Influence Of Surface Chemistry Research Articles

Influence of chemistry and topography on the wettability of copper

To understand the complex interplay of topography and surface chemistry in wetting, fundamental studies investigating both parameters are needed. Due to the sensitivity of wetting to miniscule changes in one of the parameters it is imperative to precisely control the experimental approach. A profound understanding of their influence on wetting facilitates a tailored design of surfaces with unique functionality.We present a multi-step study: The influence of surface chemistry is analyzed by determining the adsorption of volatile carbonous species (A) and by sputter deposition of metallic copper and copper oxides on flat copper substrates (B). A precise surface topography is created by laser processing. Isotropic topography is created by ps laser processing (C), and hierarchical anisotropic line patterns are produced by direct laser interference patterning (DLIP) with different pulse durations (D).Our results reveal that the long-term wetting response of polished copper surfaces stabilizes with time despite ongoing accumulation of hydrocarbons and is dominated by this adsorption layer over the oxide state of the substrate (Cu, CuO, Cu2O). The surfaces’ wetting response can be precisely tuned by tailoring the topography via laser processing. The sub-pattern morphology of primary line-like patterns showed great impact on the static contact angle, wetting anisotropy, and water adhesion. An increased roughness inside the pattern valleys combined with a minor roughness on pattern peaks favors air-inclusions, isotropic hydrophobicity, and low water adhesion. Increasing depth of the primary topography can also induce air-inclusions despite increasing peak roughness while time dependent wetting transitions were observed.

Surface energy considerations for offset printing of coated paper and paperboard

Offset printing of coated paper involves the complex interactions of ink with a surface that is characterized by three major properties: roughness, porosity, and related pore network structure and surface chemistry (related to surface free energy [SFE]). The effects of porosity and roughness are relatively well understood and are documented in the literature, whereas the influence of surface chemistry is much less studied and therefore the focus of this paper. The key results shown include: i) Coating porosity has a negligible effect on SFE determination by contact angle using two fluids. ii) The chemistry of the latex polymer in the coating formulation dominates the influence on SFE compared to pigment, with any surface energy differences present in the pigment being almost completely masked by latex. iii) Wetting agent and corona treatment can impact water absorption rate and surface spreading of water, resulting in small differences in printability. Increasing the concentration of the surfactant on a coated surface indicates switching orientation of the surfactant molecules, giving a “step wise” printing result. When looking to improve offset printability by selection of different pigments, the variation in SFE is less important than variation in either surface roughness or porosity.

Insights into the effect of oxygen functional groups on the heterogeneous electron transfer at activated carbons from scanning electrochemical microscopy

The influence of surface chemistry on heterogeneous electron transfer at activated carbon (AC) electrodes was studied using scanning electrochemical microscopy (SECM) and conventional electrochemical measurements, which allow for measuring respectively the local and the overall electrode electron transfer rate constants. Using a thermal treatment in air and under argon, commercial activated carbons were either oxidized or defunctionalized. Both treatments lead to a slight decrease of the specific surface area of the material, without altering its pore size distribution and morphology. The nanogap voltammetry and approach curves obtained by SECM were used to characterize the rate constants at the interface between an aqueous solution of ferrocenemethanol (FcMeOH) and the AC electrodes. The heterogeneous electron transfer (HET) rate constant for the untreated AC was 3.4 10−2 ± 0.2 cm s−1 and was increased by about 2.5 and 1.5 times, after oxidizing and defunctionalizing the surface, respectively. SECM results showed that the heat treatment increases the conductivity of AC, and the oxidation of the surface increases the wettability and accessibility of the pores, which are assumed to promote the electron transfer. The local heterogeneous electron transfer rate constant values obtained by SECM are higher, by an order of magnitude, than the global ones obtained from conventional electrochemical macroelectrode measurements. The local information obtained by SECM is valuable for understanding the nanoscale interfacial mechanisms in porous carbon electrodes as a better understanding of the charge storage mechanism is key to improve their electrochemical performances.

Different Roles of Surface Chemistry and Roughness of Laser-Induced Graphene: Implications for Tunable Wettability.

