Particle Surface Chemistry Research Articles

Protective effect of sodium stearate on the moisture-induced deterioration of hygroscopic spray-dried powders

Amorphous powders are thermodynamically unstable, significantly impacting the processing, storage and performance of a product. Therefore, stabilization of the amorphous contents is in demand. In this study, disodium cromoglycate (DSCG) powder was chosen as a model drug because it is amorphous and highly hygroscopic after spray drying. Sodium stearate (NaSt) was co-spray dried with DSCG at various concentrations (10, 50 and 90% w/w) to investigate its effect against moisture-induced deterioration on the in vitro aerosolization performance of DSCG. Particle size distribution and morphology were measured by laser diffraction and scanning electron microscopy (SEM). Physicochemical properties of the powders were analysed by X-ray powder diffraction (XRPD) and dynamic vapour sorption (DVS). Particle surface chemistry was analysed by the time-of-flight secondary ion mass spectrometry (ToF-SIMS). In vitro dissolution behaviours of the spray-dried (SD) powders were tested by the Franz cell apparatus. In vitro aerosolization performance of SD formulations stored at different relative humidity (RH) was evaluated by a multi-stage liquid impinger (MSLI), using an Osmohaler® at 100 L/min. Results showed that adding NaSt in the formulation not only increased the aerosolization performance of DSCG significantly, but also effectively reduced the deleterious impact of moisture. No significant difference was found in the fine particle fraction (FPF) of formulations containing NaSt before and after storage at both 60% and 75% RH for one week. However, after one month storage at 75% RH, SD formulation containing 10% NaSt showed a reduction in FPF, while formulations containing 50% or 90% NaSt showed no change. The underlying mechanism was that NaSt increased the crystallinity of the powders and its presence on the particle surface reduced particle aggregations and cohesiveness. However, NaSt at high concentration could reduce dissolution rate, which needs to be taken into consideration.

Design of Pickering Micro- and Nanoemulsions Based on the Structural Characteristics of Nanocelluloses.

The development of biobased materials with lower environmental impact has seen an increased interest these last years. In this area, nanocelluloses have shown a particular interest in research and industries. Cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) are both known to stabilize oil-water interfaces, forming the so-called Pickering emulsions which are surfactant-free, highly stable emulsions armored by a layer of solid particles. This work describes the emulsion's characteristics and properties according to particle size, shape and surface chemistry in order to produce controlled micro- and nanoemulsions stabilized by nanocelluloses. For this purpose, four nanocelluloses which vary in source, length, width, and surface charge density were used. Isolated droplets were produced by CNCs and interconnected droplets by CNFs that led to distinct drop size (micro- and nanosized), organization of nanoparticles at the surface of the droplets, stability, and mechanical properties through rheological measurements. This work gives a precise description of the resulting emulsions and shows the ability to produce nanosized droplets for CNC and TEMPO oxidized CNF but not for the less fibrillated CNF using HP-homogenizer. Individual noncreaming droplets with average diameters as low as 350 nm were achieved for cotton CNCs and TEMPO oxidized CNFs.

Nanoscale Janus Particles with Dual Protein Functionalization

AbstractBiofunctionalized Janus particles with tailored surface chemistry are gathering interest for applications as catalysts, multifunctional cell surface targets, nanomotors, and drug delivery systems. The dual nature of the surface chemistry of Janus particles can be exploited to immobilize drugs, cell surface targets, and/or other functional molecules on both sides of the particle surface. In this study, a model system is established for the scalable preparation of nanoscale Janus particles with dual protein functionalization with the proteins ferritin and streptavidin. 80 nm silica nanoparticles (SiNPs) modified with azidosilane are used to prepare Pickering emulsions with molten wax as the droplet phase. The azide‐functionalized SiNPs on the Pickering emulsion droplets are further subjected to face‐selective silanization with biotin‐polyethylene glycol ethoxy silane. Afterward, ferritin is grafted on the azide‐functionalized side via a click‐reaction and the biotin groups are conjugated with streptavidin which is labeled with ultrasmall gold nanoparticles. In order to elucidate the advantages and limits of this approach, a detailed characterization is performed of the particles at every process step. The results show that this method represents a scalable platform for the versatile preparation of nanoscale Janus nanoparticles that can potentially be used with a wide variety of proteins.

