Component Of Surface Free Energy Research Articles

Adhesion-cohesion balance of prepreg tack in thermoset automated fiber placement. Part 1: Adhesion and surface wetting

The constitution of prepreg tack in automated fiber placement (AFP) is affected by a sensitive balance between adhesive interfacial bond strength and cohesive strength of the prepreg resin. In an effort to explore the role of interfacial liquid-solid interaction on the tack of commercial aerospace-grade epoxy prepreg, a surface wetting analysis was performed on AFP-related substrates. The standard test liquid combination water/diiodmethane and extracted neat epoxy resin were used for contact angle measurement employing the sessile drop method and the Owens-Wendt-Rabel-Kaelble (OWRK) model. Additional rheological and topographical analyses were carried out to account for viscous resin flow on surfaces of different roughness. The results from the material characterization are discussed against the background of tack measurement by probe tack testing utilizing a rheometer. Significant differences between the investigated surfaces in terms of both the maximum tack level and the onset temperatures of adhesion were found as a function of test parameters relevant for contact formation. General agreement with the experimental tack results was observed employing a topographically extended version of the Dahlquist criterion. For each substrate, a temperature-dependent critical storage modulus could be determined that conforms to the onset temperature of tackiness. Contact angle measurements revealed a correlation between the thermodynamic work of adhesion and maximum tack and, moreover, the tack onset in the adhesive regime when additionally incorporating surface topography. Matching ratios of polar and dispersive surface free energy and surface tension components were found to favor the molecular interaction at the interface between prepreg resin and substrate.

Influence of roughness on polar and dispersed components of surface free energy and wettability properties of copper and steel surfaces

The most urgent problems in meso-, micro- and nano-technological productions are controlling wetting of metals and alloys and liquid spreading over engineering surfaces after their hardware abrasive processing. Nowadays, there is a lack in theoretical basis and comprehensive experimental studies to predict the texture formation and change of the functional surface properties (including wetting) of metals and alloys after abrasive processing. In this study, based on the analysis of the three dimensional roughness parameters (amplitude, hybrid and feature) and elemental composition of the near-surface layer, the features of texture formation, changes in the surface free energy and wettability of copper and steel surfaces that are widely used in industry were established after their hardware abrasive processing. The use of abrasive material with an average grit size of up to 100 μm was found to significantly change the surface roughness. The abrasive processing significantly modifies the polar component in the surface free energy, while not influencing its dispersed component. The texture parameters allowing one to control both the growth and decrease of the polar component in the surface free energy were determined. It is shown that the abrasive processing directly influences the wettability properties and allows varying the contact angles in a sufficiently wide range of from 54.0° to 108.2° (for copper surfaces) and from 71.6° to 89.5° (for steel surfaces).

The Influence of Battery Acid on the Destruction of Acrylic Coatings of Car Bodies

Renovation coatings of car bodies undergo destruction under the influence of operational factors. Like ultraviolet radiation, erosion, and aggressive media (among others, battery acid). This article concerns the evaluation of the influence of battery acid on the destruction of acrylic coatings previously non-aged, as well as aged climatically for 2 years. Ageing of the coatings with battery acid contributed to a degradation increase of their chemical structure. It was supported by a considerable increase in the polar component of surface free energy (SFE) of the coatings. In the case of prior climate ageing, the increase in the polar component was even higher. Moreover, the coating’s ability to absorb battery acid increased, which induced blistering. The DSC method revealed that the action of battery acid caused more intense oxidation of coating material, and as a result, the brittleness increased, leading to chipping of the coating surface layers. This led to the increase in surface roughness, measured using an interferometric method. The coatings previously climatically aged for 2 years presented higher values of surface roughness parameters than the non-aged ones. The increase in the surface roughness contributed to a substantial decrease in the gloss of coatings. A sharp difference in colour escalating with the lengthening of the ageing period was also observed using the spectrophotometric method.