The control of surface wettability is a technological key aspect and usually poses considerable challenges connected to high cost, nanostructure, and durability, especially when aiming at surface patterning with high and extreme wettability contrast. This work shows a simple and scalable approach by using laser-induced graphene (LIG) and a locally inert atmosphere to continuously tune the wettability of a polyimide/LIG surface from hydrophilic to superhydrophobic (Φ ∼ 160°). This is related to the reduced amount of oxygen on the LIG surface, influenced by the local atmosphere. Furthermore, the influence of the roughness pattern of LIG on the wettability is investigated. Both approaches are combined, and the influence of surface chemistry and roughness is discussed. Measurements of the roll-off angle show that LIG scribed in an inert atmosphere with a low roughness has the highest droplet mobility with a roll-off angle of ΦRO = (1.7 ± 0.3)°. The superhydrophobic properties of the samples were maintained for over a year and showed no degradation after multiple uses. Applications of surfaces with extreme wettability contrast in millifluidics and fog basking are demonstrated. Overall, the proposed processing allows for the continuous tuning and patterning of the surface properties of LIG in a very accessible fashion useful for "lab-on-chip" applications.

Influence of Surface Chemistry of Fiber and Lignocellulosic Materials on Adhesion Properties with Polybutylene Succinate at Nanoscale.

The production of bio-based composites with enhanced characteristics constitutes a strategic action to minimize the use of fossil fuel resources. The mechanical performances of these materials are related to the specific properties of their components, as well as to the quality of the interface between the matrix and the fibers. In a previous research study, it was shown that the polarity of the matrix played a key role in the mechanisms of fiber breakage during processing, as well as on the final properties of the composite. However, some key questions remained unanswered, and new investigations were necessary to improve the knowledge of the interactions between a lignocellulosic material and a polar matrix. In this work, for the first time, atomic force microscopy based on force spectroscopy measurements was carried out using functionalized tips to characterize the intermolecular interactions at the single molecule level, taking place between poly(butylene succinate) and four different plant fibers. The efficiency of the tip functionalization was checked out by scanning electron microscopy and energy-dispersive X-ray spectroscopy, whereas the fibers chemistry was characterized by Fourier-transform infrared spectroscopy. Larger interactions at the nanoscale level were found between the matrix and hypolignified fibers compared to lignified ones, as in control experiments on single lignocellulosic polymer films. These results could significantly aid in the design of the most appropriate composite composition depending on its final use.

Influence of surface chemistry and channel shapes on the lithium-ion separation in metal-organic-framework-nanochannel membranes

Metal-organic-framework-based channel (MOFC) membranes have great potential in ion separation due to their high flexibility than polycrystalline MOF membranes. Although a few single-MOFC membranes with high ion selectivity and permeability have been reported, the scale-up of MOFC membranes from single-channel membranes to multichannel membranes remains a challenge as defects with the system are escalated, limiting their practical application. Minimizing defects in multichannel MOFC membranes is the key to solving this scale-up challenge. Herein, the surface chemistry of polyethylene terephthalate (PET) nanochannel substrate was firstly tuned by a chemical modification to enhance the binding between the PET nanochannel walls and UiO-66-(COOH)2 MOF crystals. Further investigation of the influences of PET nanochannels' size, shape, and channel density on the selectivity revealed that the cylindrical and ethylenediamine (EDA)-functionalized single PET-UiO-66-(COOH)2 MOFC membrane exhibited an ultrahigh Li+/Mg2+ selectivity of 3077-fold over those of previous single-MOFC works. Furthermore, cylindrical, EDA-functionalized, multichannel UiO-66-(COOH)2 MOFC membranes with a channel density of 106/cm2 have been fabricated to achieve 50-fold Li+/Mg2+ selectivity and a vast enhancement of Li + conductance for 6 orders of magnitude. As the first example of scaling up the MOFC membrane, this work provides a fundamental basis and experimental techniques for MOF membrane synthesis and lithium-ion extractions.