Current characterization methods for cellulose nanomaterials.

A new family of materials comprised of cellulose, cellulose nanomaterials (CNMs), having properties and functionalities distinct from molecular cellulose and wood pulp, is being developed for applications that were once thought impossible for cellulosic materials. Commercialization, paralleled by research in this field, is fueled by the unique combination of characteristics, such as high on-axis stiffness, sustainability, scalability, and mechanical reinforcement of a wide variety of materials, leading to their utility across a broad spectrum of high-performance material applications. However, with this exponential growth in interest/activity, the development of measurement protocols necessary for consistent, reliable and accurate materials characterization has been outpaced. These protocols, developed in the broader research community, are critical for the advancement in understanding, process optimization, and utilization of CNMs in materials development. This review establishes detailed best practices, methods and techniques for characterizing CNM particle morphology, surface chemistry, surface charge, purity, crystallinity, rheological properties, mechanical properties, and toxicity for two distinct forms of CNMs: cellulose nanocrystals and cellulose nanofibrils.

Distinct dispersion stability of various TiO2 nanopowders using ammonium polyacrylate as dispersant

The dispersion stabilities of three titania (TiO2) nanopowders with different particle sizes and surface chemistries in aqueous suspensions containing a common water-based dispersant, ammonium polyacrylate (PAA-NH4), have been investigated and compared. According to adsorption isotherm and Fourier transform infrared spectroscopy analyses, the adsorption conformations of PAA-NH4 are distinct for the different TiO2 nanopowders. In addition, PAA-NH4 exhibited the greatest adsorption affinity to the larger, hydrophilic TiO2 nanopowder and the least affinity to smaller, hydrophobic nanopowder. From sedimentation and rheological results, the dispersion stability of the larger, hydrophilic TiO2 nanopowder was demonstrated to be the greatest. Based on thermodynamic and kinetic calculations for the stabilization energies, the larger, hydrophilic TiO2 nanopowder was also shown to be the best-stabilized powder, although it settles faster than the smaller, hydrophilic TiO2 nanopowder; this is due to the greater affection of sedimentation flux on the larger nanopowder. In contrast, the hydrophobic TiO2 nanopowder formed a gel-like structure in the aqueous suspension when the solid content was greater than 10wt%, which is attributed to polymer bridging between PAA-NH4-adsorbed TiO2 nanoparticles.

Development of reference metal and metal oxide engineered nanomaterials for nanotoxicology research using high throughput and precision flame spray synthesis approaches

There is a growing need to develop and characterize reference metal and metal oxide engineered nanomaterials (ENMs) of high purity and tunable intrinsic properties suitable for nanotoxicology research. Here a high throughput (volume) and precision flame spray pyrolysis (FSP) approach coupled with state-of-the-art characterization techniques are utilized to generate such reference ENMs. The lab-based and industrially relevant FSP system, termed as Versatile Engineered Nanomaterials Generation System (VENGES), synthesizes the metals and metal oxides, at high throughput manner with controlled properties, such as primary particle size, aggregate diameter, shape, crystallinity, stoichiometry and surface chemistry. A nanopanel of nine reference ENMs (silica, silver, silver supported on silica, alumina, ceria and iron oxide) was synthesized and characterized using combined electron microscopy, advanced spectroscopic techniques and physical analyses (e.g., BET, XRD, TEM, pycnometry, XPS, ICP-MS and FTIR). ENMs show a high degree of chemical purity and stoichiometry, and low content of carbon residuals, and are sterile and free of bacteria and endotoxins. Further, their colloidal properties and their implication in in-vitro dosimetry have been also investigated in both environmental and test biological media. The suitability of reference ENMs and protocols developed in this study brings forth new arenas to generate reliable and reproducible toxicological data in an effort to reduce conflicting and contradicting inter-laboratory data on relative toxic effects of ENMs.

