Page 351 - IJB-9-1

International Journal of Bioprinting High-performance electrospun PVDF/AgNP/Mxene fiber

PVDF/MXene, and PVDF/AgNP/MXene fiber sheets,
respectively; as expected, the color varied from white to
blackish upon increasing the concentration of MXene.

We used SEM to investigate the morphologies of
MXene composite fibers in greater detail. A well-aligned
fiber at the contact would favor the production of well-
oriented β-form extended-chain crystallites at the
interface. The diameters of the fibers were determined
from SEM images recorded at four different locations
along their length. The electrospinning of MXene
composite fibers resulted in fibers that were perfectly
aligned with one another. Although the PVDF/AgNP/
MXene fibers were continuous and had porous network
topologies, there was no beading throughout the fibers. Figure 3. (A) FTIR spectra of pure PVDF, PVDF/MXene, and PVDF/
Figure 1H–J shows high-magnification SEM images of AgNP/MXene composite materials and (B) their corresponding tensile
PVDF/MXene/AgNP composite fibers. Thinner fibers stress-strain curves.
were formed in the presence of MXene, most likely because
of the increased static electrical field caused by the higher 38.14, 44.4, 64.4, and 77.6°, respectively (Figure 4A). The
solution conductivity. There were a few minor bumps, usual (110) diffraction peak of α-phase PVDF, appearing at
resulting in unsmooth fibers, as well as micron-sized a value of 2θ of 20.2°, became less prominent following the
MXene, which resulted in slightly uneven fiber diameters; increase in concentration of MXene in the films. Similarly,
the PVDF/MXene fiber diameters ranged from 0.39 to the (021) diffraction peak of β-phase PVDF appeared at
4.50 µm (Figure 1I). With the addition of AgNP, the fibers a value of 2θ of 20.8°. These changes in crystalline form
became clear and dry, presumably because the AgNPs suggested that the PVDF chains were nucleated by MXene
enhanced the thermal conduction, thereby enhancing in a very heterogeneous manner and indirectly confirmed
solvent evaporation during the fly process in the electrical that there were strong interactions at the interface between
field and following the deposition on the rotating disk. MXene/AgNP and PVDF.
The diameters of the PVDF/AgNP/MXene fibers ranged When mechanical forces are applied to piezoelectric
from 1.0 to 6.5 µm (Figure 1J). Nevertheless, the fiber materials, they deform and change their polarization
surfaces had uneven structures (surface roughness and density almost instantly. This behavior causes a voltage
bumps), presumably due to regionally nonuniform MXene to appear in the polar direction, and vice versa. The
distributions produced by slower solvent evaporation, as a composite products exhibited an outstanding mechanical
result of interactions between the hydrophilic MXene and performance, owing to strengthening mechanisms. The
the humid atmosphere (Figure 1H). practical applications of composite materials are limited
We used FTIR spectroscopy and XRD to determine by poor mechanical properties. Therefore, the mechanical
the chemical and crystalline structures of the materials properties of piezoelectric materials are crucial factors
used in this study. Figure 3A presents the FTIR spectra when attempting to increase the piezoelectric response.
of MXene, AgNPs, and PVDF in range from 1,700 to However, they are often overlooked when engineering
750 cm . Signals at 840, 1,071, 1,275, and 1,402 cm are piezoelectric materials. Although Young’s modulus has
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typical of the β-phase. After the addition of MXene, the been studied in relation to the piezoelectric characteristics
β-phase became more apparent, and the width became of piezoelectric polymers, there is still a need to investigate
narrower. The sample containing AgNPs had the highest the effects of other mechanical qualities, including
content of the β-phase. Signals for Ti–O, C–O, and C–F compression modulus and flexibility [83,95-97] . Polymer
bonds in the MXene were also evident. The signal for Ti–O composite materials are not useful if they have poor
bonds moved from 1,624 to 1,644 cm , revealing that the mechanical qualities [51–53] . Therefore, the mechanical
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C–F bonds of PVDF and the surface groups of MXene characteristics of PVDF as well as PVDF/MXene and
interacted through dipole–dipole interactions. PVDF/AgNP/MXene composites were investigated
(Figure 3B). As observed in our experiments, the AgNP-
The (002) diffraction peak of MXene was evident in and-MXene-based piezoelectric fiber displayed superior
the XRD patterns of PVDF/AgNP/MXene fiber films. In mechanical characteristics. The mechanical properties of
addition, the signals for the (111), (200), (221), and (311) the two types of fillers were different due to their varying
planes of the Ag crystal were all present at values of 2θ of volume fractions. The following observation demonstrated

Volume 9 Issue 1 (2023)olume 9 Issue 1 (2023)
V 343 https://doi.org/10.18063/ijb.v9i1.647