Surface Contact Angle Measurements Research Articles

Effect of Organic Cation Adsorption on Ion-Transport Selectivity in a Cation-Permselective Nanopore Membrane.

A key knowledge gap in the emerging field of nanofluidics concerns how the ionic composition and ion-transport properties of a nanoconfined solution differ from those of a contacting bulk solution. We and others have been using potentiometric concentration cells, where a nanopore or nanotube membrane separates salt solutions of differing concentrations to explore this issue. The membranes studied contained a fixed pore/tube wall anionic charge, which ideally would prohibit anions and salt from entering the pore/tube-confined solution. We have been investigating experimental conditions that allow for this ideally permselective cation state to be achieved. Results of potentiometric investigations of a polymeric nanopore membrane (10 ± 2 nm-diameter pores) with anionic charge due to carbonate are presented here. While studies of this type have been reported using alkaline metal and alkaline earth cations, there have been no analogous studies using organic cations. This paper uses a homologous series of tetraalkylammonium ions to address this knowledge gap. The key result is that, in contrast to the inorganic cations, the ideal cation-permselective state could not be obtained under any experimental conditions for the organic cations. We propose that this is because these hydrophobic cations adsorb onto the polymeric pore walls. This makes ideality impossible because each adsorbed alkylammonium must bring a charge-balancing anion, Cl-, with it into the nanopore solution. The alkylammonium adsorption that occurred was confirmed and quantified by using surface contact angle measurements.

A new insight on a novel auxiliary collector 4-MBA synergize with BHA to enhance flotation of scheelite

The hydroxamic acid reagents are extremely pervasive in the collector of scheelite flotation. The high flotation cost is caused by its large dosage and high price. A novel auxiliary collector 4-methodybenzoicacid (4-MBA) was used in combination with benzohydroxamic acid (BHA) to optimize the flotation reagents system for scheelite in the study. A single 4-MBA has weak collection capacity for scheelite. Nevertheless, the combination of 4-MBA and BHA optimized the flotation system of scheelite by ensuring its recovery and reducing the reagent consumption. The results of solution surface tension and contact angle measurements showed that the surface tension of the mixed reagent solution is a relatively lower and the hydrophobicity of the scheelite surface is a relatively higher in the BHA and 4-MBA mixed reagent system. Additionally, a synergistic effect between BHA and 4-MBA on Pb2+ activated scheelite is revealed by the Zeta potential measurements, infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The addition of 4-MBA promoted the physical and chemical adsorption of BHA. The results of molecular dynamics simulation (MDS) further explained that the collector adsorption layer of the surface of scheelite (112) is more compact under BHA and 4-MBA mixed reagent system, which prevents the vertical entry of water phase and improves the hydrophobicity of scheelite. Finally, the bench-scale flotation experiment verified that the addition of 4-MBA enhanced scheelite flotation with BHA, and decrease the flotation cost of scheelite.

Study on effect of magnetization on wetting characteristics of water with different ions to coal dust

Coal dust is a significant problem in underground coal mining, and more economical and effective methods are needed to control coal dust. Magnetized water dust removal technology is considered to be an effective method to solve the problem of high concentration dust. In order to further understand the role of ions in magnetic fields in water, the optimal magnetic field parameters for solutions containing various ions were determined by surface tension and contact angle measurements. The wettability experiments have shown that the optimal magnetization effect can be obtained by placing NaCl solution with the concentration of 0.04 mol/L in the 150mT magnetic field for 120 s at room temperature. Subsequently, the influence of various ions in water on the wettability of coal was investigated using a combination of FTIR testing and Zeta potential experiments. The results showed that the order of the influence intensity of different ions on the wettability of water was Na+ > Mg2+ > Ca2+ when the Cl– content was 0.04 mol/l, and Cl– > CO32– > SO42– when the Na+ content was 0.04 mol/L. Furthermore, Lorentz forces can influence various ions, accelerating their migration and enhancing their accessibility to water clusters. Different ions exert force on the dipoles within water molecules, which can promote or suppress hydrogen bond cleavage. When the number of hydrogen bond breaks rises, it leads to an increase in the wetting properties of the solution. The research findings provide a theoretical foundation for the use of magnetization technology in dust suppression with mist spray in underground coal mines.

