Ultrahigh Capacitive Energy Density in Stratified 2D Nanofiller-Based Polymer Dielectric Films.

Dielectric capacitors are critical components in electronics and energy storage devices. The polymer-based dielectric capacitors have the advantages of device flexibility, fast charge-discharge rates, low loss, and graceful failure. Elevating the use of polymeric dielectric capacitors for advanced energy applications such as electric vehicles (EVs), however, requires significant enhancement of their energy densities.

Comparative Study of Polymer-Grafted BaTiO Nanoparticles Synthesized Using Normal ATRP as Well as ATRP and ARGET-ATRP with Sacrificial Initiator with a Focus on Controlling the Polymer Graft Density and Molecular Weight.

Structurally well-defined polymer-grafted nanoparticle hybrids are highly sought after for a variety of applications, such as antifouling, mechanical reinforcement, separations, and sensing. Herein, we report the synthesis of poly(methyl methacrylate) grafted- and poly(styrene) grafted-BaTiO nanoparticles using activator regeneration via electron transfer (ARGET ATRP) with a sacrificial initiator, atom transfer radical polymerization (normal ATRP), and ATRP with sacrificial initiator, to understand the role of the polymerization procedure in influencing the structure of nanoparticle hybrids. Irrespective of the polymerization procedure adopted for the synthesis of nanoparticle hybrids, we noticed PS grafted on the nanoparticles showed moderation in molecular weight and graft density (ranging from 30,400 to 83,900 g/mol and 0.

Polymer-Grafted Nanoparticles with Variable Grafting Densities for High Energy Density Polymeric Nanocomposite Dielectric Capacitors.

Designing high energy density dielectric capacitors for advanced energy storage systems needs nanocomposite-based dielectric materials, which can utilize the properties of both inorganic and polymeric materials. Polymer-grafted nanoparticle (PGNP)-based nanocomposites alleviate the problems of poor nanocomposite properties by providing synergistic control over nanoparticle and polymer properties. Here, we synthesize "core-shell" barium titanate-poly(methyl methacrylate) (BaTiO-PMMA) grafted PGNPs using surface-initiated atom transfer polymerization (SI-ATRP) with variable grafting densities of (0.

Enhanced Dielectric Strength and Capacitive Energy Density of Cyclic Polystyrene Films.

The maximum capacitive energy stored in polymeric dielectric capacitors, which are ubiquitous in high-power-density devices, is dictated by the dielectric breakdown strength of the dielectric polymer. The fundamental mechanisms of the dielectric breakdown, however, remain unclear. Based on a simple free-volume model of the polymer fluid state, we hypothesized that the free ends of linear polymer chains might act as "defect" sites, at which the dielectric breakdown can initiate.

Correction to "An Investigation of the Interaction Between Bovine Serum Albumin-Conjugated Silver Nanoparticles and the Hydrogel in Hydrogel Nanocomposites".

[This corrects the article DOI: 10.1021/acsomega.1c00834.

Recent Advances in the Synthesis of Polymer-Grafted Low-K and High-K Nanoparticles for Dielectric and Electronic Applications.

The synthesis of polymer-grafted nanoparticles (PGNPs) or hairy nanoparticles (HNPs) by tethering of polymer chains to the surface of nanoparticles is an important technique to obtain nanostructured hybrid materials that have been widely used in the formulation of advanced polymer nanocomposites. Ceramic-based polymer nanocomposites integrate key attributes of polymer and ceramic nanomaterial to improve the dielectric properties such as breakdown strength, energy density and dielectric loss. This review describes the "grafting from" and "grafting to" approaches commonly adopted to graft polymer chains on NPs pertaining to nano-dielectrics.

An Investigation of the Interaction between Bovine Serum Albumin-Conjugated Silver Nanoparticles and the Hydrogel in Hydrogel Nanocomposites.

Nanocomposite hydrogels are attracting significant interest due to their potential use in drug delivery systems and tissue scaffolds. Stimuli-responsive hydrogel nanocomposites are of particular interest due to sustained release of therapeutic agents from the hydrogel. However, challenges such as controlled release of therapeutic agents exist because of limited understanding of the interactions between the therapeutic agent and the hydrogel.

Recent developments in the synthesis of chemically modified nanomaterials for use in dielectric and electronics applications.

Polymer nanocomposites (PNC) have attracted enormous scientific and technological interest due to their applications in energy storage, electronics, biosensing, drug delivery, cosmetics and packaging industry. Nanomaterials (platelet, fibers, spheroids, whiskers, rods) dispersed in different types of polymer matrices constitute such PNC. The degree of dispersion of the inorganic nanomaterials in the polymer matrix, as well as the structured arrangement of the nanomaterials, are some of the key factors influencing the overall performance of the nanocomposite.

