Ferroelectric Polymer PVDF-Based Nanogenerator

This chapter deals with the development of ferroelectric polymer polyvinylidene fluoride (PVDF)-based nanogenerators. Due to its inherent flexibility, PVDF has been studied for application in nanogenerators. We first introduce PVDF and its copolymers, and briefly discuss their properties. Then, we discuss fabrication methods, including solution casting, spin coating, template-assisted method, electrospinning, thermal drawing, and dip coating. Using these methods, a wide variety of ferroelectric polymer structures can be fabricated. In addition to the performance enhancements provided by fabrication methods, the performance of PVDF-based nanogenerators has been improved by incorporating fillers that can alter the factors affecting the performance. Next, we review energy sources that can be exploited by PVDF-based nanogenerators to harvest electricity. The abundant energy sources in the environment include sound, wind flow, and thermal fluctuation. Finally, we discuss implantable PVDF-based nanogenerators. Another advantage of PVDF is its biocompatibility, which enables implantable nanogenerators. We believe that this chapter can also be helpful to researchers who study sensors and actuators as well as nanogenerators

Reducing time to discovery : materials and molecular modeling, imaging, informatics, and integration

This work was supported by the KAIST-funded Global Singularity Research Program for 2019 and 2020. J.C.A. acknowledges support from the National Science Foundation under Grant TRIPODS + X:RES-1839234 and the Nano/Human Interfaces Presidential Initiative. S.V.K.’s effort was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division and was performed at the Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), a U.S. Department of Energy, Office of Science User Facility.Multiscale and multimodal imaging of material structures and properties provides solid ground on which materials theory and design can flourish. Recently, KAIST announced 10 flagship research fields, which include KAIST Materials Revolution: Materials and Molecular Modeling, Imaging, Informatics and Integration (M3I3). The M3I3 initiative aims to reduce the time for the discovery, design and development of materials based on elucidating multiscale processing-structure-property relationship and materials hierarchy, which are to be quantified and understood through a combination of machine learning and scientific insights. In this review, we begin by introducing recent progress on related initiatives around the globe, such as the Materials Genome Initiative (U.S.), Materials Informatics (U.S.), the Materials Project (U.S.), the Open Quantum Materials Database (U.S.), Materials Research by Information Integration Initiative (Japan), Novel Materials Discovery (E.U.), the NOMAD repository (E.U.), Materials Scientific Data Sharing Network (China), Vom Materials Zur Innovation (Germany), and Creative Materials Discovery (Korea), and discuss the role of multiscale materials and molecular imaging combined with machine learning in realizing the vision of M3I3. Specifically, microscopies using photons, electrons, and physical probes will be revisited with a focus on the multiscale structural hierarchy, as well as structure-property relationships. Additionally, data mining from the literature combined with machine learning will be shown to be more efficient in finding the future direction of materials structures with improved properties than the classical approach. Examples of materials for applications in energy and information will be reviewed and discussed. A case study on the development of a Ni-Co-Mn cathode materials illustrates M3I3's approach to creating libraries of multiscale structure-property-processing relationships. We end with a future outlook toward recent developments in the field of M3I3.Peer reviewe

Influenced of electron density on plasmonic behavior of coupled AU nanostructures