Single-Walled (Magnetic) Carbon Nanotubes in a Pectin Matrix in the Design of an Allantoin Delivery System.

Single-walled carbon nanotubes (SWCNTs) outperform other materials due to their high conductivity, large specific surface area, and chemical resistance. They have numerous biomedical applications, including the magnetization of the SWCNT (mSWCNT). The drug loading and release properties of see-through pectin hydrogels doped with SWCNTs and mSWCNTs were evaluated in this study. The active molecule in the hydrogel structure is allantoin, and calcium chloride serves as a cross-linker. In addition to mixing, absorption, and swelling techniques, drug loading into carbon nanotubes was also been studied. To characterize the films, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, surface contact angle measurements, and opacity analysis were carried out. Apart from these, a rheological analysis was also carried out to examine the flow properties of the hydrogels. The study was also expanded to include N-(9-fluorenyl methoxycarbonyl)glycine-coated SWCNTs and mSWCNTs as additives to evaluate the efficiency of the drug-loading approach. Although the CNT additive was used at a 1:1000 weight ratio, it had a significant impact on the hydrogel properties. This effect, which was first observed in the thermal properties, was confirmed in rheological analyses by increasing solution viscosity. Additionally, rheological analysis and drug release profiles show that the type of additive causes a change in the matrix structure. According to TGA findings, even though SWCNTs and mSWCNTs were not coated more than 5%, the coating had a significant effect on drug release control. In addition to all findings, cell viability tests revealed that hydrogels with various additives could be used for visual wound monitoring, hyperthermia treatment, and allantoin release in wound treatment applications.

A novel approach to mixed micelles formation: study the interactions between bis-quaternary ammonium salts and nonionic surfactant Triton X-100

Abstract This article focuses on the description of novel mixed system formulations of bis-quaternary ammonium salts (bis-QASs) and the nonionic surfactant Triton X-100 (TX-100). Measurements of surface tension (γ), foam stability, contact angle (CA) and cloud point (CP) were investigated at different ratios of the given compounds. The results indicated that changes in the structure of the bis-QASs amphiphilic cation, including the length of the alkyl spacer and the presence or absence of –OH groups, affected the adsorption and micellization. Furthermore, the elongation of the alkyl spacer in the bis-QASs structure affects the increase in the CP temperature. The research carried out shows the future potential of mixed combinations (bis-QASs and TX-100) to be used in industrial applications.

Effect of surface topography and wettability on shear bond strength of Y-TZP ceramic

Zirconia ceramics have been widely used as dental restorations due to their esthetic appearance and high flexural strength. The bonding of zirconia with resin cement should rely on both mechanical and chemical bonds. This study was performed to investigate the effect of zirconia surface topography and its wettability after surface pretreatments on the microshear bond strength (μSBS) of a resin cement. Zirconia slabs were prepared and randomly divided into 5 groups based on the surface treatment as follows: no treatment (control), air abrasion (AB), etching with hydrofluoric acid (F), the mixture of hydrofluoric acid and nitric acid (FN), or the mixture of hydrochloric acid and nitric acid (CN) for 10 min. The specimens were subjected to investigation of surface roughness characteristics [average roughness (Ra), peak-to-valley average distance (Rpv), skewness (Rsk), and kurtosis (Rku)] using atomic force microscopy (AFM) and measurements of surface contact angle (θc) and μSBS of a resin cement. In addition, the area % of the nanoscale surface irregularity (nSI%) was calculated from the AFM images. The effects of nSI%, Ra and θc on the μSBS were analyzed by multiple linear regression analysis (p < 0.05). Multiple regression analysis revealed that the nSI% was the most predominant factor for the μSBS (p < 0.001). A surface with larger nSI%, higher Ra and relatively lower θc was essential for establishing a reliable resin-zirconia bond.