High broadband photoconductivity of few-layered MoS field-effect transistors measured using multi-terminal methods: effects of contact resistance.

Among the layered two dimensional semiconductors, molybdenum disulfide (MoS2) is considered to be an excellent candidate for applications in optoelectronics and integrated circuits due to its layer-dependent tunable bandgap in the visible region, high ON/OFF current ratio in field-effect transistors (FET) and strong light-matter interaction properties. In this study, using multi-terminal measurements, we report high broadband photocurrent response (R) and external quantum efficiency (EQE) of few-atomic layered MoS2 phototransistors fabricated on a SiO2 dielectric substrate and encapsulated with a thin transparent polymer film of Cytop. The photocurrent response was measured using a white light source as well as a monochromatic light of wavelength λ = 400 nm-900 nm.

Effect of Molecular Weight and Layer Thickness on the Dielectric Breakdown Strength of Neat and Homopolymer Swollen Lamellar Block Copolymer Films.

Designing next-generation lightweight pulsed power devices hinges on understanding the factors influencing the energy storage performance of dielectric materials. Polymer dielectric films have a quadratic dependence of energy storage on the voltage breakdown strength, and strategies to enhance the breakdown strength are expected to yield a path toward high energy storage densities. Highly stratified lamellar block copolymer (L-BCP) films of model polystyrene--polymethylmethacrylate (PS-b-PMMA) exhibited as much as ~50% enhancement in breakdown voltage ( ) (225% increase in stored energy density, ) compared to unordered as-cast L-BCP films.

Tuning the Relaxation of Nanopatterned Polymer Films with Polymer-Grafted Nanoparticles: Observation of Entropy-Enthalpy Compensation.

Polymer films provide a versatile platform in which complex functional relief patterns can be thermally imprinted with a resolution down to few nanometers. However, a practical limitation of this method is the tendency for the imprinted patterns to relax ("slump"), leading to loss of pattern fidelity over time. While increasing temperature above glass transition temperature ( T) accelerates the slumping kinetics of neat films, we find that the addition of polymer-grafted nanoparticles (PGNP) can greatly enhance the thermal stability of these patterns.

Confined Pattern-Directed Assembly of Polymer-Grafted Nanoparticles in a Phase Separating Blend with a Homopolymer Matrix.

The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We show that the phase separation of polymer-tethered nanoparticles immersed in a chemically different polymer matrix provides an effective and scalable method for fabricating defined submicron-sized amorphous NP domains in melt polymer thin films. We investigate this phenomenon with a view towards understanding and controlling the phase separation process through directed nanoparticle assembly.

Directed Self-Assembly of Block Copolymers for High Breakdown Strength Polymer Film Capacitors.

Emerging needs for fast charge/discharge yet high-power, lightweight, and flexible electronics requires the use of polymer-film-based solid-state capacitors with high energy densities. Fast charge/discharge rates of film capacitors on the order of microseconds are not achievable with slower charging conventional batteries, supercapacitors and related hybrid technologies. However, the current energy densities of polymer film capacitors fall short of rising demand, and could be significantly enhanced by increasing the breakdown strength (EBD) and dielectric permittivity (εr) of the polymer films.

Antimicrobial and cell viability measurement of bovine serum albumin capped silver nanoparticles (Ag/BSA) loaded collagen immobilized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) film.

Bacterial infection of orthopedic devices has been a major concern in joint replacement procedures. Therefore, this study is aimed at formulating collagen immobilized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) film loaded with bovine serum albumin capped silver nanoparticles (Ag/BSA NPs) to inhibit bacterial growth while retaining/promoting osteoblast cells viability. The nanoparticles loaded collagen immobilized PHBV film was characterized for its composition by X-ray Photoelectron Spectroscopy and Anodic Stripping Voltammetry.

Dispersion morphology and correlation to moduli using buckling metrology in clay-biopolymer nanocomposite thin films.

Structure-interaction-mechanical property correlation in bionanocomposite thin films is an area of growing interest for research and application areas from barrier to molecular transport to UV blocking layers for polymer solar cells to dielectric properties modification. Here we study flow coated ultrathin to thin films (70-150 nm) of clay bionanocomposites to understand the nanoparticle dispersion and its effect on nanomechanical properties. Binary and ternary thin film systems of polylactide (PLA), polycaprolactone (PCL), and Cloisite 30B (C30B) clay platelets were investigated.

Synthesis and characterization of collagen grafted poly(hydroxybutyrate-valerate) (PHBV) scaffold for loading of bovine serum albumin capped silver (Ag/BSA) nanoparticles in the potential use of tissue engineering application.

