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Heterogeneous catalysis is essential to most industrial chemical processes. To achieve a better sustainability of these processes we need highly efficient and highly selective catalysts that are based on earth-abundant materials rather than the more conventional noble metals. Here, we discuss the potential of inorganic materials as catalysts for chemical transformations focusing in particular on the promising transition metal phosphides and sulfides. We describe our recent and current efforts to understand the interfacial chemistry of these materials that governs catalysis, and to tune catalytic reactivity by controlled chemical modification of the material surfaces and by use of interfacial electric fields.

The widespread utilization of plant cellulose fiber-inorganic fillers-synthetic fabric-reinforced laminates is the current trend in the research field. This investigation studies the effect of chemically treated and untreated water hyacinth/pineapple leaf, titanium carbide nanoparticles, Innegra, and carbon fabric reinforcement on the physical, mechanical, and thermal characteristics of ultra-violet resistant polyester hybrid composites. The chemically treated and untreated water hyacinth/pineapple leaf fibers were examined from Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and found that chemically treated fibers have an excellent interlocking bond with TiC nanoparticles, Innegra, carbon fabric, and polyester matrix. The maximum tensile, flexural, interlaminar shear, impact strength, and shore hardness also affirmed good interfacial bonding of fillers and textiles within the matrix as examined from SEM micrographs. The present investigation also determines the forecasting of the approaches and performance of artificial neural network (ANN) to model the material characteristics of fabricated polyester hybrid composite. Furthermore, the ANN model was more accurate and a valuable technique to optimize the material characteristics of the developed polyester hybrid composite.

Aromatic organic acids are among the common environmental pollutants that enter the water with washouts from agricultural lands, wastewater from chemical and pharmaceutical industries. Taking into account the high toxicity of aromatic substances, the important task of water purification is the removal of their trace amounts. This problem can be solved by using chemically modified inorganic materials, such as silicas, which have high mechanical, chemical, hydrolytic, and radiation stability. Therefore, they do not lose their sorption capacity during long-term use and do not pollute water with sorbent degradation products. The purpose of this work is the synthesis of a sorption-active material for removal of toxic aromatic acids by chemical immobilization of β-cyclodextrin functional groups on an aerosilogel (highly dispersed type of amorphous silica). A β-cyclodextrin-containing aerosilogel was synthesized by two-stage liquid-phase chemical modification of hydroxylated silica surface. Using the methods of IR spectroscopy, spectrophotometry, thermogravimetry, pH metry, low-temperature adsorption-desorption of nitrogen, chemical and elemental analysis of the surface, the surface structure and its quantitative chemical composition, and also parameters of porous structure of initial and chemically modified aerosilogels were determined. Sorption of benzoic, salicylic and β-resorcylic acids on aerosilogels from aqueous buffer solutions with pH=1 was studied. The insignificant contribution of silanol and aminopropyl groups and complete participation of chemically fixed β-cyclodextrin in the sorption of aromatic acids were proved. The results obtained are analyzed using kinetic models for pseudo-first and pseudo-second order processes, as well as Langmuir and Freundlich models for equilibrium adsorption on homogeneous and heterogeneous surfaces. It has been found that the sorption kinetic processes are well described by a pseudo-first order equation (in the presence of one type of functional groups on the surface) and a pseudo-second order equation for bi- and trifunctional aerosilogels. Experimental results on the equilibrium sorption of aromatic acids on β-cyclodextrin-containing aerosilogel are in good agreement with the Langmuir adsorption equation. This is evidence of decisive contribution of grafted oligosaccharide groups to the sorption of organic acids. The proposed chemical approach to increasing the sorption activity of aerosilogel can be used to obtain specific chromatographic carriers, as well as inorganic sorbents for the effective removal of small amounts of highly toxic organic substances from water and aqueous solutions. [ABSTRACT FROM AUTHOR]

Currently, the use of membrane techniques has undergone dynamic growth, particularly due to the diversification of their fields of application. This trend is expected to increase owing to new environmental protection requirements and thanks to the increasingly competitive energy and technical-economic performances offered by membrane processes. New research is constantly being carried out to better understand the functioning of membranes, to create more efficient or more specific membranes, and also to develop processes for new applications. The aim of this work is to improve the performance of a polyamide reverse osmosis membrane by chemical modification of its surface. Thin film polyamide reverse osmosis membranes are widely used for desalination. However, these membranes face a fouling issue that results in low permeation flux, which is undesirable in the reverse osmosis process. An interesting alternative to improve the properties of these polyamide composite membranes is the use of chemical surface modification. In this context, we studied the chemical grafting of vinyl acetate monomer on the surface of a polyamide membrane in order to improve the selectivity towards sodium ion. The chemical grafting was carried out by radical polymerization of vinyl acetate monomer in the presence of benzoil peroxide as an initiator in an organic medium. Unmodified, modified membranes and evolution of the polymerization reaction were analyzed by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), interferometric electron microscopy, and contact angle. An application with a front filtration module was investigated to confirm the improved selectivity for sea water. This study revealed an improved efficiency of the reverse osmosis PA membrane after the grafting of polyacetate monomer on the active layer of this membrane. [ABSTRACT FROM AUTHOR]

New complexing sorbents have been manufactured via chemical surface-modification of highly dispersed boehmite (γ-AlO(OH)) by phosphonic complexones (PCs), namely, by nitrilotri(methylenephosphonic) acid (NTP), 1-hydroxyethane-1,1'-diphosphonic acid (HEDP), N-hydroxyethylimino-N,N-di(methylenephosphonic) acid (HEIDP), and imino-N,N-diacetic-N-methylenephosphonic acid (IDAMP). The manufactured PC–boehmite materials have been characterized by XRD, BET, SEM, TEM, and IR spectroscopy. Modified boehmites, in which the modifier anchor is one of the phosphonic functions of the complexone, exhibit the properties of a complexing support for double-charged metal ions. The kinetic characteristics and sorption capacities of PC–boehmites have been determined. The complexing selectivity on the modified surface are arranged in the following decreasing order: Pb(II) > Cu(II) > Zn(II) ≈ Ni(II) ≈ Co(II) ≈ Cd(II) > Ca(II). The stability of the sorbed state of metal ions changes along the series of surface-anchored complexones in the following order: IDAMP > NTP > HEDP > HEIDP. The trends elucidated point to a close correlation between complexa formation involving phosphonic complexones in solution and on the boehmite surface. [ABSTRACT FROM AUTHOR]

