Bulk Modification Research Articles

In‐Volume Laser Direct Writing of Silicon—Challenges and Opportunities

AbstractLaser direct writing is a widely employed technique for 3D, contactless, and fast functionalization of dielectrics. Its success mainly originates from the utilization of ultrashort laser pulses, offering an incomparable degree of control on the produced material modifications. However, challenges remain for devising an equivalent technique in crystalline silicon which is the backbone material of the semiconductor industry. The physical mechanisms inhibiting sufficient energy deposition inside silicon with femtosecond laser pulses are reviewed in this article as well as the strategies established so far for bypassing these limitations. These solutions consisting of employing longer pulses (in the picosecond and nanosecond regime), femtosecond‐pulse trains, and surface‐seeded bulk modifications have allowed addressing numerous applications.

A new nanoparticle-reinforced silicone rubber composite integrating high strength and strong adhesion

A bulk modification method is developed in this paper to achieve a new nanoparticle-reinforced silicone rubber composite with high strength and strong adhesion. Different from existing modification methods, an adhesion promoter is added in order to improve the adhesive property in addition to the surface modified silica nanoparticle. Furthermore, the adhesion promoter also exhibits an excellent compatibility with the silicone rubber. The tensile strength and shear adhesive strength of the new composite can reach up to 10.4 MPa and 90 kPa, respectively, both of which are much higher than their counterparts in the popular silicone rubber product Sylgard184. Moreover, the strong adhesion performance of the composite exhibits a good stability in either several-hour use or many attachment/detachment cycles. The present composite shows apparent advantages over existing silicone rubber products in not only the direct use as an adhesive material, but also potential applications for manufacturing advanced adhesive devices such as wearable electronics.

Surface and Bulk Modifications of Fibrous Erionite in Mimicked Gamble’s Solution at Acidic pH

This study aimed at investigating both the surface and bulk modifications occurring on fibrous erionite during leaching in a mimicked Gamble’s solution (MGS) at pH of 4.5 and T = 37 °C, up to one month of incubation. Samples were characterized by a multi-analytical approach: field-emission scanning electron microscopy (FE-SEM) was employed to investigate the morphological changes of both pristine and reacted fibres, inductively coupled plasma optical emission spectrometry (ICP-OES) was used to measure the concentration of the released cations; X-ray photoelectron spectroscopy (XPS) was exploited for highlighting possible modifications of surface chemistry; X-ray powder diffraction (XRPD) and high-resolution transmission electron microscopy (HR-TEM) were applied aiming to get information on the structural state of the fibres following the incubation. ICP results integrated with those obtained by both bulk- and surface-chemical characterization highlighted that erionite binds Na especially in the first 24 h of sample incubation in the MGS, following ion exchange with the extra framework cations, in particular Ca. Moreover, our new results show that the Na binding process caused structural modifications with the migration of Na toward the Ca2 site and redistribution of the cations within the erionite cage. TEM investigation pointed out that the interaction between erionite and MGS results in the formation of a new surface amorphous layer with an irregular lobate pattern on an earlier surface weathered layer. However, the silicate framework is not weakened by incubation in the MGS at acidic pH. In addition, on the basis of the Si release normalized to the mineral surface area, fibrous erionite resulted significantly more biodurable than amphibole asbestos. Notably, considering the primary role played by biodurability in inducing pathogenicity, this result certainly supports in vivo observations showing that erionite is much more tumorigenic than asbestos. Moreover, the ions released by erionite when immersed in MGS may trigger biological effects, such as those on lipid packing and membrane permeability. On this basis, we expect a regulatory definition that would provide protection from this carcinogenic fibre.

Graphitic Carbon Nitride as a New Sustainable Photocatalyst for Textile Functionalization.