Unique Porous Structures Supported by Anodic Treatments in Liquid Ammonia (-50°C, Patm)

Since the first anodic porosification of semiconductors in the 1950s, numerous studies have reported a wide range of porous structures. The conditions used during the growth of pores can explained the shapes obtained but the formation mechanism and especially the influence of surface chemistry during porosification still raise many questions.It is in such context that the contribution of liquid ammonia (-55°C) is crucial. Indeed, this remarkable non-aqueous solvent allows, on the one hand, to obtain novel porous structures on n-InP and, on the other hand, it allows for the first time a specific and original interfacial chemistry, governed by the chemistry of nitrogen.In fact, in liquid ammonia, the dissolution of III-V semiconductors (GaAs, InP) is systematically done after a surface passivation step. This passivation step is particularly stable on InP and revealed the formation of a phosphazene type film (monolayer) resulting from the concomitant oxidation of the solvent and the semiconductor. The "multi-material" approach is a key factor, as it underlines the determinant role of the surface chemistry. In fact, at higher current densities, the porous structures of n-InP and n-GaAs show contrasting structures, which give an original behaviour compared to the aqueous medium. In order to determine the efficiency of the dissolution mechanism (at lower and higher current density), the quantity of indium (or gallium) salt will be quantified by Inductively coupled plasma optical emission spectroscopy analysis after ammonia evaporation.Moreover, the remarkable reproducibility of the anodic behaviour allowed physico-chemical characterisations of the porous surface, supported by scanning electron microscopy and the variation of the interfacial potential, photoluminescence and X-ray photoelectron spectroscopy.More specifically on n-InP, where an original structure was revealed, these analyses, during the early stages of porosification, led to the identification of a porosification mechanism in this solvent. Furthermore, at higher current densities, an amorphous film becomes thicker on the surface of the porous structure. Further porosification requires the permeability of this amorphous structure which would most probably result from the polymerisation of phosphazene since the presence of nitrogen could be clearly identified on the pore walls by Auger spectroscopy.

Unique Porous Structures Supported by Anodic Treatments in Liquid Ammonia (-50°C, Patm)

Since the first anodic porosification of semiconductors in the 1950s, numerous studies have reported a wide range of porous structures. The conditions used during the growth of pores can explain the shapes obtained but the growth mechanism and especially the influence of surface chemistry during the porosification still raise many questions. It is in this context that the contribution of liquid ammonia (-55°C, Patm) is significant. Indeed, this remarkable non-aqueous solvent allows, on the one hand, to obtain novel porous structures on III-Vsc, and on the other hand, it allows for the first time a specific and original interfacial chemistry, governed by the chemistry of nitrogen.

Influence of Surface Chemistry on the Surfactant Organization and Interfacial Structure of Mesoporous Silica and Organosilica

Mesoporous silica (SiO2) and periodic mesoporous organosilica (PMO) with divinylbenzene (DVB)- and divinylaniline (DVA)-bridge groups are studied by solid-state NMR and molecular dynamics simulations to examine the influence of the surface chemistry on the interfacial interactions and the assembly structures of the surfactants. The NMR signals of the surfactants inside the mesopores appear at different chemical shift values depending on the organic bridging groups. Two-dimensional NMR spectroscopy shows that the surfactants assemble as micellar structures, where the polar head groups directly interact with the pore walls, and the interaction strength of the surfactants with pore wall is in the order of SiO2 >DVA-PMO > DVB-PMO. To elucidate the functional dependence of the interfacial structure of SiO2 and PMOs, the radial distribution function is calculated from molecular dynamics simulations, which provides individual atomic correlations quantitatively. For SiO2, the surfactant head is preferentially adsorbed to the inorganic layer with extended aliphatic tail group packing, whereas the adsorption of the surfactant head group to the pore wall is weaker for PMOs. We find that the hydrophobic interaction between DVB and the surfactant tail, which is stronger than that in the case of polar DVA, weakens the interaction between the surfactant head and organic layer for DVB-PMO more than for DVA-PMO. From the conformational analysis, we directly observe a more abundant gauche defect of the surfactant in DVA-PMO than in DVB-PMO. The upfield NMR shift in DVB-PMO is revealed by more planar aromatic ring orientation, which is caused by the steric effect between the organic groups. Our study suggests that the hydrophobicity and bulkiness of the organic bridge can be exploited in the design of PMOs for molecular machines, absorbents, and enzyme immobilization materials.