Surface free energy and wettability properties of transparent conducting oxide-based films with Ag interlayer

ITO, ZTO, AZO and Ag are commonly used in transparent conducting oxide (TCO)/metal/TCO electrodes to form multilayered thin films on a suitable substrate. A detailed surface free energy (SFE) knowledge of these films is critical to design desirable TCO-based sandwich structures. In this study, TCO/Ag/TCO multilayer thin films were coated onto glass substrates using ITO, ZTO, AZO and Ag targets by magnetron sputtering. The wettability properties of TCO, Ag interlayer and TCO/Ag/TCO were evaluated by contact angle measurements of seven different liquids having various surface tension values. The dispersive and polar components of SFE were calculated using geometric and harmonic mean approaches. The acidic and basic components of SFE were calculated using van Oss-Chaudhury-Good method. Following this, the work of adhesion values between TCO films and Ag interlayer were estimated using SFE values of the films. The results show that the SFE components of the surfaces differ depending on the TCO type, the total SFE values of TCO/Ag/TCO films were lower than that of TCO films, and AZO/Ag adhesion is stronger than the other TCO/Ag structures. The reasons behind these differences were discussed by evaluating the SFE, XRD, AFM and SEM analysis simultaneously.

Effect of Atmospheric-Pressure Plasma Treatments on Fracture Toughness of Carbon Fibers-Reinforced Composites.

In this study, nano-scale fillers are added to epoxy matrix-based carbon fibers-reinforced composites (CFRPs) to improve the mechanical properties of multi-scale composites. Single-walled carbon nanotubes (SWCNTs) used as nano-scale fillers are treated with atmospheric-pressure plasma to introduce oxygen functional groups on the fillers’ surface to increase the surface free energy and polar component, which relates to the mechanical properties of multi-scale composites. In addition, the effect of dispersibility was analyzed through the fracture surfaces of multi-scale composites containing atmospheric-pressure plasma-treated SWCNTs (P-SWCNTs) under high load conditions. The fillers content has an optimum weight percent load at 0.5 wt.% and the fracture toughness (KIC) method is used to demonstrate an improvement in mechanical properties. Here, KIC was calculated by three equations based on different models and we analyzed the correlation between mechanical properties and surface treatment. Compared to the composites of untreated SWCNTs, the KIC value is improved by 23.7%, suggesting improved mechanical properties by introducing selective functional groups through surface control technology to improve interfacial interactions within multi-scale composites.

Effect of ambient plasma treatment on single-walled carbon nanotubes-based epoxy/fabrics for improving fracture toughness and electromagnetic shielding effectiveness

The development of flexible, lightweight, thin, and high-performance electromagnetic interference (EMI) shielding materials is a key challenge for dealing with the issue of increasing susceptibility in modern devices. Recently, agglomeration of carbon nanotubes (CNT) is a critical issue in CNT-based multi-scale composites used as flexible and lightweight EMI material. Herein, a ambient plasma-treatment is applied to increase the interfacial adhesion between single-walled carbon nanotubes (SWNTs) and the epoxy matrix, with control of dispersibility via an increase in the surface free energy and polar components. In spite of a low content of SWNTs, the highly dispersed conductive network thereof provides the prepared multi-scale composites with good conductivity and a high EMI shielding effectiveness (SE) of ~45.2 dB at a thickness of 0.6 mm, along with favorable flexibility and a remarkable fracture toughness (KIC) of ~36.0 MPa.m1/2.

Evidence for intermolecular forces involved in ladybird beetle tarsal setae adhesion

Why can beetles such as the ladybird beetle Coccinella septempunctata walk vertically or upside-down on a smooth glass plane? Intermolecular and/or capillary forces mediated by a secretion fluid on the hairy footpads have commonly been considered the predominant adhesion mechanism. However, the main contribution of physical phenomena to the resulting overall adhesive force has yet to be experimentally proved, because it is difficult to quantitatively analyse the pad secretion which directly affects the adhesion mechanism. We observed beetle secretion fluid by using inverted optical microscopy and cryo-scanning electron microscopy, which showed the fluid secretion layer and revealed that the contact fluid layer between the footpad and substrate was less than 10–20 nm thick, thus indicating the possibility of contribution of intermolecular forces. If intermolecular force is the main physical phenomenon of adhesion, the force will be proportional to the work of adhesion, which can be described by the sum of the square roots of dispersive and polar parts of surface free energy. We measured adhesion forces of ladybird beetle footpads to flat, smooth substrates with known surface free energies. The adhesive force was proportional to the square-root of the dispersive component of the substrate surface free energy and was not affected by the polar component. Therefore, intermolecular forces are the main adhesive component of the overall adhesion force of the ladybird beetle. The footpads adhere more strongly to surfaces with higher dispersive components, such as wax-covered plant leaves found in the natural habitat of ladybird beetles. Based on the present findings, we assume ladybird beetles have developed this improved performance as an adaptation to the variety of plant species in its habitat.