The reduction of silver nitrate with sodium borohydride in the presence of cetyltrimethylammonium bromide yielded stable sols of silver nanoparticles. Their subsequent treatment with cysteamine hydrochloride led to the chemical modification of the surface. Both initial and modified sols were used for the determination of Hg2+ ions in an aqueous medium. The limit of detection for the analyte and the linearity range of the analytical signal for the initial silver sols are lower in comparison with the analogues modified with cysteamine. [ABSTRACT FROM AUTHOR]

Hydrosols of silver nanoparticles chemically modified with cysteine and cysteamine are obtained. Their oxidation with solutions containing active oxygen and chlorine forms is studied. It is shown that the grafted layer of the modifier does not affect the oxidation of the metal core with sodium hypochlorite, but it does have a protective effect in the reaction with hydrogen peroxide. The orders of the reaction for the initial and chemically modified nanoparticles are 1 for sodium hypochlorite, and 0 for hydrogen peroxide. Chemically modified nanoparticles tend to form aggregates. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysis is essential to most industrial chemical processes. To achieve a better sustainability of these processes we need highly efficient and highly selective catalysts that are based on earth-abundant materials rather than the more conventional noble metals. Here, we discuss the potential of inorganic materials as catalysts for chemical transformations focusing in particular on the promising transition metal phosphides and sulfides. We describe our recent and current efforts to understand the interfacial chemistry of these materials that governs catalysis, and to tune catalytic reactivity by controlled chemical modification of the material surfaces and by use of interfacial electric fields., (Copyright 2024 Tzu-Chin Chang Chien, Murielle F. Delley. License: This work is licensed under a Creative Commons Attribution 4.0 International License.)

A method for the surface chemical modification of aluminum oxyhydroxide (boehmite γ-AlO (OH)) by the nitrilotris(methylene phosphonic) acid (NTP) complexing ligand is proposed. The unmodified and NTP-modified boehmites are characterized using X-ray powder diffraction, XPS, and IR spectroscopy; the acid–base and complex-forming properties of surface-grafted NTP are studied. One of the three phosphonic groups of NTP is found to be involved in binding to the boehmite surface. The surface concentration and stepwise dissociation constants of grafted NTP are determined. A study of the nickel(II) sorption as a function of aqueous acidity shows that the modifying coating increases the sorption capacity of boehmite (causing рН50 to shift by one unit toward lower values). In terms of surface complexation theory, nickel(II) sorption from aqueous solutions may be described by models involving ≡Al–ONi+ and ≡Al–ONi(OH) complexes in the case of boehmite and ≡Al–LHi Nii–3 (i = 0, 1, 2, or 3) complexes in the case of NTP-modified boehmite (NTP-boehmite). NTP anchorage to the surface decreases the stability of nickel(II) complexes compared to their analogues in solutions. A mechanism of nickel(II) ion binding by NTP-boehmite is suggested. The prepared new organomineral support can be used to immobilize those metal ions that form stable complexes with phosphonic acids. [ABSTRACT FROM AUTHOR]

The recent emergence of bio-based nanocomposites makes perfect sense from a technical and environmental point of view. Cellulose nanocrystals (CNCs) are novel bio-based nanomaterials with a wide range of beneficial properties. Their biodegradability, crystallinity, high surface area, and mechanical strength, as well as their highly reactive surface, make them ideal materials as nanofillers in polymeric matrices. However, most the bio-based polymers are hydrophobic, and the hydrophilicity of CNC is therefore a challenge to their incorporation in such matrices. In this study, a new procedure for surface modification of CNC with long aliphatic chains [lauric acid (12 carbons) and stearic acid (18 carbons)] was developed that limits the use of petro-chemicals and facilitates their potential recycling. A study of the dispersion state of CNC in acetone was performed first. Then, grafting efficiency was highlighted by several techniques and quantification of the amount of grafted fatty chains was investigated. Degrees of substitution on the bulk and on the surface of the CNC were calculated between 0.1 and 0.3, which provided enough grafted functions to confer hydrophobic behavior to modified CNCs, as highlighted by the increasing of contact angle from 65° for neat CNC to 80° after modification. Finally, conservation of CNC crystalline structure and morphology was proved by both X-ray diffraction and transmission electron microscopy analyses. Modified CNCs exhibit a crystallinity index close to 86% and length of approximately 350 nm. Thus, crystalline hydrophobic cellulosic nanomaterials were prepared using a more environmentally friendly procedure than those classically found in the literature. [ABSTRACT FROM AUTHOR]

The conditions of chemical modification of the surface of synthetic magnetic iron oxides (magnetite Fe3O4, maghemite γ-Fe2O3) by phosphonic complexones (PBTC, HEDP, HEIDPH, NTMP, EDTMP) are studied. It is shown that the maximum concentration of grafted groups is observed upon treating iron oxides with aqueous solutions of complexones containing two or three phosphonic groups at pH 2–3 and temperature of 50–60°C for 2–6 h. To characterize the grafted layer, various physicochemical research methods (XRD, FTIR spectroscopy, the BET method, thermal analysis, acid–base titration, sorption from solutions) were used. It is found that the modifying coating significantly increases the sorption ability of magnetic iron oxides towards metal cations (Cu(II), Cd(II)). A mechanism for binding of metal ions by modified sorbents is proposed. [ABSTRACT FROM AUTHOR]