The influence of surface chemistry upon the textural, thermal and sorption properties of apple-pectin adsorbent materials

The influence of surface chemistry upon the textural, thermal and sorption properties of apple-pectin adsorbent materials

(Invited) Quantitatively Designing Porous Copper Current Collectors for Lithium Metal Anodes

Lithium metal has been an attractive candidate as a next-generation anode material. Despite its popularity, stability issues of lithium in the liquid electrolyte and the formation of lithium whiskers have kept it from practical use. Three-dimensional (3D) current collectors have been proposed as an effective method to mitigate whiskers growth. Although extensive research has been done, the effects of three key parameters of the 3D current collectors, namely the surface area, the tortuosity factor, and the surface chemistry, on the performance of lithium metal batteries remain elusive. Herein, we quantitatively studied the role of these three parameters by synthesizing four types of porous copper networks with different sizes of well-structured micro-channels. X-ray microscale computed tomography (micro-CT) allowed us to assess the surface area, the pore size and the tortuosity factor of the porous copper materials. A metallic Zn coating was also applied to study the influence of surface chemistry on the performance of the 3D current collectors. The effects of these parameters on the performance were studied in detail through Scanning Electron Microscopy (SEM) and Titration Gas Chromatography (TGC). Stochastic simulations further allowed us to interpret the role of the tortuosity factor in lithiation. The optimal range of the key parameters is thereby found for the porous coppers and their performance is predicted. Using these parameters to inform the design of porous copper anodes for Li deposition, Coulombic efficiencies (CE) of up to 99.63% are achieved, thus paving the way for the design of effective 3D current collector systems.

The Effect of Sibunit Carbon Surface Modification with Diazonium Tosylate Salts of Pd and Pd-Au Catalysts on Furfural Hydrogenation.

Herein, we investigated the effect of the support modification (Sibunit carbon) with diazonium salts of Pd and Pd-Au catalysts on furfural hydrogenation under 5 bars of H2 and 50 °C. To this end, the surface of Sibunit (Cp) was modified with butyl (Cp-Butyl), carboxyl (Cp-COOH) and amino groups (Cp-NH2) using corresponding diazonium salts. The catalysts were synthesized by the sol immobilization method. The catalysts as well as the corresponding supports were characterized by Fourier transform infrared spectroscopy, N2 adsorption-desorption, inductively coupled plasma atomic emission spectroscopy, high resolution transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Hammet indicator method and X-ray photoelectron spectroscopy. The analysis of the results allowed us to determine the crucial influence of surface chemistry on the catalytic behavior of the studied catalysts, especially regarding selectivity. At the same time, the structural, textural, electronic and acid–base properties of the catalysts were practically unaffected. Thus, it can be assumed that the modification of Sibunit with various functional groups leads to changes in the hydrophobic/hydrophilic and/or electrostatic properties of the surface, which influenced the selectivity of the process.

Electrical sensing of volatile organic compounds in exhaled breath for disease diagnosis

In recent years, electrical sensors toward breath volatolomics have attracted increasing interest owing to their wide feasibility in noninvasive disease diagnostics. In this article, the working principles of active nanomaterials (e.g. metal oxides, polymers, and nanocarbon) toward volatile organic compounds are presented, with a special focus on the influence of surface chemistry and structural feature of these nanomaterials on the sensing performance. The latest and representative achievements on the direct analysis of three typical exhaled volatile organic compounds, including acetone, ammonia, and hydrogen sulfide, that are recognized as important disease biomarkers, are highlighted, indicating the capability of the electrical sensors in enabling noninvasive diagnosis and real-time monitoring. The opportunities and challenges in this field are provided in the end, with an emphasis on the background interference and data recognition which are key factors in developing prospective electrical sensors toward volatolomics analysis.