As a promising organic semiconducting material, polymeric graphitic carbon nitride (g-C3N4) has attracted much attention due to its excellent optical and photoelectrochemical properties, thermal stability, chemical inertness, nontoxicity, abundance, and low cost. Its advantageous visible light-induced photocatalytic activity has already been beneficially used in the fields of environmental remediation, biological applications, healthcare, energy conversion and storage, and fuel production. Despite the recognized potential of g-C3N4, there is still a knowledge gap in the application of g-C3N4 in the field of textiles, with no published reviews on the g-C3N4-functionalization of textile materials. Therefore, this review article aims to provide a critical overview of recent advances in the surface and bulk modification of textile fibres by g-C3N4 and its composites to tailor photocatalytic self-cleaning, antibacterial, and flame retardant properties as well as to create a textile catalytic platform for water disinfection, the removal of various organic pollutants from water, and selective organic transformations. This paper highlights the possibilities of producing g-C3N4-functionalized textile substrates and suggests some future prospects for this research area.

Surface and bulk modifications of amphibole asbestos in mimicked gamble's solution at acidic PH

This study aimed at investigating the surface modifications occurring on amphibole asbestos (crocidolite and tremolite) during leaching in a mimicked Gamble’s solution at pH of 4.5 and T = 37 °C, from 1 h up to 720 h. Results showed that the fibre dissolution starts with the release of cations prevalently allocated at the various M- and (eventually) A-sites of the amphibole structure (incongruent dissolution). The amount of released silicon, normalized to fibre surface area, highlighted a leaching faster for the crocidolite sample, about twenty times higher than that of tremolite. Besides, the fast alteration of crocidolite promotes the occurrence of Fe centres in proximity of the fibre surface, or possibly even exposed, particularly in the form of Fe(II), of which the bulk is enriched with respect to the oxidized surface. Conversely, for tremolite fibres the very slow fibre dissolution prevents the underlying cations of the bulk to be exposed on the mineral surface, and the iron oxidation, faster than the leaching process, significantly depletes the surface Fe(II) centres initially present. Results of this work may contribute to unravel possible correlations between surface properties of amphibole asbestos and its long-term toxicity.

A simple method to create hydrophobic mortar using bacteria grown in liquid cultures

The ingress of water-soluble aggressive species is a major cause to the reduced service life of concrete structures. Bulk modification by adding hydrophobic agents in the cementitious materials is commonly applied to reduce water penetration into the concrete matrix. However, conventional hydrophobic modifications of concrete are associated with several unresolved major drawbacks such as high cost and toxicity. Here, we investigate the impact of safe and easy-to-culture bacteria on the hydrophobic properties of concrete. We demonstrate that hydrophobic concrete can be conveniently created by using the liquid culture of bacteria without the need of growing biofilms as suggested by previous research, even with a strain that does not present innate hydrophobicity. These key findings greatly improve the feasibility for the large-scale application of water resistance cementitious materials. Scanning electron microscopy and X-ray diffraction analyses indicated higher levels of micro-calcite formations with the increased addition of bacteria. These micro-calcite structures account for the dramatic increase in surface roughness which leads to elevated hydrophobic properties of the hybrid concrete. This phenomenon is reminiscent of the “lotus-leaf effect”, with ultrahydrophobicity arising from the nano- and microscopic topologies of surfaces. Bacteria-modified cement presents distinct heat-flow profiles during hydration consistent with the increased calcite formation. Taken together, this research gives unprecedented mechanistic insight into the design of microbial-modified concrete with hydrophobic properties particularly useful in floating and offshore structures. Given the large repertoire of bacteria still to be used, our work sets the stage for the future design of microbial-based hydrophobic concrete that can be tailored with additional functions such as self-healing and odor removal.

Editorial: Inorganic Chemistry Editor’s Pick 2021

strong community by recognizing highly deserving authors. The selected manuscripts highlight the broad diversity of research performed across the section, including the synthesis and general characterization (e.g., structural, magnetic, optical) of coordination polymers and metal-organic frameworks (MOFs) and its application for sensing, nanoplates for supercapacitors, nanophosphors for upconversion and the dielectric properties of carbon nanotubes, for instance. The review manuscripts encompass the biomolecular modification of MOFs, bulk and nano metal oxysulfides, rhenium complexes as probes for prokaryotic and fungal cells, and atomistic simulations of rareearth orthophosphates.All research presented here illustrates strong advances in experiments, theory, and in silico with applications to compelling problems aiming to put a spotlight on the main areas of interest for the section.