The interaction of Ag+ ions existing on the surface of silver nanoparticles with complexing agents, such as ammonia, ammonium thiocyanate, and sodium thiosulfate, has been studied. Both the presence of complexing agents in the initial reaction mixture and their introduction into preliminarily synthesized sols of silver nanoparticles lead to a small shift of the absorption maximum toward long wavelengths and its considerable broadening. In both cases, there is a correlation of the absorption band width with the logarithm of formation constants of corresponding silver complexes. This can be evidence of analogous chemical processes that occur on the surface of nanoparticles. The surface complexation is of interest both for a fundamental understanding of the interaction nature and in the applied aspect for the determination of complexing agents in aqueous systems. [ABSTRACT FROM AUTHOR]

We fabricate crystalline dendritic gold (Au‐D) via a simple electrochemical method and characterize it using several techniques. Chemical modification by self‐assembled thiol molecules on the Au‐D is used to adjust the chemical environment of the substrate surface and to improve surface‐enhanced Raman scattering (SERS) performance. First, the Au‐D modified with different length chains of n‐alkyl thiols cause an enhancement of SERS, which follows a relationship of normalized intensity, IIo, versus (1 + dr) with a slope of −10 according to the electromagnetic mechanism. Subsequently, phenyl thiols with various end‐functional groups are attached to study the effect of chemical modification on SERS enhancement. The results indicate that the 4‐methylthiophenol‐ and thiophenol‐modified substrates do not exhibit significant SERS enhancement, resulting in intensity being dependent on distance. It is worth noting that the 4‐mercaptophenol‐ and 4‐aminothiophenol‐modified surfaces have an effective electric field effect and strong interaction with polarity probe molecules, and they produce a more intense signal than do bare Au‐D particles. [ABSTRACT FROM AUTHOR]

The review is devoted to the analysis of publications on the synthesis and chemical modification of the surface of silver and gold nanoparticles and their use in chemical and biochemical analysis by spectrometry. The formation and subsequent modification of the chemical composition of the surface layer of nanoparticles ensures the solution of problems of the group and individual determination of analytes, i.e., metal ions and organic and bioorganic compounds. The presence of an accessible well-developed surface bearing functional groups of different nature in combination with the effects of surface plasmon resonance and enhanced and surface-enhanced Raman scattering opens wide prospects for the application of nanoparticles to chemical and biochemical analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Date seed derived biochar production via slow pyrolysis. • Chemically modified activated carbons are derived from date seed using H 2 SO 4 as an activating agent. • Capacitive performance is highly affected by the ordered structure of biochar-based materials. The main aim of this research work is to make activated carbon (AC) materials based on biochar obtained from date seeds via pyrolysis and activated with H 2 SO 4. The study aimed to assess the potential of these biochar-based materials for energy storage in supercapacitor by investigating the impact of different activation temperatures on their electrochemical performance in an alkaline electrolyte. The focus was on identifying the most efficient material. Results from Raman Spectroscopy and XRD analysis revealed that sample DSAC-700 exhibited more ordered domains and suitable storage sites compared to the other biochar-based materials. Measured value of the ratio of intensity of D & G band (I D /I G) for DSBC-600, DSAC-700, DSAC-800, and DSAC-900 were 1.13, 0.83, 1.06, and 1.04, respectively. The lowest value of (I D /I G) for DSAC-700 indicated a higher ordered graphitic plane, resulting improved conductivity and diffusion of ions within the aligned graphitic domains, which positively impacted the electrochemical performance. Samples DSAC-700 showed 487.5 F/g specific capacitance at 1 A/g current density. Galvanic charge and discharge trends also showed that DSAC-700 had higher charge storage ability with less discharge. The biochar-based materials (BC and ACs) derived from DS showed promise as materials for energy storage applications, and they represent a step towards clean energy. [ABSTRACT FROM AUTHOR]

A natural zeolite of Kazakh origin, as well as its three different types of chemically modified versions, were assessed from the point of view of permanganate removal yield from aqueous solutions. Modification was carried out by means of di-dodecyl-dimethyl-ammonium bromide surfactant treatment type (1). Types (2) and (3) were treated prior to DDAB wth HCl or NaCl, respectively. All sorbents display broad ranges of particle size distribution. Modification of the natural form enhances the specific surface as well as the pore volume, yet influences not in the same way the sorption yield. The process is slow, however, short- and long-term effectiveness are affected by preparation procedures. The most promising yield is exhibited by the natural zeolite that was subject to a combined acid - surfactant treatment. [ABSTRACT FROM AUTHOR]

The main object of this research is chemical modification of the nanofibrillated cellulose (NFC) surface with a phenanthridinium silane salt to develop durable non-leaching antibacterial surface. Initially, (3-trimethoxysilylpropyl) phenanthridinium iodide (TMSPhI) as an antibacterial agent was synthesized using (3-chloropropyl trimethoxysilane) (CPTMS) and phenanthridine in the presence of potassium iodide. Subsequently, NFC was cationized by reaction of its hydroxyl groups with the trimethoxysilane group of TMSPhI to prepare the modified sample (NFC-TMSPhI). The synthesized TMSPhI was characterized by FT-IR, 1 H and 13 C NMR spectroscopies. The modified NFC samples were also characterized by FE-SEM/EDX, XRD, TGA, elemental analysis, contact angle measurement, FT-IR, UV–Visible and fluorescence spectroscopies. The obtained NFC–TMSPhI samples presented fluorescence property at the maximum emission wavelength in the range of 539-549 nm. Additionally, the antibacterial activity of the modified samples were evaluated quantitatively against Gram-positive ( S . aureus ) and Gram-negative ( E . coli ) bacteria. All the modified samples displayed promising results with at least bacteriostatic effect or bactericidal properties. Finally, the cytotoxic effect of the modified sample on human dermal fibroblasts (HDFs) and two cancer cell lines (MCF-7 and Hela) was investigated that showed dose- and surface charge-dependent toxicity. [ABSTRACT FROM AUTHOR]