Comparative study of mechanical strengths of cement pastes incorporating carbon nanomaterials with distinct surface chemistry and morphology

This work investigated the use of two-dimensional graphene oxide (GO), one-dimensional oxidized carbon nanotube (OCNT) and graphene oxide nanoribbon (GONR), with a C/O ratio of 0.77, 2.79, 33.5, respectively, to reveal how the surface chemistry and dimensionality of carbon nanomaterials (CNMs) affect the mechanical strengths of cement pastes. The prepared GONR features the high oxidation degree similar to GO and high aspect ratio similar to OCNT, thus exhibiting both the characteristics of GO and OCNT in enhancing the mechanical strengths of cement pastes. With 0.01 wt% GONR admixed, the flexural and compressive strengths of cement pastes at 28 days were improved by 35.9% and 16.7%, respectively. Among the three CNMs, those with a higher oxidation degree promoted the formation of hydration products. Findings from this exploratory study shed light on the influence of surface chemistry and morphology of CNMs on cementitious composites.

Influence of surface chemistry and morphology of nanoparticles on protein corona formation.

Nanomaterials offer promising solutions as drug delivery systems and imaging agents in response to the demand for better therapeutics and diagnostics. However, the limited understanding of the interaction between nanoparticles and biological entities is currently hampering the development of new systems and their applications in clinical settings. Proteins and lipids in biological fluids are known to complex with nanoparticles to form a “biomolecular corona”. This has been shown to affect particles' morphology and behavior in biological systems and their interactions with cells. Hence, understanding how nanomaterials' physicochemical properties affect the formation and composition of this biocorona is a crucial step. This work evaluates existing literature on how morphology (size and shape), and surface chemistry (charge and hydrophobicity) of nanoparticles influence the formation of protein corona. The latest evidence suggest that although surface charge promotes the interaction with proteins and lipids, surface chemistry plays a leading role in determining the affinity of the nanoparticle for biomolecules and, ultimately, the composition of the corona. More recently the study of additional nanoparticles' properties like shape and surface chirality have demonstrated a significant effect on protein corona architecture, providing new tools to tailor biomolecular corona formation.This article is categorized under:Therapeutic Approaches and Drug Discovery > Emerging TechnologiesToxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials

The Influence of Surface Chemistry on Critical Current Density for Garnet Electrolyte

AbstractGarnet‐based solid state lithium batteries have attracted a lot of attention due to their potential advantages in safety and energy density. However, the high electrode–electrolyte interfacial resistance and low critical current density (CCD) related with lithium dendrite penetration have seriously hindered their further development and practical application. Here, for garnet‐type solid electrolyte, the surface Li2CO3, interlayer species, lithium wettability, interfacial impedance, and CCD are systematically investigated. It turns out that Li2CO3‐free garnet electrolyte is intrinsically lithiophilic, and the interfacial impedance is mainly affected by the amount of surface Li2CO3. In addition, the CCD values are manipulated by the interfacial impedance rather than the apparent Li wettability. This study provides a comprehensive understanding about the interrelationships among surface chemistry, lithium wettability, interfacial impedance, and critical current density for garnet‐type solid electrolytes.

Topography versus chemistry – How can we control surface wetting?

HypothesisWetting characterization and the production of engineered surfaces showing distinct contact angles or spreading behavior is of major importance for many industrial and scientific applications. As chemical composition plays a major role in the wetting behavior of flat samples, wettability, capillary forces and resulting droplet spreading on anisotropic surface patterns are expected to be highly dependent on surface chemistry as well. ExperimentsTo gain understanding of the fundamental principles of the interplay between surface topography and surface chemistry regarding water wettability, anisotropic line patterns were produced on steel samples in a direct laser writing process. Homogeneous surface coatings allowed for a chemical masking of the laser patterns and therewith the identification of the influence of surface chemistry on static contact angles and wetting anisotropy. FindingsWhile a carbon coating leads to pronounced wettability and spreading along the topographic anisotropy, an inert gold–palladium coating can fully suppress anisotropic droplet spreading. Model calculations show that an amorphous carbon coating leads to Wenzel wetting while the gold–palladium coating causes air inclusions between the water and the surface in the Cassie-Baxter wetting state. Only in combination with the right chemical composition of the surface, directional patterns show their potential of anisotropic wetting behavior.