Effects of surface modification and size on oral drug delivery of mesoporous silica formulation

The surface chemistry and size of nanoparticles can greatly impact their interaction with biological pathways and alter efficacy. However, the interplay between surface modification and particle size has not been well investigated especially for oral delivery. It is necessary to maximize the bioavailability of loading therapeutics. Here, we prepared different sized mesoporous silica nanoparticles (100–500 nm) and conjugated them with polyethylenimine-coated carbondots (PCD) for effective transepithelial absorption. The nanoparticles were also coated with polyethylene glycol (PEG) polymers for improved mucus permeability. These mesoporous silica nanoparticles conjugated to PCD and coated in PEG (MSN@PCD@PEG) were used to study the influence of particle size and surface chemistry on transepithelial transport and bioavailability. Results demonstrated that the MSN@PCD@PEG with a diameter 250 nm had the highest transepithelial transport and oral bioavailability compared to other formulations. Drug release, endocytosis pathways, transepithelial transport and degradation of these different nanocarriers were systematically studied in order to investigate effects of size variety. The findings indicated that nanoparticle-based oral drug delivery can be potentially improved by adjusting physicochemical properties. We believe that understanding the importance of surface chemistry and particle size in the oral delivery will improve nanoparticle engineering and oral application.

Efficient filtration of micron and submicron particles by ascidians from oligotrophic waters

AbstractSuspended food particles in oligotrophic waters are scarce and the planktonic community is dominated by minute picoplanktonic (< 2 μm) cells. Consequently, suspension feeders inhabiting such environments are faced with the dual challenge of capturing extremely small particles and efficiently processing large volumes of water. We used direct in situ techniques to characterize the size‐dependent capture efficiency curve of four solitary ascidian species (Chordata, Tunicata) from the ultra‐oligotrophic East‐Mediterranean, and two species from the oligotrophic Gulf of Aqaba (Northern Red‐Sea). To control for confounding factors such as particle surface chemistry, we used a suspension of artificial polystyrene microspheres with a wide range of sizes (from 0.3 μm to 10 μm) but identical surface chemistry. This suspension was introduced into the inhalant siphon while the water inhaled and exhaled by the otherwise undisturbed ascidian was cleanly sampled. All the investigated ascidian species captured ≥ 1 μm microspheres at 95% ± 8% efficiency (mean ± 95% Confidence Interval) with no significant difference between species. Moreover, and in contrast to reports from eutrophic waters, both in situ and laboratory experiments revealed an efficient capture of submicron 0.3 μm microspheres at close to 50% efficiency. For most of the species tested, the capture efficiency of microspheres dropped below optimum between 1 μm and 0.5 μm providing an estimation of their mucus mesh pore size. We suggest that ascidians from oligotrophic waters are adapted for capturing submicron particles picoplankton and other. Such adaptation enables “oligotrophic” ascidians to access a much larger food source and facilitates the transfer of planktonic C, N, and P from the water column to the benthos.

Modulating the Lipase‐Mediated Bioactivity of Particle‐Lipid Conjugates Through Changes in Nanostructure and Surface Chemistry