Cellulose nanowhiskers (CWs) extracted from cotton fibers were successfully modified with distinct anhydrides structures and used as additives in poly(vinyl alcohol) (PVA) nanocomposite films. The surface modification of CWs was performed with maleic, succinic, acetic or phthalic anhydride to compare the interaction and action the carboxylic groups into PVA films and how these groups influence in mechanical properties of the nanocomposites. CWs presented a high degree of crystallinity and good dispersion in water, with average length at the nanoscale. The addition of specific amounts (3, 6 and 9 wt.%) of modified-CWs increased up to 4.4 times the storage modulus (PVA88-CWSA 9 wt.%), as observed from dynamic mechanical analysis (DMA), compared to the bare PVA films. A significant increase in mechanical properties such as tensile strength, elastic modulus, and elongation at break showed a close relationship to the amount and chemical surface characteristics of CWs added, suggesting that these modified-CWs could be explored as reinforcement additives in PVA films. [ABSTRACT FROM AUTHOR]

By coating surfaces with nano-crystalline diamond (NCD) particles, hydrophilicity can be altered via sidechain modifications without affecting surface texture. The present study aimed to assess the impact of NCD hydrophilicity on machined and rough SLA titanium discs on soft tissue integration, using a rodent model simulating submerged healing. Four different titanium discs (machined titanium = M Titanium, NCD-coated hydrophilic machined titanium = M-O-NCD, sand blasted acid etched (SLA Titanium) titanium, and hydrophilic NCD-coated SLA titanium = SLA O-NCD) were inserted in subdermal pockets of 12 Wistar rats. After one and four weeks of healing, the animals were sacrificed. Biopsies were embedded in methyl methacrylate (MMA), and processed for histology. The number of cells located within a region of interest (ROI) of 10 μm around the discs were counted and compared statistically. Signs of inflammation were evaluated descriptively employing immunohistochemistry. At one week, M-O-NCD coated titanium discs showed significantly higher amounts of cells compared to M Titanium, SLA Titanium, and SLA-O-NCD (p < 0.001). At four weeks, significant higher cell counts were noted at SLA-O-NCD surfaces (p < 0.01). Immunohistochemistry revealed decreased inflammatory responses at hydrophilic surfaces. Within the limits of an animal study, M-O-NCD surfaces seem to stimulate cell proliferation in the initial healing phase, whereas SLA-O-NCD surfaces appeared advantageous afterwards. [ABSTRACT FROM AUTHOR]

This study presents a comparison of two types of bifunctional structured surface that were made from the same polymer –– an antimicrobial polycation (a synthetic mimic of an antimicrobial peptide, SMAMP) and a protein-repellent polyzwitterion (poly(sulfobetaines), PSB). The first type of bifunctional surface was fabricated by a colloidal lithography (CL) based process where the two polymers were immobilized sequentially onto pre-structured surfaces with a chemical contrast (gold on silicon). This enabled site-selective covalent attachment. The CL materials had a spacing ranging from 200 nm to 2 µm. The second type of structured surface (spacing: 1 – 8.5 µm) was fabricated using a microcontact printing (µCP) process where SMAMP patches were printed onto a PSB network, so that 3D surface features were obtained. The thus obtained materials were studied by quantitative nanomechanical measurements using atomic force microscopy (QNM-AFM). The different architectures led to different local elastic moduli at the polymer-air interface, where the CL surfaces were much stiffer (Derjaguin-Muller-Toporov (DMT) modulus = 20 ± 0.8 GPa) compared to the structured 3D networks obtained by µCP (DMT modulus = 42 ± 1.1 MPa). The effects of the surface topology and stiffness on the antimicrobial activity against Escherichia coli, the protein repellency (using fibrinogen), and the compatibility with human gingival mucosal keratinocytes were investigated. The softer 3D µCP surfaces had simultaneous antimicrobial activity, protein repellency, and cell compatibility at all spacings. For the stiffer CL surfaces, quantitative simultaneous antimicrobial activity and protein repellency was not obtained. However, the cell compatibility could be maintained at all spacings. The optimum spacing for the CL materials was in the range of 500 nm–1 µm, with significantly reduced antimicrobial activity at 2 µm spacing. Thus, the soft polymer network obtained by µCP could be more easily optimized than the stiff CL surface, and had a broader topology range of optimal or near-optimal bioactivity.

Owing to excellent mechanical property and biodegradation, magnesium-based alloys have been widely investigated for temporary implants such as cardiovascular stent and bone graft; however, the fast biodegradation in physiological environment and the limited surface biocompatibility hinder their clinical applications. In the present study, magnesium alloy was treated by sodium hydroxide (NaOH) and hydrogen fluoride (HF) solutions, respectively, to produce the chemical conversion layers with the aim of improving the corrosion resistance and biocompatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that the chemical conversion layers of magnesium hydroxide or magnesium fluoride were obtained successfully. Sodium hydroxide treatment can significantly enhance the surface hydrophilicity while hydrogen fluoride treatment improved the surface hydrophobicity. Both the chemical conversion layers can obviously improve the corrosion resistance of the pristine magnesium alloy. Due to the hydrophobicity of magnesium fluoride, HF-treated magnesium alloy showed the relative better corrosion resistance than that of NaOH-treated substrate. According to the results of hemolysis assay and platelet adhesion, the chemical surface modified samples exhibited improved blood compatibility as compared to the pristine magnesium alloy. Furthermore, the chemical surface modified samples improved cytocompatibility to endothelial cells, the cells had better cell adhesion and proliferative profiles on the modified surfaces. Due to the excellent hydrophilicity, the NaOH-treated substrate displayed better blood compatibility and cytocompatibility to endothelial cells than that of HF-treated sample. It was considered that the method of the present study can be used for the surface modification of the magnesium alloy to enhance the corrosion resistance and biocompatibility. [ABSTRACT FROM AUTHOR]