Faster Nucleation of Ice at the Three-Phase Contact Line: Influence of Interfacial Chemistry.

Controlling the nucleation of ice is important in many areas including atmospheric sciences, cryopreservation, food science, and infrastructure protection. Presently, we conduct controlled experiments and analysis to uncover the influence of surface chemistry at the three-phase line on ice nucleation. We show that ice nucleation is faster upon replacing the air at the water-air interface with oils like silicone oil and almond oil. We show via statistically meaningful and carefully designed experiments that ice nucleation occurs at a higher temperature at an aluminum-water-silicone oil (or almond oil) interface as compared to an aluminum-water-air interface. We show that the location of ice nucleation can be controlled (in situations with multiple locations for ice nucleation) by controlling the interfacial chemistry at the three-phase line. We develop a model (which utilizes classical nucleation theory) to study the combined influence of two interfaces on a seed crystal of ice originating at the three-phase contact line. This model can evaluate the thermodynamic competition between nucleation at the three -phase line and heterogeneous nucleation at an interface. The model shows that three-phase contact lines usually result in a higher driving force than heterogeneous nucleation, which speeds up nucleation kinetics. Overall, our experiments and modeling uncover several useful insights into the influence of three-phase lines on nucleation during contact freezing.

Quantitatively Designing Porous Copper Current Collectors for Lithium Metal Anodes

Lithium metal has been an attractive candidate as a next-generation anode material. Despite its popularity, stability issues of lithium in the liquid electrolyte and the formation of lithium whiskers have kept it from practical use. Three-dimensional (3D) current collectors have been proposed as an effective method to mitigate whiskers growth. Although extensive research has been done, the effects of three key parameters of the 3D current collectors, namely the surface area, the tortuosity factor, and the surface chemistry, on the performance of lithium metal batteries remain elusive. Herein, we quantitatively studied the role of these three parameters by synthesizing four types of porous copper networks with different sizes of well-structured micro-channels. X-ray microscale computed tomography (micro-CT) allowed us to assess the surface area, the pore size and the tortuosity factor of the porous copper materials. A metallic Zn coating was also applied to study the influence of surface chemistry on the performance of the 3D current collectors. The effects of these parameters on the performance were studied in detail through Scanning Electron Microscopy (SEM) and Titration Gas Chromatography (TGC). Stochastic simulations further allowed us to interpret the role of the tortuosity factor in lithiation. The optimal range of the key parameters is thereby found for the porous coppers and their performance is predicted. Using these parameters to inform the design of porous copper anodes for Li deposition, Coulombic efficiencies (CE) of up to 99.63% are achieved, thus paving the way for the design of effective 3D current collector systems.

Ligand Exchange and Impurity Doping in 2D CdSe Nanoplatelet Thin Films and Their Applications

AbstractThe effects of halide‐ligand exchange and Cu and Ag doping are studied on structural, optical, and electrical properties of four monolayer CdSe nanoplatelet (NPL) and NPL thin films. Combinational study shows that NH4Cl‐treatment on CdSe NPL and NPL thin films show tetragonal lattice distortion of NPL, side‐to‐side attachment between NPLs, bathochromic shift in absorption spectra, and complete quenching of band‐edge and dopant‐induced emissions. First‐principle calculations reveal that Cl creates states below valence band maximum while Ag and Cu dopants create acceptor‐like states, explaining the change of their optical property. Field‐effect transistors are fabricated to investigate the effect of doping and reduced interplatelet distance on electrical properties of CdSe NPL thin films, demonstrating Cu and Ag dopants mitigate n‐type character of CdSe NPL thin films. Temperature‐dependent electrical characterization is conducted to further understand charge transport behavior depending on the existence of dopants. This work provides scientific information on the influence of surface chemistry and impurity doping on quantum confined semiconductors and new directions for the design of high‐performance nanomaterial‐based electronic and optoelectronic devices.