High-Performance Coils and Yarns of Polymeric Piezoelectric Nanofibers

Abstract

We report on highly stretchable piezoelectric structures of electrospun PVDF-TrFE nanofibers. We fabricated nanofibrous PVDF-TrFE yarns via twisting their electrospun ribbons. Our results show that the twisting process not only increases the failure strain but also increases overall strength and toughness. The nanofibrous yarns achieved a remarkable energy to failure of up to 98 J/g. Through overtwisting process, we fabricated polymeric coils out of twisted yarns that stretched up to ∼740% strain. This enhancement in mechanical properties is likely induced by increased interactions between nanofibers, contributed by friction and van der Waals interactions, as well as favorable surface charge (Columbic) interactions as a result of piezoelectric effect, for which we present a theoretical model. The fabricated yarns and coils show great promise for applications in high-performance lightweight structural materials and superstretchable piezoelectric devices and flexible energy harvesting applications.

New twist on artificial muscles

“…In the future, electrospun polymer nanofiber yarns may enable a wide range of muscle hosts owing to their lower cost, high internal surface area, and large availability of functional polymers. For instance, electrospun fibers of piezoelectric poly(vinylidene fluoride trifluoroethylene) (PVDF-TrFE) have been demonstrated that can be twisted and coiled (50).…”

Biocompatibility and in vivo operation of implantable mesoporous PVDF-based nanogenerators

“…1B and C, respectively. When the shaker was operating at 20 Hz with a force of 6 N and a strain of ~0.1%, the average values of V oc and I sc reached 3.8 V and 3.5 µA, respectively, which outperformed a number of reported PVDF-based NGs [6,30,32,33,36]. This superior performance was mostly attributed to the optimized device geometry and structural advantage of the mesoporous PVDF thin film.…”

Polymer nanogenerators: Opportunities and challenges for large‐scale applications

“…Density functional theory has been used to calculate the piezoelectric coefficients and the full piezoelectric tensor for different copolymer configurations, also highlighting the role of shear forces contributions in flexible polymeric nanobeams . By using properly designed collectors, fibers can be arranged in various forms such as random mats, aligned strands, highly aligned arrays, ribbonds and yarns realized by twisting ribbons. Interesting, Baniasadi et al .…”

“…have found that the twisting process of aligned ribbons of PVDF‐TrFE increases up to a factor of 2 the strain to failure, strength, and toughness of the materials. In addition, coils fabricated by twisting the yarns [Figure (a)] exhibit an additional enhancement of the strain to failure (by a factor 4 with respect to yarn) with a maximum strain up to ∼740% . Ribbons generate an output voltage of tens of mV under bending while the combination of the piezoelectric charges and friction under stretching are considered to contribute to the enhancement of the mechanical properties though the increase of shear and compressive forces between nanofibers.…”