In practical applications, cyclic heating and high temperature will worsen the stability of nanofluids. To enhance the practical application of nanofluids for mid-temperature solar collectors, WO 2.9 nanoparticles were modified by hexadecyl trimethoxysilane and the corresponding heat-transfer-oil-based nanofluids was prepared for mid-temperature solar collecting. Stability of nanofluids was evaluated by static observation, Zeta potential and thermal shock experiments at 200 °C. The results showed that nanofluids with mass fractions up to 4 wt% remained static stability beyond 5 weeks and 0.85 wt% nanofluids had thermal shock stability at 200 °C for over 2 weeks. This excellent performance makes them a suitable long-term working fluid medium for solar mid-temperature collectors. The increase in thermal conductivity also enhances the thermal performance of systems in industrial processes. It's noteworthy that preliminary exploration of the cyclic thermal stability mechanism of nanofluids provides a reference for further research on thermal shock stability of nanofluids in actual services. [Display omitted] • Hexadecyl trimethoxysilane is used to improve the stability of nanofluids. • The self-condensation products are beneficial to the stability of nanofluids. • Nanofluids with mass fractions up to 4% remain stable after 5 weeks of resting. • The nanofluids remain stable after thermal shock experiment at 200 °C for 2 weeks. • The nanofluids can be used in solar mid-temperature collectors for a long time. [ABSTRACT FROM AUTHOR]

Interest in nanofibrillated cellulose (NFC) has increased notably over recent decades. This bio-based nanomaterial has been used essentially in bionanocomposites or in paper thanks to its high mechanical reinforcement ability or barrier property respectively. Its nano-scale dimensions and its capacity to form a strong entangled nanoporous network have encouraged the emergence of new high-value applications. It is worth noting that chemical surface modification of this material can be a key factor to achieve a better compatibility with matrices. In order to increase the compatibility in different matrices or to add new functions, surface chemical modification of NFC appears to be the prior choice to conserve its intrinsic nanofibre properties. In this review, the authors have proposed for the first time an overview of all chemical grafting strategies used to date on nanofibrillated cellulose with focus on surface modification such as physical adsorption, molecular grafting or polymer grafting.

By coating surfaces with nano-crystalline diamond (NCD) particles, hydrophilicity can be altered via sidechain modifications without affecting surface texture. The present study aimed to assess the impact of NCD hydrophilicity on machined and rough SLA titanium discs on soft tissue integration, using a rodent model simulating submerged healing. Four different titanium discs (machined titanium = M Titanium, NCD-coated hydrophilic machined titanium = M-O-NCD, sand blasted acid etched (SLA Titanium) titanium, and hydrophilic NCD-coated SLA titanium = SLA O-NCD) were inserted in subdermal pockets of 12 Wistar rats. After one and four weeks of healing, the animals were sacrificed. Biopsies were embedded in methyl methacrylate (MMA), and processed for histology. The number of cells located within a region of interest (ROI) of 10 µm around the discs were counted and compared statistically. Signs of inflammation were evaluated descriptively employing immunohistochemistry. At one week, M-O-NCD coated titanium discs showed significantly higher amounts of cells compared to M Titanium, SLA Titanium, and SLA-O-NCD (p < 0.001). At four weeks, significant higher cell counts were noted at SLA-O-NCD surfaces (p < 0.01). Immunohistochemistry revealed decreased inflammatory responses at hydrophilic surfaces. Within the limits of an animal study, M-O-NCD surfaces seem to stimulate cell proliferation in the initial healing phase, whereas SLA-O-NCD surfaces appeared advantageous afterwards.

The surface grafting of cellulose nanocrystals (CNC) is a valuable tool to increase opportunities for their application. This work had several goals designed to improve CNC: reduction of hornification, increased re-dispersibility after CNC drying, and tuning of the surface graft to enhance the adsorption of particular molecules. To achieve this, the CNC surfaces were modified chemically with aromatic surface grafts using widely employed methods: the creation of urethane linkages, silylation and esterification. Even a low degree of grafting sufficed to increase water contact angles to as much as 96°. The analysis of water sorption isotherms showed that at high water activities, capillary condensation could be suppressed and hysteresis was decreased. This indicates that hornification was significantly suppressed. However, although the contact angles increased, the water sorption isotherms were changed only slightly because of reduced hysteresis. The grafts were not able to shield the surface from water vapour sorption. A comparison of the sorption isotherms of anisole and cyclohexane, sorbates with a similar surface area, showed that the sorption of anisole was three times higher than that of cyclohexane. The specific sorption of aromatic molecules was achieved and the most efficient methodology was the esterification of CNC with carboxylic acids containing a flexible linker between the aromatic moiety and ester bond. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stable binary nanofluids were prepared by surface modification with coupling agent. • Working condition was simulated by interval heating as well as magnetic stirring. • Thermal conductivity of nanofluids decreased within 3.5% after standing for 14 days. • Nanofluids remain stable after cyclic thermal shock experiment at 90 ℃ for 14 days. Binary nanofluid has excellent heat transfer performance and spectral selective absorption characteristic. However, when nanofluid is applied to actual systems, it is subject to severe thermal shock, which leads to quick agglomeration and therefore deterioration of the performances. This study aims to investigate the stability of tungsten oxide (WO 2.9)-silicon carbide (SiC) binary nanofluid in actual service environment. The surface of nanoparticles was chemically modified by the coupling agent method, and the process was optimized. Then, the binary nanofluid was prepared with the optimal process of unitary nanofluid and the improved two-step method. And the actual working condition was simulated by interval heating as well as magnetic stirring. Finally, the preparation process was optimized further from the aspects of particle size, particle concentration, and thermal shock temperature. The results show that the binary nanofluid prepared by the optimum preparation process can maintain great stability after cyclic thermal shock experiment at 90 ℃ for 14 days, which put a foundation for the application of binary nanoparticles into solar beam splitting and enhance its practicality. [ABSTRACT FROM AUTHOR]