Direct ink writing of dehydrofluorinated Poly(Vinylidene Difluoride) for microfiltration membrane fabrication

Here, a hybrid process for the fabrication of dehydrofluorinated PVDF (dPVDF) microfiltration (MF) membranes is presented. dPVDF was fabricated through the bulk modification of PVDF using ethylenediamine. To produce inks for direct ink writing (DIW), the dPVDF was dissolved in N,N-dimethyacetamide along with a pore-forming agent, poly(vinyl pyrrolidone) (PVP) (5–30 wt%, relative to dPVDF concentration). Membranes were produced by direct ink writing of the inks into continuous films - followed by non-solvent induced phase separation (NIPS). Attenuated total reflectance – Fourier transform infrared (ATR-FTIR) and Raman spectroscopies confirmed alkene moieties within the dPVDF polymer, resulting from the dehydrofluorination process. The crystallization temperature and melting temperature for both pristine PVDF and dPVDF were similar, indicating no substantial inter-molecular cross-linking within the dPVDF polymer. The fabricated dPVDF membranes were more hydrophobic (water contact angle, WCA ≈ 115°) than the similarly fabricated PVDF membranes (WCA ≈ 99°), yet had greater equilibrium water content (EWC) and porosity (ε), which correlated to the morphology of the fabricated membranes. The dPVDF membranes with 30 wt% PVP not only demonstrated stability in a caustic environment (1 M NaOH for 90 min), but also had a pure water flux of ~4300 L m−2 h−1, within the range of commercially available PVDF membranes (~6300–8100 L m−2 h−1). Thus, with commercially relevant fluxes, increased caustic resistance, and pendant alkene groups for post-modification these DIW dehydrofluorinated membranes offer an exciting new potential for a broad range of applications.

Modification Approaches to Enhance Dehydration Properties of Sodium Alginate-Based Pervaporation Membranes.

Transport characteristics of sodium alginate (SA) membranes cross-linked with CaCl2 and modified with fullerenol and fullerene derivative with L-arginine for pervaporation dehydration were improved applying various approaches, including the selection of a porous substrate for the creation of a thin selective SA-based layer, and the deposition of nano-sized polyelectrolyte (PEL) layers through the use of a layer-by-layer (Lbl) method. The impacts of commercial porous substrates made of polyacrylonitrile (PAN), regenerated cellulose, and aromatic polysulfone amide were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), standard porosimetry method, and water filtration. The effects of PEL combinations (such as poly(sodium 4-styrene sulfonate) (PSS)/SA, PSS/chitosan, PSS/polyacrylic acid, PSS/poly(allylamine hydrochloride)) and the number of PEL bilayers deposited with the Lbl technique on the properties of the SA and SA/fullerene derivative membranes were studied by SEM, AFM, and contact angle measurements. The best characteristics were exhibited by a cross-linked PAN-supported SA/fullerenol (5%) membrane with five PSS/SA bilayers: permeation flux of 0.68–1.38 kg/(m2h), 0.18–1.55 kg/(m2h), and 0.50–1.15 kg/(m2h), and over 99.7, 99.0, and 89.0 wt.% water in the permeate for the pervaporation dehydration of isopropanol (12–70 wt.% water), ethanol (4–70 wt.% water), and tetrahydrofuran (5.7–70 wt.% water), respectively. It was demonstrated that the mutual application of bulk and surface modifications essentially improved the membrane’s characteristics in pervaporation dehydration.

