined bands in the IR spectrum were due to the presence of the fluorine atoms of the polymer. The IR spectrum of the composite Nd0.05Bi0.95Fe0.95Co0.05O3/PVFF-TrFE obtained by electrospinning is shown in Fig. 2. The characteristic vibrational modes of the “β” phase of PVDF-TrFE are observed in 850 and 1295 cm−1 and can be assigned to asymmetric stretching of CF2, symmetric stretching of CF2 coupled to CCC scissoring, these vibrational modes are associated with three or more

Conclusions

In summary, composite Nd0.05Bi0.95Fe0.95Co0.05O3/PVFF-TrFE nanofibers with average diameter 480 ± 80 nm were obtained by the electrospinning. The fiber composites show high crystallinity with a crystallization temperature of 149° C. In addition, the electroactive β phase in a proportion of 98%, which lead to low conductivities and a high piezoelectric coefficient. These electrical and magnetic properties of composite nanomaterial, hint for possible applications in Magneto-Electric devices.

Acknowledgments

N. Hernandez and I.B. Dzul thank Consejo Nacional de Ciencia y Tecnología (CONACYT) for fellowship.

References (63)

  • Z. Cui et al.

    Prog. Polym. Sci.

    (2015)
  • A.C. Lopes et al.

    Eur. Polym. J.

    (2018)
  • R. Mejri et al.

    Eur. Polym. J.

    (2016)
  • S. Rajendran et al.

    Eur. Polym. J.

    (2002)
  • C. Ben Osman et al.

    Eur. Polym. J.

    (2016)
  • A. Manuel Stephan

    Eur. Polym. J.

    (2006)
  • M. Sivakumar et al.

    Eur. Polym. J.

    (2007)
  • F.A. AlMarzooqi et al.

    Eur. Polym. J.

    (2016)
  • N. Abzan et al.

    Eur. Polym. J.

    (2018)
  • N. Hernández et al.

    J. Magn. Magn. Mater.

    (2015)
  • N. Hernández et al.

    J. Alloy. Compd.

    (2015)
  • A.A. Prabu et al.

    Vib. Spectrosc.

    (2009)
  • K. Tashiro et al.

    Polymer

    (1988)
  • A. Baji et al.

    Compos. Sci. Technol.

    (2013)
  • A. Baji et al.

    Compos. Sci. Technol.

    (2011)
  • Y.K.A. Low et al.

    Mater. Sci. Eng., C

    (2014)
  • P. Martins et al.

    Prog. Polym. Sci.

    (2014)
  • L. Yang et al.

    Polymer

    (2013)
  • A. Rahimpour et al.

    Appl. Surf. Sci.

    (2009)
  • I.T.S. Garcia et al.

    Polymer

    (1998)
  • L. Yang et al.

    Compos. Sci. Technol.

    (2016)
  • W.A. Yee et al.

    Polymer

    (2008)
  • S. You et al.

    Mater. Lett.

    (2014)
  • A. Lonjon et al.

    J. Non-Cryst. Solids

    (2012)
  • M. Fiebig et al.

    Nat. Rev. Mater.

    (2016)
  • M. Fiebig

    J. Phys. D Appl. Phys.

    (2005)
  • H. Amorín et al.

    ACS Appl. Mater. Interfaces

    (2017)
  • T. Walther et al.

    J. Am. Ceram. Soc.

    (2017)
  • W. Wang et al.

    Sci. Rep.

    (2013)
  • N. Fumio et al.

    Adv. Eng. Mater.

    (2018)
  • C.-W. Nan et al.

    Appl. Phys. Lett.

    (2002)
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