Owing to excellent mechanical property and biodegradation, magnesium-based alloys have been widely investigated for temporary implants such as cardiovascular stent and bone graft; however, the fast biodegradation in physiological environment and the limited surface biocompatibility hinder their clinical applications. In the present study, magnesium alloy was treated by sodium hydroxide (NaOH) and hydrogen fluoride (HF) solutions, respectively, to produce the chemical conversion layers with the aim of improving the corrosion resistance and biocompatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that the chemical conversion layers of magnesium hydroxide or magnesium fluoride were obtained successfully. Sodium hydroxide treatment can significantly enhance the surface hydrophilicity while hydrogen fluoride treatment improved the surface hydrophobicity. Both the chemical conversion layers can obviously improve the corrosion resistance of the pristine magnesium alloy. Due to the hydrophobicity of magnesium fluoride, HF-treated magnesium alloy showed the relative better corrosion resistance than that of NaOH-treated substrate. According to the results of hemolysis assay and platelet adhesion, the chemical surface modified samples exhibited improved blood compatibility as compared to the pristine magnesium alloy. Furthermore, the chemical surface modified samples improved cytocompatibility to endothelial cells, the cells had better cell adhesion and proliferative profiles on the modified surfaces. Due to the excellent hydrophilicity, the NaOH-treated substrate displayed better blood compatibility and cytocompatibility to endothelial cells than that of HF-treated sample. It was considered that the method of the present study can be used for the surface modification of the magnesium alloy to enhance the corrosion resistance and biocompatibility.

One of the techniques for a reduction in particle cohesiveness is the admixing of nano-particles. However, the mechanism of cohesiveness reduction has not yet been clarified. In this study we focused on a compressed packing fraction as one of the values reflecting the cohesiveness and flowability in a compressed particle flow. In order to estimate the mechanism of the reduction, the effects of an adhesive force of admixed particles on the packing fraction were investigated experimentally. In the experiments, silica particles with 397 and 8 nm diameters were used as the main and the admixed particles, respectively. The surfaces of the admixed particles were modified chemically in order to vary their adhesive force with maintaining morphological and mechanical characteristics. At more than 2.0% mixing mass ratios, the decreasing rate with increasing the mass ratio in net difference value of packing fraction for modified admixed particles was smaller than that for the raw particles. A calculation of the packing fraction of the admixed particles in the voids of main particles revealed that difference of the decreasing rates could be attributed to the difference of cohesivenesses between raw and modified admixed particles. The maximum packing fraction achieved by the modified admixed particles was lower than that achieved by the raw admixed particles. However, when a mixture of main and admixed particles was packed by tapping, the packing fraction with modified admixed particles was higher than that with raw admixed particles. This implied that the adequate adhesive force of admixed particles is different by the applied compression force value. [ABSTRACT FROM AUTHOR]

In this study surface-modified nanofibrillated cellulose (NFC) was used at low levels (0.5 to1.5 wt%) as a reinforcement in a polyvinyl alcohol (PVA) matrix. The modified-NFC-PVA composite films prepared using the solution casting technique showed improved mechanical performance. Birch pulp cellulose was initially modified by allylation using a solvent-free, dry modification method followed by subsequent epoxidation of the allyl groups and finally grinding the pulp to yield epoxy-NFC. In order to obtain optimal mechanical performance, epoxy-NFC with different degrees of substitution was evaluated in the reinforcement of PVA. The addition of 1 wt% epoxy-NFC (degree of substitution, DS 0.07) enhanced the modulus, strength, and strain of pure PVA film by 307, 139 and 23 %, respectively, thus producing the best performing film. The results demonstrate the favourable effect of chemically functionalized NFC on the mechanical properties of polyvinyl alcohol compared to unmodified NFC as reinforcement. In order to improve industrial and economic feasibility, the manufacture of the composite was also done in situ by grinding cellulose directly in PVA to produce the new biocomposite in a one-step process. [ABSTRACT FROM AUTHOR]

The conversion of the cellular prion protein (PrPC) into aggregated ß-oligomeric (PrPß) and fibril (PrPSc) forms is the central element in the development of prion diseases. Here we report the first use of isotopically-coded hydrogen peroxide surface modification combined with mass spectrometry (MS) for the differential characterization of PrPC and PrPβ. 16O and 18O hydrogen peroxide were used to oxidize methionine and tryptophan residues in PrPC and PrPβ, allowing for the relative quantitation of the extent of modification of each form of the prion protein. After modification with either light or heavy forms of hydrogen peroxide (H2 16O2 and H2 18O2), the PrPC and PrPβ forms of the protein were then combined, digested with trypsin, and analysed by LC-MS. The 18O/16O signal intensity ratios were used to determine the relative levels of oxidation of specific amino acids in the PrPC and PrPβ forms. Using this approach we have detected several residues that are differentially-oxidized between the native and β-oligomeric prion forms, allowing determination of the regions of PrPC involved in the formation of PrPβ aggregates. Modification of these residues in the β-oligomeric form is compatible with a flip of the β1-H1-β2 loop away from amphipathic helices 2 and 3 during conversion. Biological significance: Surface modification using isotopically-coded hydrogen peroxide has allowed quantitative comparison of the exposure of methionine and tryptophan residues in PrPC and PrPß forms of prion protein. Detected changes in surface exposure of a number of residues have indicated portions of the PrP structure which undergo conformational transition upon conversion. This article is part of a Special Issue entitled: Can Proteomics Fill the Gap Between Genomics and Phenotypes? [ABSTRACT FROM AUTHOR]

Abstract: Block co-polymer (BCP) lithography is becoming an established technique for patterning beyond optical lithography limitations. It is based on combining the intrinsic property of block co-polymers to phase separate at the molecular scale with the capabilities of conventional top-down lithographic methods for patterning surfaces. Guiding the self-assembly of block co-polymers by surface chemical modification is one of the most used processes to drive the self-assembly in a convenient way. It consists on using lithography and oxygen plasma to create different wettability regions on a polymer brush grafted on the surface. However, the optimal conditions for obtaining a good guiding pattern in chemical surface modification are difficult to find since the ultimate mechanism that causes the guiding is not completely known. We present an investigation about the use of hydroxyl-terminated polystyrene (PS-OH) as a single polymer brush layer for multiple patterning directed self-assembly DSA of PS/PMMA block co-polymers. We achieve pattern multiplication with density increase factors up to ×12 and we demonstrate pattern transfer to silicon. [Copyright &y& Elsevier]