Modified hydrophobic and oleophilic polyurethane sponge for oil absorption with MIL-53

A hydrophobic composite sponge (HPCS) is developed for the first time using the dip coating and drying method in an effort to remove organic contaminants like toluene and various oils from water. We employed a polyurethane (PU) sponge, which is reasonably priced, easily accessible, high mechanical strength and a suitable porous substrate on which the hydrophobic composite of MIL-53(Al) along with PDMS was anchored. A crystalline metal organic framework (MOF), MIL-53(Al), with adjustable porosity, functionality, and hydrophobicity is used for oil absorption. Polydimethylsiloxane (PDMS) is utilized to increase the hydrophobicity of MIL-53(Al). The MIL-53(Al)@PDMS composite was used to the produce a sponge having high hydrophobicity and oleophilicity. In contrast to PU sponge, which has a low water contact angle (79.64°), the hydrophobic composite sponge showed a wide range of oil absorption capacity (12–50.5 g/g), a very low amount of water absorption (0.84 g/g), and water contact angle of 128.13°. This hydrophobic composite performed phenomenally by separating out various oils and solvents from water even in varying ionic strengths. Moreover, the recyclability of the formed composite was also performed resulting into 6–20 cycles for different oils and solvents. The synthesized hydrophobic composite sponge was characterized using FT-IR, XRD, TEM, surface area analysis, FESEM, XPS, TG analysis and contact angle measurement. Furthermore, the materials used in the synthesis of composite are non-toxic and do not harm the environment, resulting in no greenhouse gas emissions making our composite environmentally friendly.

Green synthesis of chitin/lignin based-polyurethane composites

Polyurethanes (PU) are still among the most promising high-performance materials in industrial applications. Nevertheless, the development of sustainable and efficient materials is an ongoing challenge for the plastics industry. In recent years there has been growing interest in utilizing natural materials such as chitin and lignin as additives in polyurethane foam production. This study focuses on the utilization of sustainable chitin–lignin filler for polyurethanes with the aim of producing sustainable, cost-effective, and efficient foam materials. A chitin–lignin filler was prepared using a mechanochemical approach, and flexible polyurethane foams (FPUFs) were synthesized with varying amounts of chitin–lignin additive. The resulting foams were characterized using various analytical techniques, including scanning electron microscopy, compression testing, tensile strength analysis, and measurements of surface free energy and contact angle. Possible interactions between the filler and PU were analyzed by means of FTIR spectroscopy. The results show that the addition of chitin–lignin filler improved the mechanical properties (in comparison to pristine chitin and lignin as filler), with a significant reduction in the compression set of the polyurethane foams, a crucial property in the production of seat foams. Synergy was observed between chitin–lignin filler in PU foam. Overall, the study demonstrates the potential of chitin–lignin as a sustainable and efficient natural filler that can be effectively applied on the industrial scale. The combination of these two biopolymers led to a polyurethane composite with better mechanical properties. Additionally, the use of biopolymers (chitin and lignin) as a filler for FPUFs is one of the options for the management of waste materials, which is in line with the idea of sustainable production.

Affordable methods for surface tension and contact angle measurements

In this paper, we present two different experiments aimed at supporting the understanding of surface phenomena at undergraduate level. In the first experiment, we measure the surface tension of several common liquids like water, oil, alcohol, etc by using a simplified custom-built Du Nouy ring apparatus. In the second experiment, the contact angle at the water-glass-air interface is estimated by means of two glass slides that form a sort of variable-size capillary. Materials and experimental apparatuses require a low budget, but the results agree very well with those reported in the literature, obtained with much more sophisticated and expensive equipment. This makes the experiments presented here suitable for educational paths aimed at understanding surface phenomena at undergraduate and even at high school level.

Is Ammonium Hydrogen Difluoride a Solution for Zirconia Surface Conditioning?