Surface plasmon resonance has attracted extensive interest because it allows us to manipulate light in nanoscale which is of paramount importance for optoelectronic switching devices, information processing, biological and chemical sensing, particularly in the field of dynamic controlled device, which can be realized by in-situ charging the material via applying electric potential. In this dissertation, we focus on investigating the plasmonic far field (extinction spectra) and near field (field enhancement) properties of coupled nanostructure in response to charging effect. A Drude-Lorentz model can describes the charging effect on a material. By employing the dielectric constants with different amount of free electron density, we theoretically investigating the charging effects (increase of excess of electrons) on both isolated (monomer) and coupled (dimer) Au nanostructure. The Au dimers are constructed from sphere and ellipsoid monomers building blocks. The increase of charging level induces plasmon peak blue shifting. We find that plasmon shifting depends on the geometries of the nanostructure. Larger the geometrical factors, larger the plasmon shifts. Subsequently, we characterize the sensitivity from the slope of the plasmon shifts. As expected, ellipsoid-ellipsoid dimer exhibits the largest geometrical factor (5.41) among all nanostructures in this study and yields the largest plasmon shifts, thus has the highest far field sensitivity (-2.87) to the charging effect. The results calculate from numerical solution is in agreement with those from analytical solutions. We also have study the near field response to the charging effect for these coupled nanostructures. The near field can be characterized based on the average electric field enhancement factor of nanostructures. When increasing the excess electrons to the Au nanostructures, the enhancement spectra are blue shifted, the results are consistent with their far field counterpart. To quantify the sensitivity of the near field response to the charging effect, we calculate the enhancement ratio of each nanostructure as a function of different charging levels. Surprisingly, we find that the ellipsoid-ellipsoid dimer yields the lowest enhancement ratio among all nanostructures despite its largest value of enhancement factor, and shows the lowest sensitivity with the value of 0.48. This phenomenon is because of the strong distorted charges separation in the ellipsoid-ellipsoid dimer, which can be explained by the effective dipole moment model. To mimic the real system, we conduct a study on the charging effect on sphere-on-substrate. Attributing to the presence of substrate in close proximity, the plasmon band of Au sphere is broaden, which retards the plasmon shifting, hence lower far field sensitivity toward charging effect. Despite the lower value of enhancement factor, we find the sphere-on-substrate shows a comparable value of sensitivity as that of ellipsoid monomer. Overall, this work provides a guide in designing nanostructure, particularly in the sensing application. In addition, with this knowledge, we can extrapolate to other geometries such as nanoprism, nanobar, and their coupled structures.DOCTOR OF PHILOSOPHY (MSE

Mechanical and thermal properties of palm-based polyurethane composites filled with Fe3O4, PANI and PANI/Fe3O4

In-situ polymerization method was used to prepare palm-based polyurethane (PU) composites loading with 15 wt% magnetite (Fe3O4), polyaniline (PANI) and Fe3O4 coated with PANI labeled as PU15, PP and PPM, respectively. FTIR spectroscopy analysis indicated a shift in the carbonyl, C=O and NH in PP. The shift of the peak indicated that there was hydrogen bonding between the C=O (proton acceptor) of urethane with NH (proton-donator) of PANI. PPM gave the highest impact and flexural strengths at 4875 kJ/ m2 and 42 MPa, respectively but with the lowest flexural modulus (1050 MPa). Two-stage degradation behavior was observed in the TGA thermogram

Spatially probed plasmonic photothermic nanoheater enhanced hybrid polymeric – metallic PVDF‐Ag nanogenerator

Surface plasmon-based photonics offers exciting opportunities to enable fine control of the site, span, and extent of mechanical harvesting. However, the interaction between plasmonic photothermic and piezoresponse still remains underexplored. Here, spatially localized and controllable piezoresponse of a hybrid self-polarized polymeric-metallic system that correlates to plasmonic light-to-heat modulation of the local strain is demonstrated. The piezoresponse is associated to the localized plasmons that serve as efficient nanoheaters leading to self-regulated strain via thermal expansion of the electroactive polymer. Moreover, the finite-difference time-domain simulation and linear thermal model also deduce the local strain to the surface plasmon heat absorption. The distinct plasmonic photothermic-piezoelectric phenomenon mediates not only localized external stimulus light response but also enhances dynamic piezoelectric energy harvesting. The present work highlights a promising surface plasmon coordinated piezoelectric response which underpins energy localization and transfer for diversified design of unique photothermic-piezotronic technology.NRF (Natl Research Foundation, S’pore

Inverse Stellation of CuAu-ZnO Multimetallic-Semiconductor Nanostartube for Plasmon-Enhanced Photocatalysis

