Manipulation Of Surface Chemistry Research Articles

Can MXene be the Effective Nanomaterial Family for the Membrane and Adsorption Technologies to Reach a Sustainable Green World?

Environmental pollution has intensified and accelerated due to a steady increase in the number of industries, and exploring methods to remove hazardous contaminants, which can be typically divided into inorganic and organic compounds, have become inevitable. Therefore, the development of efficacious technology for the separation processes is of paramount importance to ensure the environmental remediation. Membrane and adsorption technologies garnered attention, especially with the use of novel and high performing nanomaterials, which provide a target-specific solution. Specifically, widespread use of MXene nanomaterials in membrane and adsorption technologies has emerged due to their intriguing characteristics, combined with outstanding separation performance. In this review, we demonstrated the intrinsic properties of the MXene family for several separation applications, namely, gas separation, solvent dehydration, dye removal, separation of oil-in-water emulsions, heavy metal ion removal, removal of radionuclides, desalination, and other prominent separation applications. We highlighted the recent advancements used to tune separation potential of the MXene family such as the manipulation of surface chemistry, delamination or intercalation methods, and fabrication of composite or nanocomposite materials. Moreover, we focused on the aspects of stability, fouling, regenerability, and swelling, which deserve special attention when the MXene family is implemented in membrane and adsorption-based separation applications.

Surface Chemical Analysis of Hydroxyapatite Compared to Glass Ionomer and Amalgam Materials Used as Retrograde Filling Material in Dentistry

The aim of this study was to analyses the surface chemistry of different materials used as retrograde filling and compare it with bulk chemical analyses reported. Surface analysis carried out using an X—ray Photoelectron Spectrometer (XPS) built by VG Scientific. Samples of HAP, GIC and Amalgam materials used were prepared as Discs of 10 mm diameter. These transferred on to XPS aluminum stubs. XPS spectra were obtained from the wide scan spectrum of amalgam, the following elements are present: tin (23.2%); mercury (6.6%); carbon (19%) and oxygen (51.2%). The wide scan spectrum of GIC the elements present in the surface of the material are: oxygen (41.1%); aluminum (5%); silicon (4.6%); carbon (36.1%); calcium (11.3%); fluorine (2.1%) and sodium (0.T). The XPS spectra were obtained from the wide scan spectrum of Hydroxyapatite the elements present in the surface are: Oxygen (49-4%), Carbon (33-9%), calcium (8-6%), and Phosphorus (8-4%). In conclusion, the chemical XPS analyses of the materials used as retrograde filling, have shown them to vary considerably with respect to bulk chemical composition. Further surface analysis could include narrow scans, manipulation of surface chemistry, coupled with in vitro and in vivo tests and experiments to determine the importance of different surface components on biocompatibility.

Preparation of hexamethyl disilazane-surface functionalized nano-silica by controlling surface chemistry and its “agglomeration-collapse” behavior in solution polymerized styrene butadiene rubber/butadiene rubber composites

A series of nano-silicas with varying content of grafted hexamethyl disilazane (HMDS) modifier were prepared by liquid phase in-situ surface modification method in combination with granulation technology. The effect of the as-prepared nano-silica as fillers on the mechanical properties and abrasion resistance of solution polymerized styrene butadiene rubber (SSBR)/butadiene rubber (BR)-matrix composites were investigated. It was found that the content of the surface hydroxyl of the as-prepared organic-inorganic hybrids, HMDS-capped nano-silica, can be well tuned by adjusting the modifier dosage. The resultant HMDS-capped nano-silica have greatly improved dispersibility in rubber matrix as well as highly enhanced compatibility and interfacial interaction with the rubber matrix, which is favorable for improving the mechanical properties and abrasion resistance of the SSBR/BR-matrix composites. Particularly, the SSBR/BR-matrix composite filled with HMDS-capped nano-silica obtained at a modifier dosage of 20% (mass fraction) exhibits greatly improved mechanical properties and wet skid resistance(12.0%) as well as significantly reduced rolling-resistance(30.4%) and Akron abrasion(18.4%) as compared with the one filled with unmodified nano-silica. The present approach, with good access to surface chemistry manipulation of nano-silica, could help to promote the application of functionalized nano-silica in tire industry.