The lipase‐mediated hydrolysis of triglycerides can be controlled by confining lipid droplets within highly porous nanostructured particle matrices. Novel hybrid materials with varying bioactivities toward lipase have been developed by spray drying particle‐stabilized emulsions to form highly organized three‐dimensional architectures. In this study, the particle size, nanostructure, and surface chemistry of hybrid particles are tailored to systematically investigate the influence of material characteristics on lipase activity. This is achieved by varying (i) the spray drying process and (ii) the structure and composition of particulate colloids employed to stabilize the precursor emulsions. In all cases, the colloidal self‐assembly of particles and droplets into nanostructured conjugates during the water removal process facilitated enhanced lipase activity compared to submicron triglyceride emulsions, with lipolysis kinetics increasing in the following order: polymer‐lipid hybrid (PLH) < silica‐lipid hybrid (SLH) ≤ clay‐lipid hybrid (CLH). Lipase activity increased as a function of increasing interfacial surface area of the lipid substrate and increasing hydrophilicity of the solid matrix support. The novel insights into the role of hybrid particle nanostructure and surface chemistry on the mechanism of lipase action can be harnessed for the intelligent design of new and improved lipid‐based drug delivery vehicles and functional foods.Practical Applications: Understanding and controlling the interaction between triglyceride molecules and pancreatic lipase is of fundamental importance for the rational design of new functional foods and drug formulations. Lipid digestion in the body facilitates the delivery of fat and encapsulated bioactive compounds from the gastrointestinal tract (GIT) to the blood and surrounding tissues. Hence, the bioavailability of poorly soluble compounds can be controlled by engineering lipid‐based systems that regulate lipase activity. In this study, three novel solid‐state systems have been designed that finely control the catalytic activity of lipase, and therefore, demonstrate high commercial potential within the pharmaceutical and biotechnology industries.The lipase‐mediated hydrolysis of triglycerides is controlled by designing novel solid‐state particle‐lipid conjugates with unique nanostructures and surface chemistries. The hybrid materials are prepared by spray‐drying particle‐stabilized lipid droplets, which induced the forced agglomeration of particles and droplets into micron‐sized particles with distinctive three‐dimensional architectures. The ability to modulate lipase activity through material design presented novel insights into the mechanism of digestive enzyme action, which is of fundamental importance for the rational design of new functional foods and drug formulations.

Surface engineered nanoparticles dispersed in kerosene: The effect of oleophobicity on droplet combustion

Liquid propellants benefit from solid particle additives that can optimize combustion performance by promoting phase change heat transfer. In this study, aluminum (Al) nanoparticles with and without self-assembled monolayer surface functionalization were combined with kerosene to examine the changes in droplet regression behavior associated with manipulating particle surface chemistry. Aluminum nanoparticles were coated using a long-chain perfluorinated carboxylic acid as the surface binding moiety to induce an oleophobic surface. The resulting particles are thus comprised of self-assembled monolayers of perfluorohexadecanoic acid (PFHD) (C15F31COOH) around the alumina (Al2O3) shell encapsulating the Al core. The PFHD serves many functions including altering particle wettability and acting as a surfactant that facilitates a stabilized dispersion of particles in kerosene. The Al-PFHD particles are more oleophobic compared with the more oleophilic surface associated with the amorphous alumina shell on aluminum particles. Mixtures with Al-PFHD exhibit a two stage burning behavior with average initial burn rate constant increased by about 121% when compared to pure kerosene. Further analysis using a thermogravimetric analyzer (TGA) showed that Al-PFHD particles in kerosene exhibit evaporation at reduced temperatures that may enhance energy transport during droplet combustion by phase change and convection. These results provide new insight bridging the gap between materials and heat transfer toward achieving the goal of designing particle additives that improve liquid propellant combustion.

Estimated depth of apatite and collagen degradation in human dentine by sequential exposure to sodium hypochlorite and EDTA: a quantitative FTIR study.