This research investigated the topographical features and phase transformation of high-translucent monolithic zirconia after different surface conditioning methods. Zirconia slabs were divided into six groups according to surface treatment method. Group I: etched with hydrofluoric acid (HF); Group II: etched with an experimental acid solution (EAS); Group III: melt-etched with ammonium hydrogen difluoride (AHD); Group IV: air abrasion (AB); Group V: etched with EAS after air abrasion (AB+EAS); Group VI: melt-etched with AHD after air abrasion (AB+AHD). Surface topographies of specimens were documented by scanning electron microscopy (SEM). Tetragonal-to-monoclinic phase transformation was detected by X-ray diffraction and surface evaluation of zirconia specimens; surface roughness and contact angle measurements were performed. The data were statistically analyzed by the Kruskal- Wallis test and post hoc tests (P⟨0.05). The acid-etched zirconia groups (Group I, II, and III) showed the lowest contact angle and surface roughness values (P⟨0.05), while the air abrasion groups (Group IV, V, VI) showed the highest. The SEM images also supported these results. Within the limitations of this in vitro study, treating the monolithic zirconia surfaces with EAS or AHD after air abrasion may be recommended to alter the zirconia surfaces.

Development of Mg-based metal matrix biomedical composites for acicular cruciate ligament fixation by reinforcing with rare earth oxide and hydroxyapatite – A mechanical, corrosion, and microstructural perspective

Abstract This study provides an insight into the synthesis of high-strength and corrosion-inhibiting Mg-based biodegradable implant material by the addition of rare earth oxide material for acicular cruciate ligament reconstruction applications. The matrix has been reinforced with a naturally occurring mineral, hydroxyapatite (Ca5(PO4)3OH) and rare earth oxide, neodymium oxide (Nd2O3), in different concentrations. The mechanical response has been assessed by analyzing the samples’ microhardness, ultimate compressive, and tensile strength. In contrast, the corrosion rates were calculated using phosphate buffer saline solution by using different techniques under suitable physiological conditions. The microstructure characterization has been carried out by field emission scanning electron microscope, electron dispersive spectroscopy, optical microscopy, and X-ray diffraction techniques. Moreover, the surface properties of the composites were assessed using surface roughness and contact angle measurements. The sample showed maximum hardness at a concentration of 1.5% rare earth oxide. Moreover, the highest ultimate compressive and tensile strength followed the same order, i.e., 1.5% &gt; 2% &gt; 1%. In addition, the microstructure analysis revealed a refined microstructure and the formation of secondary intermetallic phases. Resistance to dislocation and grain growth barricading were the prominent features highlighted in the study for enhanced mechanical and corrosion properties. Moreover, the hydrogen evolution was lower for Mg–HA–1.5Nd2O3 samples, which was a clear indication of a reduced corrosion rate.

Theoretical and experimental approaches to the preparation, characterization and application of a newly synthesized mesoporous Zn-MOF as a selective ionophore for Ni(II) ion in carbon paste electrode matrix

A novel carbon paste electrode (CPE) chemically modified with a newly synthesized Zn-metal organic framework (Zn-MOF) was synthesized for Ni(II) ion determination with impressing enhancement in sensitivity and selectivity over the preceding studies. Due to their electrocatalytic and substantial surface area criteria, MOFs are a reasonably new category of fascinating materials for precise electrochemical detection. Under the sonication condition, a novel Zn-MOF depending on a Schiff base ligand in nano size was synthesized, and it was characterized using different characterization methods such as powdered X-ray diffraction (PXRD), FT-IR, BET surface area, contact angle and scanning electron microscope (SEM) combined with energy dispersive X-ray analyzer (EDX). The BET surface area and contact angle measurement techniques results were 2901.08 m2 g−1 and 143.49°, respectively, for the synthesized MOF. It was concluded that under the ideal experimental circumstances, the produced Zn-MOF can extract and sense nickel ions from aqueous solution selectively. Several crucial factors were optimized to gain the ultimate electrochemical response. Response mechanism was proved by the aid of study of morphological change and functional groups chemical shifts. Ultimately, a calibration with a Nernstian slope of 28.75 mV decade−1 over linear concentration limits from 5.0 × 10−8 to 1.0 × 10−1 mol L−1 (R2 = 0.9990) and detection limit of 5.0 × 10−8 mol L−1 was obtained. The relative standard deviations and recovery ranges of the proposed approach for determining the Ni(II) ion in various water and food tests (n = 5) were 0.94–2.35% and 97.0–104%, respectively.

