Actuation Behavior of Polylactic Acid Fiber Films Prepared by Electrospinning

Abstract

A poly-DL-lactide (PLA) fiber film was prepared using the electrospinning method. This film consisted of randomly oriented PLA nanofibers. Consequently, it had sponge-like structure and was quite soft compared to PLA films prepared by spin coating. The average diameter of the fibers and the density of the film were 730 nm and 20%, respectively. By applying a voltage, the PLA film was subjected to electric-field-induced strain: expansion and compression in the thickness direction. When a voltage of -200 V was applied to the film, its thickness shrank from 13.5 µm to 10.0 µm (a 26% reduction). Electric-field-induced strain can occur via two different mechanisms: The first is electrostrictive behavior. That. is, in a highly electric field region, a change of film thickness occurs (compression only) from the electrostatic force between electrodes. The second mechanism is piezoelectric-like behavior that occurs in racemic PLA, wherein a PLA nanofiber is expanded and compressed by applying positive and negative voltage. Such piezoelectric-like behavior was not observed in spin-coated PLA films.

Polarized FT-IR Study of Uniaxially Aligned Electrospun Poly(DL-Lactic Acid) Fiber Films

“…In contrast, racemic mixture of PLLA and PDLA, i.e., poly-DL-lactic acid (PDLLA), have not shown piezoelectricity. However, in our recent study, a PDLLA fiber film prepared by electrospinning, a simple method for the preparation of polymer nanofibers and/or non-woven fabrics of nanofibers, has been shown to have piezoelectric-like behavior [10,11]. The film, consisting of a number of randomly deposited PDLLA fibers, showed large strain-to-thickness direction, which was attributed to an inverse piezoelectric-like effect.…”

Significance of Nanomaterials in Wearables: A Review on Wearable Actuators and Sensors

“…Among different fabrication processes, electrospinning, [6,40] spray coating, [41] knitting, [42,43] weaving, [43] and solution casting [44] are key interests of researchers currently. Among different fabrication processes, electrospinning, [6,40] spray coating, [41] knitting, [42,43] weaving, [43] and solution casting [44] are key interests of researchers currently.…”

Amorphous Electrically Actuating Submicron Fiber Waveguides

“…In addition, ES can potentially assist both low cost/energy manufacturing and large‐area fabrication by providing both high material utilization ratios and a high positional accuracies . Hence, features of the ES technique make it possible to produce functional polymer submicron fiber devices, including generators, actuators, transistors, and waveguides . Several studies reported high piezoelectric performances for electrospun submicron fibers composed of piezoelectric polymers, such as poly(vinylidene fluoride) (PVDF) and poly(vinylidenefluoride‐ co ‐trifluoroethylene) (PVDF‐TrFE), without using a postpoling treatment .…”

“…The induced piezoelectricity was reported to result from both the unique uniaxial alignment of the polymer main chains and the orientation polarization in the fibers caused by the ES procedure . Recently, we demonstrated that, similar to the inverse‐piezoelectric effect of piezoelectric materials, electrospun submicron fiber mats composed of the amorphous polymer poly(DL‐lactic acid) (P DL LA) exhibit high degrees of electrical actuation for mat thicknesses up to 26% depending on both the polarity and the magnitude of the applied voltages . Stretched films of poly(lactic acid) only exhibit shear piezoelectricity and electrical actuation when they are either composed of pure optical isomers, such as poly(L‐lactic acid) (PLLA) or poly(D‐lactic acid) (PDLA), or when they exhibit stereocomplex structures .…”