Engineering Surface Atomic Architecture of NiTe Nanocrystals Toward Efficient Electrochemical N2 Fixation

AbstractEfficient N2 fixation at ambient condition through electrochemical processes has been regarded as a promising alternative to traditional Haber–Bosch technology. Engineering surface atomic architecture of the catalysts to generate desirable active sites is important to facilitate electrochemical nitrogen reduction reaction (NRR) while suppressing the competitive hydrogen evolution reaction. Herein, nickel telluride nanocrystals with selectively exposed {001} and {010} facets are synthesized by a simple process, realizing the manipulation of surface chemistry at the atomic level. It is found that the catalysts expose the {001} facets coupled with desirable Ni sites, which possess high Faraday efficiency of 17.38 ± 0.36% and NH3 yield rate of 33.34 ± 0.70 μg h−1 mg−1 at ‐0.1 V vs RHE, outperforming other samples enclosed by {010} facets (8.56 ± 0.22%, 12.78 ± 0.43 μg h−1 mg−1). Both experimental results and computational simulations reveal that {001} facets, with selectively exposed Ni sites, guarantee the adsorption and activation of N2 and weaken the binding for *H species. Moreover, the enhanced reduction capacity and accelerated charge transfer kinetics also contribute the superior NRR performance of {001} facets. This work presents a novel strategy in designing nonprecious NRR electrocatalyst with exposed favorable active sites.

Engineering Surface Hydrophilicity via Polymer Chain-End Segregation in Coatings Formed by Photopolymerization

The manipulation of surface chemistry, and more precisely the hydrophilic/hydrophobic nature of an interfacial material, is essential for many applications in coatings, biomaterials, and microfluid...

Preparation of potassium intercalated carbons by in-situ activation and speciation for CO2 capture from flue gas

Nitrogen and/or sulfur doped carbons were extensively investigated as CO2 adsorbents, however their performance in CO2 capture from combustion flue gas, which is the largest stationary emission source, was less promising. Herein, potassium was used as a dopant for carbon, and a new series of materials, namely potassium intercalated carbons (PICs), were prepared sequentially by oxidation of mesoporous carbon, potassium ion exchange, and calcination. Based on results from FT-IR, XPS, TG-MS, etc., it was found the pre-loaded potassium interacted with the carbon matrix during calcination, enabled great flexibility in: (1) porosity adjustment by “in-situ activation”, and (2) surface chemistry manipulation by potassium intercalation. Taking together, the optimized sample (PIC-700) showed fast and stable CO2 uptake of 5.23 wt.% in flue gas conditions (40 °C, 1 bar, 15%CO2), which is among the highest for carbon-based adsorbents. Such promising performance is directly related to the enhanced CO2 affinity due to the presence of potassium dopants. Dynamic separation of CO2 from 15%CO2/85%N2 showed similar adsorption capacity, and no performance decay could be observed during temperature swing cycles, demonstrating the great potential for the PICs for practical CO2 capture applications.

Interplay of topologically interconnected mesoporous network and defects number density in improving electroactivity of graphene-single-walled carbon nanotube aerogels

Electroactivity of graphene-family nanomaterials and three-dimensional porous architectures is key for various applications at the grand challenges of “energy-water-sensing nexus.” It requires well-controlled morphology, manipulation of surface chemistry, interconnected topologic network, as well as electronic properties. Here, we demonstrate by taking advantage of hierarchical mesoporosity, optimized defects number density, nD (edges-plane and pore sites, oxygenated and nitrogenated functionalities), further invoked by synergistic coupling between one-dimensional single-walled carbon nanotube (SWCNT) as “nano” spacers and polymer linker with two-dimensional reduced graphene oxide derived three-dimensional scaffolds (known as aerogels) under hydrothermal conditions, and improved electrochemical (re)activity by enhancing the heterogeneous electron transfer rate (kET). We determined the correlation among nD, in-plane sp2C cluster, La and interdefect distance, LD (all via Raman spectroscopy), and kET (via scanning electrochemical microscopy) to establish “structure–property–functionality–electroactivity” relationships. The prominent Raman bands were also analyzed to determine the sp2-bonded C cluster size (La) for graphene- and nanotube-rich phases. The interplay of (1) rich surface redox chemistry due to carbonyl—C=O, carboxyl—COOH, pryridinic—N and pyrrolic—N functional groups, and geometric defects; (2) protruded edge plane and nanopores sites; (3) topological network; and (4) finite density of states with increased vacancy sites is emphasized and signifies the inherently activated electronic states in functionalized nanoporous composite carbon aerogels, for improved physicochemical processes (following graphene < N-graphene < graphene-SWCNT < N-graphene-SWCNT aerogels) relevant for electrocatalysis, thermo-electrochemical energy harvesting, desalination, and biosensing.