To characterize chemical degradation of the principal constituents of dentine after exposure to NaOCl and EDTA using Infrared Spectroscopy (ATR-FTIR). Ground dentine particles, from extracted permanent human molars, were passed through sieves of 38 to 1000μm to provide six size ranges. Portions (250mg) of each size range were reacted with 5mL of 2.5% NaOCl for 2-10min; or 17% EDTA for 5-1440min. Powders larger than 75μm were also sequentially exposed to NaOCl/EDTA/NaOCl each for 10min. All experiments were repeated five times. Reacted and unreacted powders were washed and dried. Particles larger than 75μm were then reground. FTIR spectra of unground and reground reacted particles enabled assessment of particle surface versus bulk chemistry, respectively, plus estimation of reaction depth. Changes in the ratio of the 1640cm-1 collagen: 1010cm-1 phosphate peak height or its inverse were obtained. These were used to estimate surface and bulk fraction reacted and thus depth to which collagen or phosphate was reduced following immersion in NaOCl or EDTA, respectively. The data were analysed descriptively. Surface collagen fraction declined by ~40% within 2min of NaOCl exposure, and plateaued at ~60% between 6-10min. Bulk spectra showed average depth of collagen loss at 10min was 16±13μm. Ten minute EDTA exposure caused ~60% loss of surface phosphate. Average depth of phosphate loss was 19±12μm and 89±43μm after 10 and 1440min EDTA immersion, respectively. Sequential NaOCl/EDTA immersion yielded a 62±28μm thick phosphate-depleted surface. Sequential NaOCl/EDTA/NaOCl treatment resulted in approximately 85μm of collagen loss. Data revealed the sequential depletion of collagen by NaOCl and apatite by EDTA in dentine, simultaneously exposing the other moieties. Alternate exposure to NaOCl and EDTA therefore enhances the depth of erosion.

Nebulised antibiotherapy: conventional versus nanotechnology-based approaches, is targeting at a nano scale a difficult subject?

Nebulised antibiotics offer great advantages over intravenously administered antibiotics and other conventional antibiotic formulations. However, their use is not widely standardized in the current clinical practice. This is the consequence of large variability in the performance of nebulisers, patient compliance and a deficiency of robust preclinical and clinical data. Nebulised antibiotherapy may play a significant role in future pulmonary drug delivery treatments as it offers the potential to achieve both a high local drug concentration and a lower systemic toxicity. In this review, the physicochemical parameters required for optimal deposition to the lung in addition to the main characteristics of currently available formulations and nebuliser types are discussed. Particular attention will be focused on emerging nanotechnology based approaches which are revolutionizing inhaled therapies used to treat both infections and lung cancer. Promising carriers such as Trojan-Horse microparticles, liposomes, polymeric and lipid nanoparticulate systems have been investigated and proposed as viable options. In order to achieve site-specific targeting and to optimize the PK/PD balance critical nanoscale design parameters such as particle size, morphology, composition, rigidity and surface chemistry architecture must be controlled. Development of novel excipients to manufacture these nanomedicines and assessment of their toxicity is also a keystone and will be discussed in this review.

Analysis Gunshot Residue (GSR) – Reconstruction of Crime Scenes

GSR particles from the surroundings of bullet hole have been characterized as a function of primer type and particle distribution. SEM images were used to verify size and shape of the GSR particles and EDS to verify the elemental composition in a single particle. The same specimens are further subjected toTime of Flight Secondary Ion Mass Spectrometry (ToF SIMS) with a view to identify the respective surface chemistry, molecular nature and molecular mass of the GSR particles. Both inorganic and organic components of GSR in the elemental and combined form can be identified using SIMS.Secondary ion mass spectrum and the image analysis are carried out for selected particles. The mass peaks of oxides of lead, barium and antimony apart from the elemental masses are found. The combination of Pb/Ba/Sb and their oxides in a particular particle specifically establish the characteristics of a typical GSR particle. Molecular imaging and the distribution of the components in the GSR particle before and after sputtering are studied. Lead and its oxide are more concentrated in the surface of the particle compared to Ba and Sb. It is evident that SIMS can detect whether the components are either in the elemental or a compound form or a combination of both. The results of ToF SIMS clearly establish the feasibility of utilizing ToF SIMS as a tool for direct characterization of GSR from environmental polluted particles of the same nature for forensic applications.

Gas Bubbles Stabilized by Janus Particles with Varying Hydrophilic-Hydrophobic Surface Characteristics.