Interest in nanofibrillated cellulose (NFC) has increased notably over recent decades. This bio-based nanomaterial has been used essentially in bionanocomposites or in paper thanks to its high mechanical reinforcement ability or barrier property respectively. Its nano-scale dimensions and its capacity to form a strong entangled nanoporous network have encouraged the emergence of new high-value applications. It is worth noting that chemical surface modification of this material can be a key factor to achieve a better compatibility with matrices. In order to increase the compatibility in different matrices or to add new functions, surface chemical modification of NFC appears to be the prior choice to conserve its intrinsic nanofibre properties. In this review, the authors have proposed for the first time an overview of all chemical grafting strategies used to date on nanofibrillated cellulose with focus on surface modification such as physical adsorption, molecular grafting or polymer grafting. [ABSTRACT FROM AUTHOR]

Abstract: Control over biointerfacial interactions in vitro and in vivo is the key to many biomedical applications: from cell culture and diagnostic tools to drug delivery, biomaterials and regenerative medicine. The increasing use of nanostructured materials is placing a greater demand on improving our understanding of how these new materials influence biointerfacial interactions, including protein adsorption and subsequent cellular responses. A range of nanoscale material properties influence these interactions, and material toxicity. The ability to manipulate both material nanochemistry and nanotopography remains challenging in its own right, however, a more in-depth knowledge of the subsequent biological responses to these new materials must occur simultaneously if they are ever to be affective in the clinic. We highlight some of the key technologies used for fabrication of nanostructured materials, examine how nanostructured materials influence the behavior of proteins and cells at surfaces and provide details of important analytical techniques used in this context. [Copyright &y& Elsevier]

Chemical surface modification of nanofibrillated cellulose (NFC) was performed using a long aliphatic isocyanate chain. Different molar ratios of the coupling agents were tested, i.e., 1, 10, 30 equivalents with respect to hydroxyl groups of the NFC surface. FE-SEM analyses revealed that there were no changes in their morphology thus keeping nanofibril-like structure with about 30 nm of diameter. All these samples were characterized by different techniques (e.g., FTIR) to check the efficiency of the grafting. Hydrophobic NFC were achieved whatever the grafting agent ratio. The Degree of Substitution was determined by Elemental Analyses and the Degree of Substitution of the Surface was calculated thanks to X-ray Photoelectron Spectroscopy data. Combining these two techniques, the Internal Degree of Substitution was proposed for the first time. It indicates if the modification occurs also within NFC internal layers. Surface (contact angle), rheological (water suspension viscosity) and thermal properties (ThermoGravimetric Analysis) of grafted NFC do not follow the expected linear evolution of properties with the increase of molar ratio. X-Ray Diffraction analyses showed that the grafted aliphatic chains display crystalline waxy domains at some ratios. A model for aliphatic chain organization at the surface is proposed and clearly explained for the first time why a compromise in molar ratio is necessary to achieve best properties. [ABSTRACT FROM AUTHOR]

Abstract: In recent years herbicides and heavy metals have surfaced as the most significant environmental pollutants due to rapid industrialization and an increase in population worldwide. While quite effective and efficient, some of the treatment methods, for the removal of these environmental pollutants, involve high operating and maintenance cost along with producing toxic byproducts. Thus, biosorbents have become an attractive alternative to other well established methods. In this study red algae, Gracilaria verrucosa was investigated as a potential biosorbent for the phenoxyalkanoic acid herbicide 2,4-D and the heavy metal Cr(VI). The sorption capacity was found to be 22.3mgg−1 and 113.2mgg−1 respectively. In order to establish the efficiency of G. verrucosa as a biosorbent, sorption tests were conducted with different environmental and process parameters. This study verified that the acid treated biomass, indicates a gradual 47% and 21% increment for 2,4-D and Cr(VI) sorption compared with alkali, formaldehyde, and alcohol treatment. The sorption tests of the red algae G. verrucosa; offer two times more heavy metal removal when compared with low cost biosorbents. Two and three parameter equilibrium models were used to describe the sorption process. Experimental and modeling studies indicate that the sorption process of the investigated sorbents is physisorption with monolayer and endothermic characteristics. Also, surface properties of G. verrucosa were investigated and the effects of the surface active groups were identified. For 2,4 D sorption hydroxyl, carboxyl, and amine and for Cr(VI) sorption hydroxyl, carbonyl, and amino groups were identified as the important surface active groups. [Copyright &y& Elsevier]

The chemical and morphological properties of ramie fibers treated by chemical surface modification were examined with Fourier transform infrared (FT-IR) spectroscopy. The mechanical and thermal decomposition properties were evaluated with respect to tensile strength, tensile modulus and thermogravimetric analysis (TGA). Surface morphological changes were investigated with scanning electron microscopy (SEM). Finally, the capabilities of composites reinforced with various chemically treated fibers were analyzed by investigating tensile and impact strengths. Additionally, the thermal mechanical properties of the composites were investigated with thermal mechanical analysis (TMA). Based on the results of these analyses, we concluded that pectin, lignin and hemicellulose were removed and thermal stability was increased with chemical treatments. The composites reinforced with ramie fiber showed better properties compared with pure PLA matrix with respect to tensile and impact strengths. The peroxide-treated fiber composite had the smallest thermal expansion. [ABSTRACT FROM AUTHOR]

Abstract: Surface modification of polymeric films is a way to obtain final products with high performance for many specific and ad hoc tailored applications, e.g. in functional packaging, tissue engineering or (bio)sensing. The present work reports, for the first time, on the design and development of surface modified ethylene–acrylic acid copolymer (EAA) films with polyaniline (PANI), with the aim of inducing electrical conductivity and potentially enable the electronic control of a range of physical and chemical properties of the film surface, via a new “grafting from” approach. In particular, we demonstrate that PANI was successfully polymerized and covalently grafted onto flexible EAA substrates, previously activated. The final hybrid materials and the corresponding intermediates were fully characterized via FTIR, XPS, SEM–EDAX, mechanical and electrical tests. The mechanical properties of the films are not detrimentally affected by each treatment step, while a significant increase in electrical conductivity was achieved for the new hybrid materials. [Copyright &y& Elsevier]