Effect of working gas on physicochemical and biological properties of CaP coatings deposited by RFMS

Thin calcium phosphate (CaP) coatings were deposited on titanium substrates by radio frequency magnetron sputtering of hydroxyapatite target in neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe). The influence of the working gas (Ne, Ar, Kr and Xe) on the wettability and biodegradation in the RPMI 1640 synthetic culture medium of the CaP coatings was investigated. This paper is the first comprehensive study of working gas effect on properties of the CaP coatings. There was an increase in the polar component of surface free energy (SFE) and a decrease in the dispersion component of SFE with an increase in the atomic mass of the working gas. All CaP coatings had a pronounced protective effect, reducing double the number of dead cells in culture compared to the Ti control. The most soluble CaP coatings formed in the atmosphere of Xe stimulated the hAMMSCs division, which led to an increase in the total number of cells (208% of the initial culture). Samples with CaP coatings formed in an inert gas atmosphere increased the gene expression (ALPL, BMP6, BMP2) in vitro . The most biocompatible coatings were those formed in the atmosphere of Xe and Ar.

An Experimental Investigation into the Effect of Asphalt Binder Modified with SBR Polymer on the Moisture Susceptibility of Asphalt Mixtures

There are several experimental methods for improving the moisture strength of asphalt mixtures. Utilization of anti-stripping materials is the most prevalent method. In the present paper, the influence of polymer materials on asphalt binder was investigated using repetitive loading test in wet and dry conditions along with thermodynamic parameters based on the Surface Free Energy components of asphalt binder and aggregates. The results obtained from the present study indicated that using Styrene Butadiene Rubber polymer has improved the asphalt mixtures strength against the moisture damage, especially in the specimens made of granite aggregates. Also, Styrene Butadiene Rubber polymer increased the cohesion free energy and reduced the energy released by the system during the stripping event, which represented a decrease in the tendency for stripping. The stripping percentage index, which is obtained by a combination of the results of the repetitive loading test in wet and dry conditions along with the results of thermodynamic parameters, represented that the specimens made of controlled asphalt binder in the loading cycles under wet conditions had a higher stripping rate. It was also concluded that the modulus loss rate in the control asphalt mixtures was faster than the modified specimens.

Assessing the surface free energy of modified asphalt binder with image processing technique

When the asphalt binder does not comply with the required specification for pavement, the suggested remedy is the implication of modifiers to enhance the quality. In the present investigation, asphalt cement binder was modified with varying percentages of two types of modifiers, Sulfur (3, 5, 7, and 10) % and Carbon Black (5, 10, and 15) % by weight of asphalt cement. The image processing technique was implemented to evaluate the surface free energy components (dynamic and static contact angles) of the treated asphalt cement by implementing the sessile drop and Wilhelmy plate techniques. The aim of this investigation is to assess how the image processing can detect the variation in the adhesive properties through the assessment of surface free energy of the asphalt cement due to the addition of the modifiers. For the comparison process, the surface free energy components of the control asphalt are also determined. Considering the test result obtained, it was concluded that Carbon black is more appropriate additive, it gives an ultimate total surface free energy increment of (7.7 and 6) % as compared with (2.8 and 3.1) % for sulfur when Sessile drop and Wilhelmy plate methods are implemented respectively when compared with the control binder.