Development of technology for modification of heat-resistant nickel alloy ЖС3ДК-ВІ with titanium carbonitride ultrafine powders

Purpose. To study the effect of modification by the titanium carbonitride Ti(C, N) ultrafine particles additives in the form of powder and briquettes on the structure and physical-mechanical properties of the ЖС3ДК-ВІ alloy used for the manufacture of aircraft engine turbines cast rotor blades.
 Research methods. Preliminary high-temperature treatment of the melt was carried out on a VIP-10 installation.
 On the UPPF-3M installation with the alkaline melting pot, the ЖС3ДК-ВІ alloy was modified with ultrafine particles of titanium carbonitride Ti(C,N) in an amount of 60...80 g in the form of briquettes or powder wrapped in nickel foil.
 The samples were subjected to homogenization at a temperature of 1210 °C with a holding time of 3.5 hours and air cooling.
 The chemical composition of investigated alloys was determined. The macrostructure was studied on plates ~ 4 mm thick after chemical etching. The microstructure was evaluated on microsections before and after etching in the Marble reagent.
 Microhardness, ultimate strength, elongation and contraction, impact strength were determined at room temperature. Long-term strength tests were carried out at 850 °C under a load of 350 MPa. The bending test of the blades was carried out on a manual screw press in accordance with GOST 14019-80.
 Results. The microstructure of Ti+TiCN briquettes has been studied by optical and electron microscopy. X-ray microanalysis of specimen fractures confirmed a fairly uniform distribution of titanium carbonitride in the volume of briquettes.
 The chemical composition, macro- and microstructure of the experimental alloy have been studied. A fracto-graphic study of the samples fracture structure was carried out.
 The modifying effect of titanium carbonitride ultrafine particles on the dendritic structure, distribution and change in the morphology of primary carbides, the number and distribution of carbonitride particles has been established.
 A comparative analysis of the mechanical and heat-resistant properties of the ЖС3ДК-ВІ alloy of standard composition and modified with ultradispersed Ti(C,N) particles has been carried out. Bending tests of turbine rotor blades were carried out.
 Scientific novelty. It is shown that the use of ultrafine titanium carbonitride powders for bulk modification of the heat-resistant nickel alloy ЖС3ДК-ВІ makes it possible to increase the mechanical and heat-resistant properties of the material. Increasing the amount of modifier promotes grain refinement.
 More stable properties and favorable structure are provided by melt modification with ultrafine Ti(C,N) particles in the form of briquettes. It was found that modification with powdered Ti(C,N) leads to a decrease in the impact toughness values due to the formation of boundary microporosity.
 Practical value. The technology of the heat-resistant nickel alloy ЖС3ДК-ВІ, used for the manufacture of cast rotor blades of gas turbine engines, modification with additives of titanium carbonitride Ti(C,N) ultrafine particles, providing an increased level of performance properties of finished products, has been developed.

Novel Membranes Based on Hydroxyethyl Cellulose/Sodium Alginate for Pervaporation Dehydration of Isopropanol.

Membrane methods, especially pervaporation, are quickly growing up. In line with that, effective membrane materials based on biopolymers are required for the industrially significant mixtures separation. To essentially improve membrane transport characteristics, the application of the surface or/and bulk modifications can be carried out. In the present study, novel dense and supported membranes based on hydroxyethyl cellulose (HEC)/sodium alginate (SA) were developed for pervaporation dehydration of isopropanol using several approaches: (1) the selection of the optimal ratio of polymers, (2) the introduction of fullerenol in blend polymer matrix, (3) the selection of the optimal cross-linking agent for the membranes, (4) the application of layer-by-layer deposition of polyelectrolytes on supported membrane surface (poly(sodium 4-styrenesulfonate) (PSS)/poly(allylamine hydrochloride) (PAH) and PSS/SA). Structural and physicochemical characteristics of the membranes were analyzed by different methods. A cross-linked supported membrane based on HEC/SA/fullerenol (5%) composite possessed the following transport characteristics in pervaporation dehydration of isopropanol (12–50 wt.% water): 0.42–1.72 kg/(m2h) permeation flux, and 77.8–99.99 wt.% water content in the permeate. The surface modification of this membrane with 5 bilayers of PSS/PAH and PSS/SA resulted in the increase of permeation flux up to 0.47–3.0 and 0.46–1.9 kg/(m2h), respectively, with lower selectivity.