Waste plastic derived reduced graphene oxide as a potential additive for the surfactant polymer flooding: A sustainable solution

The twenty-first century's major problems are the demand for sustainable green energy and the eco-friendly upcycling of plastic waste. The solutions to these problems should have an alluring cost-effective industrial synergy. Tackling these issues address the clean energy generation concerns and the long-term preservation of the economy and environment from plastic waste. This study focuses on upcycling waste plastics into reduced graphene oxide (RGO) and their application in enhanced oil recovery. Raman and TEM analysis confirmed the successful synthesis of RGOs. In addition, FTIR helps study the presence of functional groups and TGA for thermal stability analysis. The RGO improves the oil recovery by altering wettability, reducing surface tension / interfacial tension, and minimizing surfactant loss. The surface / interfacial property and wetting attributes of the RGO-based prepared solution were examined by surface tension and contact angle measurement. The surface tension and contact angle reduction using RGO were ∼25% and ∼20% without surfactant. Whereas with surfactant (anionic, cationic, and nonionic) and RGO, the reduction in surface tension was ∼55%, ∼57%, and ∼57%, respectively. Also, the reduction in contact angle with surfactant was ∼83%, ∼46%, and ∼80% for anionic, cationic, and nonionic surfactant with RGO particles. The chemical slug's viscosity was then examined at elevated temperatures. The viscosity results follow the power law model to comprehend fluid flow behavior. Finally, the chemical slug consisting of a surfactant mixture, RGO particles, and an industrial-grade polymer was used in the sand pack flooding studies recovering ∼71% of the original oil in place.

Insight into selective depression of sodium thioglycallate on arsenopyrite flotation: Adsorption mechanism and constructure

Arsenopyrite is a hazardous substance exist in copper concentrate, thus causing serious environmental pollution during the smelting process. However, the selective depression of arsenopyrite remains a challenge to flotation. This study aims to analyze the depression mechanism of sodium thioglycallate (STG) towards arsenopyrite in the Cu-As separation flotation. Micro-flotation tests confirmed that STG was able to selectively depress arsenopyrite in chalcopyrite flotation and lowered As content in copper concentrate. Local electrochemical impedance spectroscopy (LEIS) demonstrated that STG preferred to adsorb on arsenopyrite than on chalcopyrite, which enhanced electrochemical impedance and reduced surface reactivity. Furthermore, surface adsorption test and contact angle measurement illustrated that STG hindered butyl xanthate (BX) adsorption on arsenopyrite surface, thus the wettability of arsenopyrite was further enhanced. The results of fourier transform infrared spectroscopy (FTIR), DFT caculation and Molecular dynamics simulations (MDS) revealed that STG chemically bond with Fe and As sites on the surface of arsenopyrite through its -SH group, and it formed a hydrogen bond with water molecules via its -COO- group at the top of molecule. Ultimately, a bridge-similar constructure was generated among arsenopyrite, STG and water molecules. This constructure resulted in a stable hydrophilic film covered on arsenopyrite surface, thus its flotability was severely deteriorated.

A comparison of antibacterial activity in dark-UV light in perspective of surface and structural properties of spray pyrolysis grown Cu doped Cr2O3 thin films

Thin films of Cr2O3 and Cu doped Cr2O3 thin films were prepared using the spray pyrolysis technique with different Cu/Cr ratios. Precursor solution of 0.2 M was sprayed on a pre-heated (≈ 400 °C) soda lime glass substrate using air as the carrier gas. XRD analysis confirmed polycrystalline nature of the films with rhombohedral structure. Crystallite size and lattice strain have been estimated using Williamson-Hall method. These films were porous and presented a rough morphology and showed a strong signature on the presence of vibrational Cr-O bonding. The solid-liquid surface contact angle measurements revealed a large contact angle which is indicative of reduced surface energy. Vickers hardness measurement reveals that Cr2O3 thin film with 2% Cu/Cr ratio have high hardness value of 903 HV (0.2 kgf). The antibacterial activity of the films was investigated against two gram-positive (Bacillus Subtilus and Bacillus Meurellus) and two gram-negative bacteria (Escherichia Coli and Acetobacter Rhizopherensis). A comparison was established both under dark and UVA light in terms of structural properties of the films. Antibacterial activity was significantly enhanced with the increase in Cu/Cr ratio. Interestingly, the UVA light further facilitated to boost the antibacterial effect against both types of bacteria. A good correlation was found between the structural parameters and the zone of inhibition.