One-dimensional (1D) metallic nanocrystals constitute an important class of plasmonic materials for localization of light into subwavelength dimensions. Coupled with their intrinsic conductive properties and extended optical paths for light absorption, metallic nanowires are prevalent in light-harnessing applications. However, the transverse surface plasmon resonance (SPR) mode of traditional multiply twinned nanowires often suffers from weaker electric field enhancement due to its low degree of morphological curvature in comparison to other complex anisotropic nanocrystals. Herein, simultaneous anisotropic stellation and excavation of multiply twinned nanowires are demonstrated through a site-selective galvanic reaction for a pronounced manipulation of light–matter interaction. The introduction of longitudinal extrusions and cavitation along the nanowires leads to a significant enhancement in plasmon field with reduced quenching of localized surface plasmon resonance (LSPR). The as-synthesized multimetallic nanostartubes serve as a panchromatic plasmonic framework for incorporation of photocatalytic materials for plasmon-assisted solar fuel production

Surface Plasmon Resonance Enhanced Light Absorption and Photothermal Therapy in the Second Near-Infrared Window

Enhanced near-field at noble metal nanoparticle surfaces due to localized surface plasmon resonance (LSPR) has been researched in fields ranging from biomedical to photoelectrical applications. However, it is rarely explored on nonmetallic nanomaterials discovered in recent years, which can also support LSPR by doping-induced free charge carriers, let alone the investigation of an intricate system involving both. Here we construct a dual plasmonic hybrid nanosystem Au–Cu₉S₅ with well controlled interfaces to study the coupling effect of LSPR originating from the collective electron and hole oscillations. Cu₉S₅ LSPR is enhanced by 50% in the presence of Au, and the simulation results confirm the coupling effect and the enhanced local field as well as the optical power absorption on Cu₉S₅ surface. This enhanced optical absorption cross section, high photothermal transduction efficiency (37%), large light penetration depth at 1064 nm, excellent X-ray attenuation ability, and low cytotoxicity enable Au–Cu₉S₅ hybrids for robust photothermal therapy in the second near-infrared (NIR) window with low nanomaterial dose and laser flux, making them potential theranostic nanomaterials with X-ray CT imaging capability. This study will benefit future design and optimization of photoabsorbers and photothermal nanoheaters utilizing surface plasmon resonance enhancement phenomena for a broad range of applications

Reducing time to discovery:materials and molecular modeling, imaging, informatics, and integration

Multiscale and multimodal imaging of material structures and properties provides solid ground on which materials theory and design can flourish. Recently, KAIST announced 10 flagship research fields, which include KAIST Materials Revolution: Materials and Molecular Modeling, Imaging, Informatics and Integration (M3I3). The M3I3 initiative aims to reduce the time for the discovery, design and development of materials based on elucidating multiscale processing-structure-property relationship and materials hierarchy, which are to be quantified and understood through a combination of machine learning and scientific insights. In this review, we begin by introducing recent progress on related initiatives around the globe, such as the Materials Genome Initiative (U.S.), Materials Informatics (U.S.), the Materials Project (U.S.), the Open Quantum Materials Database (U.S.), Materials Research by Information Integration Initiative (Japan), Novel Materials Discovery (E.U.), the NOMAD repository (E.U.), Materials Scientific Data Sharing Network (China), Vom Materials Zur Innovation (Germany), and Creative Materials Discovery (Korea), and discuss the role of multiscale materials and molecular imaging combined with machine learning in realizing the vision of M3I3. Specifically, microscopies using photons, electrons, and physical probes will be revisited with a focus on the multiscale structural hierarchy, as well as structure-property relationships. Additionally, data mining from the literature combined with machine learning will be shown to be more efficient in finding the future direction of materials structures with improved properties than the classical approach. Examples of materials for applications in energy and information will be reviewed and discussed. A case study on the development of a Ni-Co-Mn cathode materials illustrates M3I3's approach to creating libraries of multiscale structure-property-processing relationships. We end with a future outlook toward recent developments in the field of M3I3.</p