Recent advances in surface modification of biopolymeric nanofibrous scaffolds

Nanofibrous biomaterials, because of their structural similarity to the extracellular matrix, can be employed as a scaffold in tissue engineering. The use of biopolymers to nanofibers fabrication attracts a great deal of attention. However, sometimes these nanofibers do not support specific cell behaviors. To address this drawback, surface modification of these structures has been actively investigated. Just a while ago, nanofibrous scaffolds have been modified employing various techniques to provide an appropriate microenvironment for protecting cell functions. Modification of bulk or surfaces of the nanofibrous scaffolds via different methods can promote cell adhesion, growth, proliferation, migration, and differentiation. In this paper, we are going to discuss the different and new approaches to surface modification of polymeric nanofibers that can influence scaffolds characteristics.

Nanostructured Bulk Titanium with Enhanced Properties—Strategies and Prospects for Dental Applications

Nanostructuring delivers significant enhancement of Ti mechanical strength and reduces the size of dental implants while avoiding undesirable alloying elements such as Al or V. Implant miniaturization is vital for patients who lack the space in the oral cavity for standard replacements. Herein, a number of strategies proposed in recent years are summarized to optimize the properties of nanostructured Ti products in respect of dental applications: bulk modifications, surface modifications, and deposition of bioactive coatings. Insight into how changes in microstructure induced by the process of fabricating nanograined Ti may be successfully exploited to improve surface properties, which are an essential feature of modern dental healthcare, is provided.

Correction: In situ surface modification of bulk or nano materials by cytochrome-c for active hydrogen evolution catalysis

Correction for ‘In situ surface modification of bulk or nano materials by cytochrome-c for active hydrogen evolution catalysis’ by Pallavi Thakur et al., Mater. Chem. Front., 2021, 5, 1295–1300, DOI: 10.1039/D0QM00627K.

Surface Nanostructuring of a CuAlBe Shape Memory Alloy Produces a 10.3 ± 0.6 GPa Nanohardness Martensite Microstructure.

Severe plastic deformation (SPD) has led to the discovery of ever stronger materials, either by bulk modification or by surface deformation under sliding contact. These processes increase the strength of an alloy through the transformation of the deformation substructure into submicrometric grains or twins. Here, surface SPD was induced by plastic deformation under frictional contact with a spherical tool in a hot rolled CuAlBe-shape memory alloy. This created a microstructure consisting of a few course martensite variants and ultrafine intersecting bands of secondary martensite and/or austenite, increasing the nanohardness of hot-rolled material from 2.6 to 10.3 GPa. In as-cast material the increase was from 2.4 to 5 GPa. The friction coefficient and surface damage were significantly higher in the hot rolled condition. Metallographic evidence showed that hot rolling was not followed by recrystallisation. This means that a remaining dislocation substructure can lock the martensite and impedes back-transformation to austenite. In the as-cast material, a very fine but softer austenite microstructure was found. The observed difference in properties provides an opportunity to fine-tune the process either for optimal wear resistance or for maximum surface hardness. The modified hot-rolled material possesses the highest hardness obtained to date in nanostructured non-ferrous alloys.

Complete Prevention of Contact Electrification by Molecular Engineering

Summary Electrostatic charges are easily generated on surfaces during contact electrification. Although these invisible charges have emerged as a new dimension in mediating the functions of surfaces, such as energy conversion, liquid transport, reactivity, and adsorbability, the accumulation of charges on surfaces can also pose many undesirable consequences. Despite notable progress, existing approaches in engineering antistatic surfaces suffer from limitations such as the need to modify bulk materials or for delicate control of patterning on surfaces that rely on the neutralization of generated charges. Herein, we report a general toolbox for designing antistatic coatings by leveraging on chemically heterogeneous components with electron-donating and electron-accepting functions, i.e., N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and 1H,1H,2H,2H-perfluorooctyl trimethoxysilane, to molecularly engineer the surface potential to achieve an electrostatic homogeneity and completely prevent charge generation. Our approach is general, which allows the facile fabrication of antistatic coatings on various materials, even flexible and curved, with good re-writability and transparency.