Characterization of Arboblend V2 Nature Textured Surfaces Obtained by Injection Molding

Surface texturing is an engineering technology used in order to improve the surface characteristic of plastic parts obtained by injection molding. Applying this process not only changes the part surface properties, but also its topography. The novel functionalities of plastic products become useful when other materials make contact with the textured surface. Of course, these characteristics may vary depending on the laser positioning, dimensions, and geometry of the texture. The present paper presents the surface characteristics obtained after the laser texturing of the Arboblend V2 Nature biodegradable polymer. Three distinct geometries were studied: hexagonal, square, and triangular, and different behaviors of them were highlighted during surface free energy (SFE) and contact angle (WCA) measurements: a hydrophobic character for square and hexagonal geometry with distilled water as the measure liquid, and a hydrophilic character with diiodomethane as the measure liquid; for triangle geometry, the contact angle measurements were impossible to extract because the drop turns into a flat puddle. Additionally, the friction coefficient varied depending on the geometry texture, with the lowest value being recorded by the sample with hexagonal geometry. The micro-indentation tests highlighted increased surface micro-hardness compared to the basic material. The possibility of use in the practice of textured surfaces is viable; thus, based on the obtained results, there is even the possibility to replace non-biodegradable polymers from different sectors of activity.

Open Questions that Can Bridge Intermolecular Interactions and Macroscopic Wetting/Dewetting Behaviors of Thin Films

AbstractPolymer films and coatings are ubiquitous in nanoscale applications where confined macromolecules experience greater interfacial effects, causing deviations from bulk material properties; however, the fundamental physics dictating their wetting behavior remains poorly understood. This review provides a perspective on thickness‐dependent surface wettability in thin polymer films characterized by critical thickness, where surface energy and contact angle measurements deviate from bulk values. In contrast with dewetting behaviors, which are well‐modeled by van der Waals (vdW) potentials to afford several nanometers of critical thickness, an unexpectedly large critical thickness of ≈100 nm is reported for thin polystyrene films via surface energy and contact angle measurements. This deviation in the critical thickness highlights an opportunity to modify the current theoretical understanding of the vdW potential model. In addition, possible explanations to interpret the long critical length scales are discussed: 1) challenges in sample preparations and contact angle measurements; 2) temperature dependence of surface energy; and 3) the cooperative nature of polymers. This review invites researchers to bridge the knowledge gap between macroscopic behaviors (e.g., wetting/dewetting) and molecular‐level understanding (e.g., vdW potentials) in polymer thin films.

A dendrite suppression coating formulated via electrophoretic deposition using Bi-functional surfactants for Zn-ion batteries

Aqueous Zn-ion batteries (ZIBs) are promising for large-scale energy storage due to their low cost and high safety. However, ZIBs suffer from Zn dendrite growth and side reactions over the charge-discharge processes. Herein, a facile and scalable strategy was developed based on electrophoretic deposition (EPD) of surfactant-stabilized multi-wall carbon nanotubes (MWCNT) to enhance the reversibility of Zn foil. The MWCNT coating provides high surface area and improved electronic conductivity, thus facilitating rapid charge transfer behavior over the Zn 2+ plating/stripping processes. The results indicated that cationic surfactants, cetyltrimethylammonium bromide (CTAB), are feasible to improve the stability of Zn anode as electrolyte additives in parallel to dispersion and charging of MWCNT. Single-crystalline cryptomelane-type α-MnO 2 nanowires were successfully synthesized by oxalate-reduction of potassium permanganate under ambient conditions. The ZIBs, prepared by α-MnO 2 nanowire cathode and MWCNT coated Zn anode, demonstrated surpassing rate capacity and long cycling stability. The interfacial analysis of electrodes, based on surface tension and contact angle measurements, shed some light on the design and development of multi-functional additives for advanced ZIBs. • A dendrite suppression coating was fabricated by electrophoretic deposition. • Surfactants are found to be electrolyte additives paralleled to CNT deposition. • Single-crystalline α-MnO 2 nanowires were synthesized under ambient conditions. • Interfacial properties were analyzed for wettability and tension measurements.

