Faculty Publications
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Item Electrospun PVDF-based composite nanofabrics: An emerging trend toward energy harvesting(Elsevier, 2021) Shetty, S.; Anandhan, S.Poly(vinylidene fluoride) (PVDF) has gained attention in energy-related applications, due to its ferroelectric, piezoelectric, and pyroelectric properties. PVDF is a semicrystalline fluoropolymer having different phase domains based on its chain conformations. The polar domains contribute to its ferroelectric and piezoelectric characteristics. Electrospinning is a facile nanofabrication technique used to produce ultrafine fibers that self-integrates into functional webs/nanofabrics. This chapter emphasizes the electrospinning/filler route to tune the electroactive properties of PVDF-based composite nanofabrics and their applicabilities toward energy-related systems. The influence of various fillers/additives on the structure, morphology, and electroactive response of PVDF composite nanofabrics, including their incorporation into energy-related systems, is described in detail. Understanding the interplay between the filler and PVDF matrix coupled with electrospinning could contribute toward the fabrication of scalable and practical energy systems. © 2021 Elsevier Inc.Item Physico-chemical and piezoelectric characterization of electroactive nanofabrics based on functionalized graphene/talc nanolayers/PVDF for energy harvesting(Springer Science and Business Media B.V., 2021) Shetty, S.; Shanmugharaj, A.M.; Anandhan, S.Poly(vinylidene fluoride) (PVDF) is a versatile polymer, whose dielectric, piezoelectric and ferroelectric properties can be augmented by a range of processing routes and/or additives. We developed a flexible nanogenerator using electrospun PVDF/COOH-functionalized graphene nanosheet (FGNS)/talc nanosheet (TNS) hybrid nanocomposites. TNS loading was fixed at 0.50 wt% while FGNS loading was varied (0.05, 0.10, 0.15, and 0.20 wt %) in these nanofabrics and their structure–property relationship was explored. Incorporation of FGNS led to formation of an electrically conductive network in the polymer matrix aided by TNS and electrospinning. The uniform dispersion of the filler nanosheets led to effective enhancement of the electroactive ?-phase of the PVDF matrix. Crystallinity and polymorphism in these systems were explored by FTIR spectroscopy, X-ray diffraction and differential scanning calorimetry. A nanogenerator made of the nanofabric containing 0.5 wt% of TNS and 0.10 wt% of FGNS was mechanically impacted by pneumatic actuator (operating pressure 0.4 MPa), resulting in an output voltage of 12.9 V and a power density of 1.72 µW/cm2, respectively. The piezoelectric coefficient (d33) of this nanofiber system was 61 pm/V as revealed by piezoelectric force microscopy. These novel nanocomposites could be used in flexible energy-harvesting devices. © 2021, The Polymer Society, Taipei.Item Evaluation of piezoelectric behavior and biocompatibility of poly(vinylidene fluoride) ultrafine fibers with incorporated talc nanosheets(John Wiley and Sons Inc, 2022) Shetty, S.; SelvaKumar, S.; Salehi, S.; Pellert, A.; Scheibel, M.; Scheibel, T.; Anandhan, S.Herein, we fabricated biocompatible ultrafine fibers based on talc nanosheets (TNS)/PVDF composites that can exhibit robust electromechanical responses. Piezoresponse force microscopy (PFM) was extensively used to decode various characteristics, including ferroelectric and piezoelectric coefficients. The 0.5 wt% TNS dispersed ultrafine fibers exhibited well-defined ferroelectric characteristics with an enhanced piezoelectric coefficient (d33) of ≈43.3 pm/V compared to 10 pm/V measured for the pristine PVDF ultrafine fibers. It was observed that the piezoelectric coefficient values strongly depended on the morphology and electroactive phase fraction of the ensuing composite ultrafine fiber. The advantage of a high aspect ratio and surface charges offered by TNS alongside electrospinning augmented the composite ultrafine fiber's piezoelectric response. Further, in-vitro cytotoxicity of the TNS/PVDF composite ultrafine fibers was examined using BALB/3T3 fibroblasts based on ISO Standard 10993-5. Importantly, the new composite fibers showed no cytotoxic response and the exposed fibroblasts showed excellent viability. Thus, these fabricated TNS/PVDF piezoelectric ultrafine fibers are well suited for applications in bioelectronics, especially as flexible wearable electronic devices, including sensors. © 2022 Wiley Periodicals LLC.Item A systematic analysis on the electrospinnability of biocompatible poly(butylene adipate-co-terephthalate)(Institute of Physics, 2025) Das, A.; Anandhan, S.; Chethan, K.N.; Salins, S.S.; Shetty, R.; Shetty, S.Fine-tuning electrospun nanofibers is crucial for producing high-quality fibers. Taguchi Design of Experiment (DOE), along with various other computational techniques, has been used to optimize the electrospinning parameters of different polymers. Taguchi DOE has proven effective in optimizing electrospun nanofibers because it reduces the number of trials needed. In this study, the electrospinning parameters of poly (butylene adipate-co-terephthalate) (PBAT) were optimized and quantified using the Taguchi-based Response Surface Methodology (RSM) approach. The average fiber diameters were measured from Field Emission Scanning Electron Microscopy (FESEM) images using ImageJ software. Within the tested range of parameters and levels, the Analysis of Variance (ANOVA) study identified polymer concentration and flow rate as the most significant factors that influenced the fiber diameter. Polymer concentration accounting 56.94% of the variation, while Flow Rate (FR) accounts for 20.82%. The optimal parameter levels were predicted to be 10 wt% polymer concentration, 1 ml h?1 flow rate, 18 kV voltage, and a distance from tip to target of 15 cm, which yielded fibers with an average diameter of 231 nm and an accuracy of 88.61%. Overall, the results demonstrate that Taguchi DOE, coupled with RSM, is a reliable and efficient method for identifying the optimal parameter combinations to produce uniform, fine PBAT nanofibers intended for biomedical applications. © 2025 IOP Publishing Ltd. 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