Surface modification of cellulose nanofiber film with fatty acids for developing renewable hydrophobic food packaging

Abstract Cellulose Nanofibers (CNF) have been increasingly investigated as an alternative to plastic packages. Despite their excellent mechanical properties, their hydrophilic nature affects their application as a food packaging component. Chemical modification can improve their hydrophobicity, but result in films with the poor mechanical property. In this study, we investigated the modification of premade CNF films with saturated fatty acids lauric, palmitic, and stearic acids using modification techniques that aimed to preserve mechanical property while maintaining hydrophobicity. Two modification techniques were followed: bulk modification, where the entire film was exposed to the reaction medium and surface modification where only one of the surfaces of the CNF film was exposed. The resulting films were investigated for their proof of modification, mechanical and water vapor barrier property, surface free energy, crystallinity, and their thermal stability. Both modification techniques resulted in films with increased surface hydrophobicity; the films that were formed through bulk modification of CNF improved its water vapor barrier property significantly (p

Porous Co3O4 modified carbon paste electrode for the quantification of dopamine

A simple Co3O4 modified carbon paste electrode (CPE) was developed as an electrochemical sensor for the selective detection and quantification of dopamine (DA) via fastest synthesis and fabrication methods. The solution combustion method and bulk modification techniques were sequentially used for the preparation of the sensor. The modifier was characterized using different techniques such as PXRD, FT-IR, SEM and TG-DSC. The fabricated sensor shows a wide linear dynamic range of 80 µM-300 nM, low detection limit, excellent reproducibility and high stability. The differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques were extensively used for the electrochemical studies. The same electrode was used for detecting DA in the solution of coexisting ascorbic acid (AA) and uric acid (UA). Well resolved peaks and good current sensitivity of this electrochemical sensor extended its utility in determining DA in blood serum at physiological pH.

Investigating material modification in a heretofore unexplored laser regime

Beyond the critical power for self-focusing, ultrashort pulses unexpectedly yield stable bulk modifications in silica, including photonics-relevant densification.

Bulk-Surface Modification of Nanoparticles for Developing Highly-Crosslinked Polymer Nanocomposites.

Surface modification of nanoparticles with functional molecules has become a routine method to compensate for diffusion-controlled crosslinking of thermoset polymer composites at late stages of crosslinking, while bulk modification has not carefully been discussed. In this work, a highly-crosslinked model polymer nanocomposite based on epoxy and surface-bulk functionalized magnetic nanoparticles (MNPs) was developed. MNPs were synthesized electrochemically, and then polyethylene glycol (PEG) surface-functionalized (PEG-MNPs) and PEG-functionalized cobalt-doped (Co-PEG-MNPs) particles were developed and used in nanocomposite preparation. Various analyses including field-emission scanning electron microscopy, Fourier-transform infrared spectrophotometry (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) were employed in characterization of surface and bulk of PEG-MNPs and Co-PEG-MNPs. Epoxy nanocomposites including the aforementioned MNPs were prepared and analyzed by nonisothermal differential scanning calorimetry (DSC) to study their curing potential in epoxy/amine system. Analyses based on Cure Index revealed that incorporation of 0.1 wt.% of Co-PEG-MNPs into epoxy led to Excellent cure at all heating rates, which uncovered the assistance of bulk modification of nanoparticles to the crosslinking of model epoxy nanocomposites. Isoconversional methods revealed higher activation energy for the completely crosslinked epoxy/Co-PEG-MNPs nanocomposite compared to the neat epoxy. The kinetic model based on isoconversional methods was verified by the experimental rate of cure reaction.