Front Cover: Modification of Carbon Fibre Surfaces by Sulfur‐Fluoride Exchange Click Chemistry (ChemPhysChem 23/2018)

The Front Cover shows a graphite surface representing carbon fibre and the sulfonyl fluoride groups attached the surface of the fiber in this work. The ability to tether molecules through such a stable and facile coupling unit is very useful in surface chemistry manipulation. More information can be found in the Communication by J. D. Randall et al. on page 3176 in Issue 23, 2018 (DOI: 10.1002/cphc.201800789).

Manipulating Reaction Rates of Metal-Oxide Heterogeneous Catalysts via Semiconductor Heterojunctions

Heterojunctions of metal oxide semiconductors enable the manipulation of surface chemistry for heterogeneous catalysts or sensors without introducing dopants and their attendant complications. If o...

Surface engineering of nanoparticles with macromolecules for epoxy curing: Development of super-reactive nitrogen-rich nanosilica through surface chemistry manipulation

Curing behavior of epoxy-based nanocomposites depends on dispersion state of nanofillers and their physical and chemical interactions with the curing moieties. In this work, a systematic approach was introduced for chemical functionalization of nanoparticles with macromolecules in order to enrich crosslinking potential of epoxy/amine systems, particularly at late stages of cure where the curing is diffusion-controlled. Super-reactive hyperbranched polyethylenimine (PEI)-attached nanosilica was materialized in this work to facilitate epoxy-amine curing. Starting from coupling [3-(2,3-epoxypropoxy) propyl] trimethoxysilane (EPPTMS) with hyperbranched PEI, a super-reactive macromolecule was obtained and subsequently grafted onto the nanosilica surface. Eventually, a thermally-stable highly-curable nanocomposite was attained by replacement of amine and imine groups of the PEI with imide and amide groups through the reaction with pyromellitic acid dianhydride. Fourier-transform infrared spectrophotometry, X-ray diffractometry, X-ray photoelectron spectroscopy and transmission electron microscopy approved successful grafting of polymer chains onto the nanosilica surface. Thermogravimetric analyses approved a relatively high grafting ratio of ca. 21%. Curing potential of the developed super-reactive nanoparticle was uncovered through nonisothermal differential scanning calorimetry signifying an enthalpy rise of ca. 120 J/g by addition of 2 wt.% to epoxy at 5 °C/min heating rate. Even at low concentration of 0.5 wt.%, the glass transition temperature of epoxy increased from 128 to 156 °C, demonstrating prolonged crosslinking.

Recent advances to accelerate re-endothelialization for vascular stents

Cardiovascular diseases are considered as one of the serious diseases that leads to the death of millions of people all over the world. Stent implantation has been approved as an easy and promising way to treat cardiovascular diseases. However, in-stent restenosis and thrombosis remain serious problems after stent implantation. It was demonstrated in a large body of previously published literature that endothelium impairment represents a major factor for restenosis. This discovery became the driving force for many studies trying to achieve an optimized methodology for accelerated re-endothelialization to prevent restenosis. Thus, in this review, we summarize the different methodologies opted to achieve re-endothelialization, such as, but not limited to, manipulation of surface chemistry and surface topography.