The objective of this study is to synthesize and characterize collagen grafted poly(3-hydroxylbutyrate-co-3-hydroxylvalerate) (PHBV) film for loading of BSA capped silver (Ag/BSA) nanoparticles. Thermal radical copolymerization and aminolysis methods were used to functionalize macroporous PHBV, followed by collagen grafting so as to formulate collagen-g-poly(hydroxyethylmethyl acrylate)-g-poly(3-hydroxylbutyrate-co-3-hydroxylvalerate) [collagen-g-PHEMA-g-PHBV] and collagen-g-aminated-poly(3-hydroxylbutyrate-co-3-hydroxylvalerate) [collagen-g-NH2-PHBV] films, respectively. Spectroscopic (FTIR, XPS), physical (SEM), and thermal (TGA) techniques were used to characterize the functionalized PHBV films.

SPR studies of the adsorption of silver/bovine serum albumin nanoparticles (Ag/BSA NPs) onto the model biological substrates.

The primary objective of this study is to investigate the interactive forces that promote the adsorption of bio-conjugated nanoparticles onto proteins. To elucidate the interactive forces, we demonstrate an approach using synthetic and model biological surfaces to study adsorption of bio-conjugated nanoparticles. Real-time adsorption of BSA conjugated silver nanoparticles (Ag/BSA NPs) on the immobilized substrates was followed by surface plasmon resonance (SPR).

Adsorption-desorption study of BSA conjugated silver nanoparticles (Ag/BSA NPs) on collagen immobilized substrates.

There has been a growing interest in the use of protein conjugated nanoparticles for applications in biomedical, sensing, and advanced imaging. The objective of this study was to understand the interaction of protein conjugated silver nanoparticles (Ag/BSA NPs) with biological substrate (collagen layer). The adsorption behavior of synthesized Ag/BSA NPs on collagen immobilized silanized surface was followed by UV-vis spectroscopy by initially studying the formation of collagen layer and subsequent adsorption of Ag/BSA NPs to the immobilized layer.

Characterization of non-equilibrium nanoparticle adsorption on a model biological substrate.

The kinetics of nanoparticle (NP) adsorption on a model biological interface (collagen) is measured in microfluidic channels using surface plasmon resonance (SPR) imaging over a range of CdSe/ZnS quantum dot concentrations to investigate the underlying binding process. Spherical CdSe/ZnS core-shell NP, derivatized with 3-mercaptopropionic acid (3-MPA), were considered to be model NPs because of their widespread use in biological applications and their relatively monodisperse size. The kinetic adsorption data suggests that the binding between the NP and the collagen substrate is irreversible at room temperature (pH approximately 7.

Biological response of osteoblast-like UMR-106 cells to the modified PHBV matrix--effects of porosity and collagen dip coating.

In this study, we related porosity and collagen coating of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) scaffold to the degree of cell proliferation on the engineered PHBV scaffold. Based on the [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2h-tetrazolium, inner salt] (MTS) assay, we established that UMR-106 cell proliferation is maximum in collagen-coated porous PHBV film followed by porous PHBV film and least in nonporous PHBV film. RT-PCR analysis of the proliferated cells on tissue culture polystyrene (TCPS) and porous and nonporous PHBV scaffolds revealed that the proliferated cells retained their osteoblastic phenotype characteristics.

Langmuir adsorption study of the interaction of CdSe/ZnS quantum dots with model substrates: influence of substrate surface chemistry and pH.

We investigate the utility of Langmuir adsorption measurements for characterizing nanoparticle-substrate interactions. Spherical CdSe/ZnS core-shell nanoparticles were chosen as representative particles because of their widespread use in biological labeling measurements and their relatively monodisperse dimensions. In particular, the quantum dots were functionalized with 11-mercaptoundecanoic acid, and we utilized an amine-terminated self-assembled monolayer (SAM) as a model substrate.

Seasonal variation of heavy metals in ambient air and precipitation at a single site in Washington, DC.

Atmospheric samples of precipitation and ambient air were collected at a single site in Washington, DC, for 7 months (for ambient air samples) and 1 year (for wet deposition samples) and analyzed for arsenic, cadmium, chromium and lead. The ranges of heavy metal concentrations for 6-day wet deposition samples collected over the 1-year period were 0.20-1.

Evaluation of the biological responses of osteoblast-like UMR-106 cells to the engineered porous PHBV matrix.

Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) has been investigated for biomedical applications due to its many biologically favorable properties. However, to explore its application in bone tissue engineering, the poorly bioactive surface property of PHBV must be improved. To engineer PHBV to achieve a biologically active surface, in this study each porous PHBV matrix was prepared by solute leaching of salt/PHBV cast film and was treated with ozone followed by dip coating with type I collagen.