Cotton waste and nanoclay‐based phenolic novolac epoxy composites and evaluation of their properties

AbstractIn this study, two types of biobased epoxy composites were prepared by using only alkali‐treated cotton waste (CtW), or with the nanoclay (NC) in the form of hybrid reinforcement. Phenol novolac‐type epoxy resin (EPN) was used as a matrix. Untreated (CtW) and alkali‐treated (NaOH‐CtW) particles were characterized by scanning electron microscopy (SEM)/energy‐dispersive X‐ray spectroscopy (EDX). The average size for NC was determined as 3838 nm. Composites were prepared at 10–50 wt% NaOH‐CtW and 20 wt% NaOH‐CtW/(1–2–3–4–5) wt% NC ratios. The morphology of the composites was investigated using SEM. The composites' properties were determined by applying thermogravimetric analysis (TGA), and various tests (tensile, hardness, water sorption, and surface contact angle measurement). The tensile strength of pure EPN was 96.6 MPa, while it changed in the range of 74–98 and 81–106 MPa for NaOH‐CtW and hybrid composites, respectively. All hybrid composites exhibited higher Young's modulus values (7.7–8.9 GPa). Thermal values of hybrid composites were found higher and their char percentages varied in the range of 28.9–30.3%. NaOH‐CtW increased the water sorption of the epoxy matrix from 0.59% up to 6% by 50 wt%. In contrast, a decrease in water sorption of NC composites was observed.

Improvement of the durability of cement-based material through surface modification with nano-engineered releasing agents

• Modified releasing agent with NS/NT to make nano-engineered releasing agent. • NS and NT increased the contact angle of releasing agent and help their adhesion on mold. • Reduction of the surface porosity (within 2 mm thick). • Nano-engineered releasing agent can achieve durable concrete surface. Aggressive substances can gain access to the inner structure of cement-based materials through the surface, resulting in deterioration of the structure. This work developed an effective way of improving the quality of cement-based materials surface by applying nanoSiO 2 -/nanoTiO 2 -engineered releasing agents (nSRa/nTRa) on the formwork surface. Continued with our previous work, the positive effects of nSRa/nTRa on cement hydration were used to improve the surface quality of the cement-based samples through its spraying on the mold surface. This work firstly characterized the adhesive properties of these agents on mold surface (contact angle and viscosity measurement), and then their effects on the surface microstructure and the durability of cement-based materials such as 1) sulfate resistance, 2) chloride resistance, and 3) freeze–thaw resistance were determined. Results showed that nanoparticle addition increased the contact angle of releasing agents and helped their adhesion to mold. Applying nSRa/nTRa on cement-based samples benefited the reduction of surface porosity (within 2 mm thick) by 14.2 %, 19.4 %, 8.6 %, and 18.9 % in the nS2Ra-, nS4Ra-, nT4Ra- and nT16Ra-engineered samples. After 120 days of sulfate attack, mortar samples cast in Ra-, nS4Ra-, and nT16Ra-coated molds showed reductions in compressive strength loss of 1.57 %, 0.73 %, and 0.23 %. Noticeable reductions in the chloride migration coefficient of 23.9 % and 26.6 % were found in the nS4Ra-/nT16Ra-modified mortar sample, while their relative dynamic modulus elasticity was 6.72 % and 12 % higher than Ra-sample after 200 freeze–thaw cycles. This work proved that nano-engineered releasing agents can effectively improve the durability of the concrete structure.