Carbon nanomaterials: Biologically active fullerene derivatives

Since their discovery, fullerenes, carbon nanotubes, and graphene attract significant attention of researches in various scientific fields including biomedicine. Nano-scale size and a possibility for diverse surface modifications allow carbon nanoallotropes to become an indispensable nanostructured material in nanotechnologies, including nanomedicine. Manipulation of surface chemistry has created diverse populations of water-soluble derivatives of fullerenes, which exhibit different behaviors. Both non-derivatized and derivatized fullerenes show various biological activities. Cellular processes that underline their toxicity are oxidative, genotoxic, and cytotoxic responses.The antioxidant/cytoprotective properties of fullerenes and derivatives have been considered in the prevention of organ oxidative damage and treatment. The same unique physiochemical properties of nanomaterials may also be associated with potential health hazards. Non-biodegradability and toxicity of carbon nanoparticles still remain a great concern in the area of biomedical application. In this review, we report on basic physical and chemical properties of carbon nano-clusters--fullerenes, nanotubes, and grapheme--their specificities, activities, and potential application in biological systems. Special emphasis is given to our most important results obtained in vitro and in vivo using polyhydroxylated fullerene derivative C₆₀(OH)₂₄.

Surface chemistry manipulation of gold nanorods preserves optical properties for bio-imaging applications

Due to their anisotropic shape, gold nanorods (GNRs) possess a number of advantages for biosystem use including, enhanced surface area and tunable optical properties within the near-infrared (NIR) region. However, cetyl trimethylammonium bromide-related cytotoxicity, overall poor cellular uptake following surface chemistry modifications, and loss of NIR optical properties due to material intracellular aggregation in combination remain as obstacles for nanobased biomedical GNR applications. In this article, we report that tannic acid-coated 11-mercaptoundecyl trimethylammonium bromide (MTAB) GNRs (MTAB-TA) show no significant decrease in either in vitro cell viability or stress activation after exposures to A549 human alveolar epithelial cells. In addition, MTAB-TA GNRs demonstrate a substantial level of cellular uptake while displaying a unique intracellular clustering pattern. This clustering pattern significantly reduces intracellular aggregation, preserving the GNRs NIR optical properties, vital for biomedical imaging applications. These results demonstrate how surface chemistry modifications enhance biocompatibility, allow for higher rate of internalization with low intracellular aggregation of MTAB-TA GNRs, and identify them as prime candidates for use in nanobased bio-imaging applications.

Assembly of Nanoscale Objects at the Liquid/Liquid Interface

The liquid–liquid interface provides a molecularly sharp, defect-free focal plane for the assembly of solid materials. In this article we discuss the various materials which have been successfully assembled at the liquid/liquid interface such as metallic nanoparticles, Janus particles, and carbon nanomaterials. Strategies to induce particle assembly include manipulation of surface chemistry, surface charge, and potential control. Liquid/liquid assembly can be exploited to synthesize materials in situ and template preformed structures. We go on to discuss the difficulties encountered when attempting to fully understand the structure of assemblies present at the liquid/liquid interface and the development of experimental techniques to elucidate information about the structure, stability, chemical composition, and reactivity of interfacial assemblies.

Thiol-Michael “click” chemistry: another efficient tool for head functionalization of giant surfactants

One of the challenges in the precise synthesis of giant surfactants lies in the homogenous functionalization of a head with bulky ligands. In this article, we report the use of thiol-Michael “click” chemistry as a facile, modular and robust approach to address this issue. A giant surfactant with acryloxyl-functionalized POSS (ACPOSS) head was conveniently constructed from commercially available acrylo POSS and polystyrene (PS). Functional thiols with different sizes, such as 2-mercaptoethanol, 1H,1H,2H,2H-perfluoro-1-decanethiol, 1-thio-β-D-glucose tetraacetate (sugar-SH), and 2-naphthalenethiol, were attached onto the head of the ACPOSS-PS conjugate by thiol-Michael and thiol–ene reactions. It was found that while both the methods offer a straightforward and highly efficient approach to prepare uniform and precise giant surfactants with small thiol ligands, only the former proceeds without apparent side reactions when large and bulky thiols, such as sugar-SH and 2-naphthalenethiol, are used. The former method also eliminates the need for UV irradiation or heat initiation. Therefore, the mild condition, high efficiency, and broad functional group tolerance of thiol-Michael chemistry should further expand the scope of POSS-based giant surfactants with unparalleled possibilities for head surface chemistry manipulation, which provides numerous opportunities for nanofabrication by the direct self-assembly of giant surfactants.

