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P.K. Szewczyk


Recent publications
1.  Szewczyk P.K., Gradys A., Kyun Kim S., Persano L., Marzec M., Kryshtal A., Busolo T., Toncelli A., Pisignano D., Bernasik A., Kar-Narayan S., Sajkiewicz P., Stachewicz U., Enhanced piezoelectricity of electrospun polyvinylidene fluoride fibers for energy harvesting, ACS Applied Materials and Interfaces, ISSN: 1944-8244, DOI: 10.1021/acsami.0c02578, Vol.12, No.11, pp.13575-13583, 2020

Abstract:
Piezoelectric polymers are promising energy materials for wearable and implantable applications for replacing bulky batteries in small and flexible electronics. Therefore, many research studies are focused on understanding the behavior of polymers at a molecular level and designing new polymer-based generators using polyvinylidene fluoride (PVDF). In this work, we investigated the influence of voltage polarity and ambient relative humidity in electrospinning of PVDF for energy-harvesting applications. A multitechnique approach combining microscopy and spectroscopy was used to study the content of the β-phase and piezoelectric properties of PVDF fibers. We shed new light on β-phase crystallization in electrospun PVDF and showed the enhanced piezoelectric response of the PVDF fiber-based generator produced with the negative voltage polarity at a relative humidity of 60%. Above all, we proved that not only crystallinity but also surface chemistry is crucial for improving piezoelectric performance in PVDF fibers. Controlling relative humidity and voltage polarity increased the d33 piezoelectric coefficient for PVDF fibers by more than three times and allowed us to generate a power density of 0.6 μW·cm^–2 from PVDF membranes. This study showed that the electrospinning technique can be used as a single-step process for obtaining a vast spectrum of PVDF fibers exhibiting different physicochemical properties with β-phase crystallinity reaching up to 74%. The humidity and voltage polarity are critical factors in respect of chemistry of the material on piezoelectricity of PVDF fibers, which establishes a novel route to engineer materials for energy-harvesting and sensing applications.

Keywords:
PVDF, polymer crystallinity, electrospinning, piezoelectricity, voltage polarity

Affiliations:
Szewczyk P.K. - other affiliation
Gradys A. - IPPT PAN
Kyun Kim S. - other affiliation
Persano L. - other affiliation
Marzec M. - other affiliation
Kryshtal A. - other affiliation
Busolo T. - other affiliation
Toncelli A. - other affiliation
Pisignano D. - other affiliation
Bernasik A. - other affiliation
Kar-Narayan S. - other affiliation
Sajkiewicz P. - IPPT PAN
Stachewicz U. - AGH University of Science and Technology (PL)
2.  Ura D.P., Rosell-Llompart J., Zaszczyńska A., Vasilyev G., Gradys A., Szewczyk P.K., Knapczyk-Korczak J., Avrahami R., Šišková A.O., Arinstein A., Sajkiewicz P., Zussman E., Stachewicz U., The role of electrical polarity in electrospinning and on the mechanical and structural properties of as-spun fibers, Materials, ISSN: 1996-1944, DOI: 10.3390/ma13184169, Vol.13, No.18, pp.4169-1-18, 2020

Abstract:
Electric field strength and polarity in electrospinning processes and their effect on process dynamics and the physical properties of as-spun fibers is studied. Using a solution of the neutral polymer such as poly(methyl methacrylate) (PMMA) we explored the electrospun jet motion issued from a Taylor cone. We focused on the straight jet section up to the incipient stage of the bending instability and on the radius of the disk of the fibers deposited on the collecting electrode. A new correlation formula using dimensionless parameters was found, characterizing the effect of the electric field on the length of the straight jet, L˜E~E˜0.55. This correlation was found to be valid when the spinneret was either negatively or positively charged and the electrode grounded. The fiber deposition radius was found to be independent of the electric field strength and polarity. When the spinneret was negatively charged, L˜E was longer, the as-spun fibers were wider. The positively charged setup resulted in fibers with enhanced mechanical properties and higher crystallinity. This work demonstrates that often-overlooked electrical polarity and field strength parameters influence the dynamics of fiber electrospinning, which is crucial for designing polymer fiber properties and optimizing their collection.

Keywords:
fibers, electrical polarity, charges, electrospinning, PMMA, mechanical properties

Affiliations:
Ura D.P. - AGH University of Science and Technology (PL)
Rosell-Llompart J. - other affiliation
Zaszczyńska A. - IPPT PAN
Vasilyev G. - Technion-Israel Institute of Technology (IL)
Gradys A. - IPPT PAN
Szewczyk P.K. - other affiliation
Knapczyk-Korczak J. - other affiliation
Avrahami R. - other affiliation
Šišková A.O. - other affiliation
Arinstein A. - Technion-Israel Institute of Technology (IL)
Sajkiewicz P. - IPPT PAN
Zussman E. - Technion-Israel Institute of Technology (IL)
Stachewicz U. - AGH University of Science and Technology (PL)

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