Micrometer-sized polymer-grafted gold-silica (Au-SiO2) Janus particles were fabricated by vacuum evaporation followed by polymer grafting. The Janus particle diameter, diameter distribution, morphology, surface chemistry, and water wettability were characterized by optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The optical microscopy results showed that the polystyrene (PS)-grafted Au-SiO2 Janus particles exhibited monolayer adsorption at the air-water interface and could stabilize bubbles, preventing their coalescence for more than 1 month. The hydrophobic PS-grafted Au and hydrophilic SiO2 surfaces were exposed to the air and water phases, respectively. Bare Au-SiO2 and poly(2-(perfluorobutyl)ethyl methacrylate) (PPFBEM)-grafted Au-SiO2 Janus particles could also stabilize bubbles for up to 2 weeks. By contrast, bare silica particles did not stabilize bubbles and were dispersed in water. The bubbles that formed in the PS-grafted Janus particle system were more stable than those formed in the bare Au-SiO2 Janus particles, PPFBEM-grafted Au-SiO2 Janus particles, and SiO2 particle systems because of the high adsorption energy of the PS-grafted particles at the air-water interface.

The effects of hydration on the DC breakdown strength of polyethylene composites employing oxide and nitride fillers

Particle dispersion, water absorption/desorption and electrical breakdown behavior were studied in a range of polyethylene composites having a common matrix morphology. Three different conditioning routes (dry, ambient and wet) were used to vary the absorbed water content. Systems employing oxide fillers (silica and alumina) were found to have poor or intermediate levels of particle dispersion and could absorb/desorb significant amounts of water. Consequently, they required drying to provide breakdown strengths comparable to that of the host matrix. Systems based on calcined silica exhibited reduced water absorption and provided improved breakdown strength after ambient conditioning, despite having an identical dispersion to those utilizing untreated silica. Composites employing nitride fillers (silicon nitride and aluminum nitride) were found to have good or intermediate levels of particle dispersion. These absorbed far less water and hence provided breakdown strength values comparable to that of the host matrix following ambient conditioning. Their breakdown strength was degraded after wet conditioning with both exhibiting similar breakdown strengths despite there being a large difference in the level of particle dispersion between the two fillers. In composites based upon a hydrophobic host matrix, water absorption is largely determined by particle surface chemistry and, although the above results are presented in terms of water absorption, we suggest that changes in this characteristic can be interpreted as a proxy for changed surface chemistry. The results suggest that surface chemistry is at least as important as particle dispersion in determining the electrical breakdown strength.

Radiofrequency electric field hyperthermia with gold nanostructures: role of particle shape and surface chemistry

Hyperthermia treatment of cancerous cells has been recently developed drastically with the help of nanostructures. Heating of gold nanoparticles in non-invasive radiofrequency electric field (RF-EF) is a promising and unique technique for cancer hyperthermia. However, because of differences between particles (i.e. their surface chemistry and dispersion medium) and between RF-EF sources, the research community has not reached a consensus yet. Here, we report the results of investigations on heating of gold nanoparticles and gold nanorods under RF-EF and feasibility of in-vitro cancer hyperthermia. The heating experiments were performed to investigate the role of particle shape and surface chemistry (CTAB, citrate and PEG molecules). In-vitro hyperthermia was performed on human pancreatic cancer cell (MIA Paca-2) with PEG-coated GNPs and GNRs at concentrations that were found non-toxic based on the results of cytotoxicity assay. Application of RF-EF on cells treated with PEG-GNPs and PEG-GNRs proved highly effective in killing cells.