A comprehensive review of the application of chalcogenide nanoparticles in polymer solar cells.

In this review the use of solution-processed chalcogenide quantum dots (CdS, CdSe, PbS, etc.) in hybrid organic-inorganic solar cells is explored. Such devices are known as potential candidates for low-cost and efficient solar energy conversion, and compose the so-called third generation solar cells. The incorporation of oxides and metal nanoparticles has also been successfully achieved in this new class of photovoltaic devices; however, we choose to explore here chalcogenide quantum dots in light of their particularly attractive optical and electronic properties. We address herein a comprehensive review of the historical background and state-of-the-art comprising the incorporation of such nanoparticles in polymer matrices. Later strategies for surface chemistry manipulation, in situ synthesis of nanoparticles, use of continuous 3D nanoparticles network (aerogels) and ternary systems are also reviewed.

ChemInform Abstract: Synthesis and Properties of Colloidal Heteronanocrystals

AbstractReview: 283 refs.

Synthesis and properties of colloidal heteronanocrystals

Colloidal heteronanocrystals (HNCs) can be regarded as solution-grown inorganic-organic hybrid nanomaterials, since they consist of inorganic nanoparticles that are coated with a layer of organic ligand molecules. The hybrid nature of these nanostructures provides great flexibility in engineering their physical and chemical properties. The inorganic particles are heterostructured, i.e. they comprise two (or more) different materials joined together, what gives them remarkable and unique properties that can be controlled by the composition, size and shape of each component of the HNC. The interaction between the inorganic component and the organic ligand molecules allows the size and shape of the HNCs to be controlled and gives rise to novel properties. Moreover, the organic surfactant layer opens up the possibility of surface chemistry manipulation, making it possible to tailor a number of properties. These features have turned colloidal HNCs into promising materials for a number of applications, spurring a growing interest on the investigation of their preparation and properties. This critical review provides an overview of recent developments in this rapidly expanding field, with emphasis on semiconductor HNCs (e.g., quantum dots and quantum rods). In addition to defining the state of the art and highlighting the key issues in the field, this review addresses the fundamental physical and chemical principles needed to understand the properties and preparation of colloidal HNCs (283 references).

The Biological Mechanisms and Physicochemical Characteristics Responsible for Driving Fullerene Toxicity

This review provides a comprehensive critical review of the available literature purporting to assess the toxicity of carbon fullerenes. This is required as prior to the widespread utilization and production of fullerenes, it is necessary to consider the implications of exposure for human health. Traditionally, fullerenes are formed from 60 carbon atoms, arranged in a spherical cage-like structure. However, manipulation of surface chemistry and molecular makeup has created a diverse population of fullerenes, which exhibit drastically different behaviors. The cellular processes that underlie observed fullerene toxicity will be discussed and include oxidative, genotoxic, and cytotoxic responses. The antioxidant/cytoprotective properties of fullerenes (and the attributes responsible for driving these phenomena) have been considered and encourage their utilization within the treatment of oxidant-mediated disease. A number of studies have focused on improving the water solubility of fullerenes in order to enable their exploitation within biological systems. Manipulating fullerene water solubility has included the use of surface modifications, solvents, extended stirring, and mechanical processes. However, the ability of these processes to also impact on fullerene toxicity requires assessment, especially when considering the use of solvents, which particularly appear to enhance fullerene toxicity. A number of the discussed investigations were not conducted to reveal if fullerene behavior was due to their nanoparticle dimensions but instead addressed the biocompatibility and toxicity of fullerenes. The hazards to human health, associated with fullerene exposure, are uncertain at this time, and further investigations are required to decipher such effects before an effective risk assessment can be conducted.