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. 2019 Sep 5;12(18):2859.
doi: 10.3390/ma12182859.

Polarized Catalytic Polymer Nanofibers

Dinesh Lolla  1 , Ahmed Abutaleb  2 , Marjan A Kashfipour  3 , George G Chase  4
Affiliations

Polarized Catalytic Polymer Nanofibers

Dinesh Lolla et al. Materials (Basel). .

Abstract

Molecular scale modifications were achieved by spontaneous polarization which is favored in enhancements of β-crystallization phase inside polyvinylidene fluoride (PVDF) nanofibers (NFs). These improvements were much more effective in nano and submicron fibers compared to fibers with relatively larger diameters. Metallic nanoparticles (NPs) supported by nanofibrous membranes opened new vistas in filtration, catalysis, and serving as most reliable resources in numerous other industrial applications. In this research, hydrogenation of phenol was studied as a model to test the effectiveness of polarized PVDF nanofiber support embedded with agglomerated palladium (Pd) metallic nanoparticle diameters ranging from 5-50 nm supported on polymeric PVDF NFs with ~200 nm in cross-sectional diameters. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Energy Dispersive X-Ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR) and other analytical analysis revealed both molecular and surface morphological changes associated with polarization treatment. The results showed that the fibers mats heated to their curie temperature (150 °C) increased the catalytic activity and decreased the selectivity by yielding substantial amounts of undesired product (cyclohexanol) alongside with the desired product (cyclohexanone). Over 95% phenol conversion with excellent cyclohexanone selectivity was obtained less than nine hours of reaction using the polarized PVDF nanofibers as catalytic support structures.

Keywords: PVDF; cyclohexanone; electrospinning; heterogenous catalysis; phenol; polarization.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic of syringe pump electrospinning station with rotating cylindrical collector.
Figure 2
Figure 2
Perspective views of custom-made polarization device designed using Autodesk®-AutoCAD®-2015. Orientation of the electrospun fiber mat is indicated by the dotted white lines and aluminum electrodes are indicated by solid yellow lines. Copyright reprints from [18].
Figure 3
Figure 3
Schematic of batch reactor, not drawn to scale.
Figure 4
Figure 4
Preparation of electrospun polarized palladium (Pd)/PVDF.
Figure 5
Figure 5
SEM electron micrographs, associated fiber size distributions and EDX elemental compositions of PVDF electrospun fibers. Figure 5A, B are low and high magnification images of PVDF nanofibers, Figure 5C is fiber size distribution and 5D is elemental composition of the electrospun PVDF nanofibers.
Figure 6
Figure 6
A comparison of FTIR spectra profiles in the fingerprint region between 400–1800 cm−1.
Figure 7
Figure 7
SEM micrographs of catalytic particles embedded on to (A) as-spun, (B) heat-treated, and (C) polarized PVDF fibers and corresponding EDX spectra analysis of elemental composition on the bottom.
Figure 8
Figure 8
TEM micrographs of catalytic particles embedded on to (A) as-spun, (B) heat-treated, and (C) polarized PVDF fibers.
Figure 9
Figure 9
SEM (A), AFM (B,C,D), and DSA (E) characterizations of electrospun PVDF fibers.
Figure 10
Figure 10
Conversion of phenol (A,C,E) and selectivity of cyclohexanone (B,D,F) using as-spun, heat-treated, and polarized Pd/PVDF electrospun fibers.
See this image and copyright information in PMC

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