Engineering PLGA nano-based systems through understanding the influence of nanoparticle properties and cell-penetrating peptides for cochlear drug delivery

The properties of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) and penetration enhancers play a deciding role in the inner ear drug delivery of NPs across the round window membrane (RWM). Thus, PLGA nano-based systems with a variety of particle sizes and surface chemistries and those combined with cell-penetrating peptides (CPPs) as penetration enhancers were devised to explore their impact on the cochlear drug delivery in vivo. First, we demonstrated that the properties of NPs dictated the extent of NP cochlear entry by near-infrared fluorescence imaging. NPs with the sizes of 150 and 300nm had faster entry than that of 80nm NPs. At 0.5h, among the NPs unmodified and modified with chitosan (CS), poloxamer 407 (P407) and methoxy polyethylene glycol, CS-PLGA-NPs (positive surface charge) carried payload to the cochlea fastest, whereas P407-PLGA-NPs (surface hydrophilicity) showed the greatest distribution in the cochlea at 24h. Compared to other CPPs (TAT, penetratin and poly(arginine)8), low molecular weight protamine (LMWP) performed an outstanding enhanced NP cellular uptake in HEI-OC1 cells and cochlear entry. More importantly, NPs with optimized properties and CPPs may be combined to improve RWM penetration. For the first time, we confirmed that the combination of P407-PLGA-NPs (mean diameter: 100–200nm) and LMWP provided a synergistic enhancement in NP entry to the organ of Corti and stria vascularis without inducing pathological alteration of cochlear tissues and RWM. Taken together, we propose an effective PLGA nano-based strategy for enhanced drug delivery to the inner ear tissues that combines hydrophilic molecule-modified NPs and CPPs, ultimately opening an avenue for superior inner ear therapy.

Superior Shelf Life and Moisture Tolerance of ALD-Coated Cathode Materials As Important Aspect of ALD-Based Improvements of Li-Ion Cell Cycle Life

Lithium-ion battery-based energy storage is widely regarded as the best technology to realize affordable electrification of automobiles (hybrids and EVs), buses, and ships. However, strategies to realize higher energy density and lower cost come at the expense of cell lifetime and safety. Extensive effort has been devoted to studying the effects of ALD coatings on cathode materials, with varying reports of the impact on full cell cycle life. The changes in surface chemistry of ALD-coated cathode particles and their specific effects on electrochemical performance have not been studied in detail. Unmodified particle surfaces contain active oxygen, LiOH, and Li2CO3 species. The chemistry of these species during delithiation and interaction with the electrolyte can introduce components of impedance that can limit the capacity and rate capability of the material. Moisture adsorption can occur over time which can interact with and generate more of these species, causing a further deterioration of capacity. We have shown that important functions of ALD are to “clean” the particle surfaces, decreasing the content of LiOH and moisture, and forming a barrier to water adsorption and further generation of these species. Thus an important mechanism of ALD enhancement of cathode materials in full cells is demonstrated. This understanding should be applied to past and future studies, and represents a powerful new strategy to mitigate the effects of moisture.

Contemporary applications of carbon black-filled polymer composites: An overview of essential aspects

This article appraises the contemporary reinforcement of carbon black in different polymer matrices. Essential features of polymer/carbon black composites are influenced by particle size, surface area, and surface chemistry of filler. Special emphasis is placed on recent research trends attained using polymer/carbon black composites. These materials have potential in fuel cells, sensors, detectors, supercapacitors, electromagnetic interference shielding, shape memory, dye-sensitized solar cells, and coatings. Various aspects, such as interfacial interaction, processing conditions, particle dispersion, and other physical properties, are highlighted for further exploration to discover hidden possibilities for these indispensable polymer composites.

Fingerprint resistant coatings for stainless steel substrates

Abstract In this paper, development of coatings with anti-finger print feature for stainless steel substrates is presented. Coatings with tailored surface roughness are demonstrated which provide these properties. Polyurethane coatings are produced by incorporation of matting agents with different particle size and surface chemistry. Depending on the amount of incorporated matting agents and their particle size, we were able to obtain anti-finger print coatings with the designed surface patterns. Chemical resistance tests of the coatings prove that they are chemically durable to be utilized in daily activities.