Modification of wood fiber/flour (WF) surfaces can improve their compatibility with hydrophobic plastic matrices and reduce composite water uptake. WF was esterified with octanoyl chloride and palmitoyl chloride. Modified WF was analyzed by FT-IR. More extensive esterification occurred in highly polar dimethylformamide (DMF) than in much less polar CHCl3 or methyl tert-butyl ether (MTBE). DMF penetrates into the fiber far more than CHCl3 or MTBE, making more –OH groups available for esterification. Increasing the acid chloride chain length from C8 to C16 decreased the mole fraction of esterification. Longer chains cover surface –OH groups, retarding reactions with nearby hydroxyls after esterification. Longer chain acid chlorides also have lower reactivity and penetrate into the hydrophilic wood fiber more slowly. Modified wood flour surfaces were covered by a hydrophobic layer of ester groups (SEM). Modified wood flour surfaces and WF/HDPE composite fracture surfaces were studied by SEM. C8-modified wood flour (60 wt%)/HDPE composites exhibited far less water absorption after 24 h and 216 h immersions compared with unmodified WF (60 wt%)/HDPE composites. Water absorption continues over the 216 h period. Esterified WF/HDPE composites exhibited lower flexural strengths and moduli. In contrast to C8-esterification, the addition of maleated polypropylene (MAPP) to WF/HDPE composites improved composite mechanical performance and gave similar water absorption properties to C8-esterified WF composites. [ABSTRACT FROM AUTHOR]

Abstract: Organosilane self-assembled monolayers (SAMs) with perfluoroalkyl groups (R f) on glass surfaces were used for arraying proteins and cells on chips. Quartz crystal microbalance measurements confirmed the inhibition of protein adsorption on R f-SAM-modified surfaces and showed efficient adsorption on hydroxyl-, carboxyl-, and amino group-modified surfaces. The characteristics of R f-modified surfaces were evaluated using solvent contact angle measurement and Fourier transform infrared (FTIR) spectroscopy. The R f surface was highly water- and oil-resistant, as inferred from the contact angles of water, oleic acid, and hexadecane. Specific peaks of IR spectra were detected in the region from 1160 to 1360cm−1. Etching with dry plasma completely exfoliated the R f-SAM, exposing the underlying intact glass surface. Modification conditions were optimized using contact angle and FTIR measurements. After dry plasma processing, the contact angles of all solvents became undetectable, and the IR peaks disappeared. Micrometer scale protein and cell patterns can be fabricated using the proposed method. Protein adsorption on micropatterned R f-SAM-modified chips was evaluated using fluorescence analysis; protein adsorption was easily controlled by patterning R f-SAM. PC12 and HeLa cells grew well on micropatterned R f-SAM-modified chips. Micropatterning of R f-SAM by dry plasma treatment with photolithography is useful for the spatial arrangement of proteins and cells. [Copyright &y& Elsevier]

In the second part of the article, the subtractive processes—laser etching and cutting—in the presence of liquid water will be reviewed; but the rarely used methods of water assisted/underwater laser processing, such as welding, silicon wafer breaking, surface modification of polymers, pulsed laser deposition, particle formation and water mask defined microstructures fabrication, will also be described. Etching and cutting under water provide better tolerances and smaller heat-affected zone widths and avoid the re-deposition of debris. Irradiation under water results in increased wetting of fluoropolymers, and laser ablation in water vapor provides deposition of highly crystalline hydroxyapatite coatings. Laser irradiation of solid targets in water has been used to fabricate Ag, Au, Ni, Cu and carbon nanoparticles. The results of an original study on the formation of free-standing high aspect ratio Pb(ZrxTi1−x)O3 microplates fabricated by laser irradiation of Pb(ZrxTi1−x)O3 ceramics in water are also reported. The platelets were up to 60 μm in diameter and 50–160 nm in thickness. The use of neutral liquids other than water and some medical applications of underwater/water-assisted laser light driven processes will also be briefly reviewed. [Copyright &y& Elsevier]

The surface structure of modified silica powder has been studied by various experiments and simulations. In addition, the effect of surface structure on wettability has also been investigated. Nonporous silica powder was modified with n-and t-butyl alcohol. Two series of the modified silica surfaces were characterized by fractal dimension analysis from isotherms with some kinds of adsorptives. The fractal dimensions of the two series of modified surfaces were different from each other with an increase in modified ratio. The fractal dimension of the surface modified with t-butyl alcohol (t-modified surface) increased monotonously with butoxy group density. It is thought that the structure of the t-butoxy group is rigid and that the t-butoxy group cannot change its conformation. On the other hand, the variation of the surface fractal dimension value for the surface modified with n-butyl alcohol (n-modified surface), whose structure is flexible, was unique compared with the t-modified surface. Such discrepancy was assumed to be caused by the difference in the structure of the modifier and the assembled state of modifiers between the t- and n-modified surfaces. In order to investigate the variation of surface structure of the surface modified by the butoxy group with an increase in modified ratio, molecular dynamics simulations were performed. By comparing the results of these simulations with experimental results, it has been clarified that the variation in the mobility of the methyl group in the n-butoxy groups was closely related to the change in the surface fractal dimension value for the n-modified surface. It was then elucidated that this mobility change was caused by steric hindrance among the groups. Furthermore, the variation of conformation in the n-butoxy groups, which was obtained from molecular dynamics simulations, was in good agreement with the change in the wettability of the n-modified surface. It is suggested that the surface density of the modifier, the covering structure and the bulkiness significantly influence the wettability of the modified surface. [ABSTRACT FROM AUTHOR]