Plasma Treatment of Thermally Modified and Unmodified Norway Spruce Wood by Diffuse Coplanar Surface Barrier Discharge

This work deals with the treatment of wood surfaces by diffuse coplanar surface barrier discharge (DCSBD) generated at atmospheric pressure. The effect of the distance of the sample from the electrode surface and the composition of the working gas in the chamber was studied. Norway spruce (Picea abies) wood, both unmodified and thermally modified, was chosen as the investigated material. The change in the surface free energy (SFE) of the wood surface was investigated by contact angles measurements. Chemical and structural changes were studied using infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Activation at a 0.15 mm gap from the electrode led in all cases to an increase in the SFE. The largest change in SFE components was recorded for wood thermally modified to 200 °C. At a 1 mm gap from the electrode increase of SFE occurred only when oxygen (O2) and argon (Ar) were used as working gas. Treatment in air and nitrogen (N2) resulted in an anomalous reduction of SFE. With the growing temperature of thermal modification, this hydrophobization effect became less pronounced. The results point out the importance of precise position control during the DCSBD mediated plasma treatment. A slight reduction of SFE on thermally modified spruce was achieved also by short term ultra-violet (UV) light exposure, generated by DCSBD.

Physicochemical and magnetic properties of functionalized lanthanide oxides with enhanced hydrophobicity

According to the developed bioinspired method in the one-step procedure, the material with the petal effect was switched to lotus one. Therefore, highly hydrophobic and super-hydrophobic materials with tunable adhesive properties and fractal-like structures were successfully produced with high efficiency (67–84%). The work's essence was to modify chemically selected powders of lanthanide oxides (CeO2, Pr6O11, Nd2O3, and Gd2O3). High effectiveness of the functionalization process with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FC6) and n-octyltriethoxysilane (C6) was proven by various techniques, e.g. XPS, HR-TEM, ATR, XRD, zeta potential. Materials with water contact angle between 143.6° (CeO2-C6) and 175.5° (Nd2O3-FC6) with thermally stable nanolayer (up to 380 °C) were generated. Surfaces functionalized with FC6 possessed a polar component of surface free energy (SFE) close to zero. Water behavior in contact with the modified materials was studied, taking into consideration the unique electron structure of lanthanides assessed by goniometric measurement, also adhesion and spreading pressure were determined. Very low adhesion and polar SFE partly resulted in immediate bouncing of water droplet upon contact with the modified surface. The presented method allows preparing stable materials with a high potential in materials chemistry and modulation of surface features and engineering (e.g. heat transfer fluids, specific coating).

Eco-friendly PDLC composites based on chitosan and cholesteryl acetate

A series of five eco-friendly PDLC composite films based on cholesteryl acetate liquid crystal and chitosan were obtained and characterized. The resulted composites were evaluated in terms of structure and morphology by FTIR and RAMAN spectroscopy and scanning electron microscopy, while their thermotropic behavior was evaluated by polarized optical microscopy and differential scanning calorimetry. Moreover, the contact angle and surface free energy components were measured and calculated. All the data revealed that chitosan, through the presence of hydroxyl, amine, and amide groups in its structure, has the ability to constrain the cholesteryl acetate liquid crystal to grow as radial droplets, perturbing its supramolecular chiral ordering. The size of the droplets and their density depended on the mass ratio between the polymer and the liquid crystal almost in all cases, the micrometric droplets having diameter from 5 to 8 μm, sizes which are the most recommended for optoelectronic applications. By changing the mass ratio between the components, PDLC composites with different hydrophobicity were obtained, consequence of both, their chemical composition and their geometrical microstructure of their surface.

Epoxidised natural rubber as adhesion promoter in natural rubber based compounds

Natural rubber (NR) is the most preferred raw material for both tyre and non-tyre applications, which require good adhesion performance. It has a naturally sticky character to provide green tack. However, it has limitations to improve adhesion further due to its relatively low reactivity. In this study, epoxidised natural rubber (ENR) has been evaluated as an adhesion promoter for NR based model tyre compounds. ENR based adhesive compounds were prepared by blending NR with ENR in various ratios. Rheological, physical, and mechanical properties of NR/ENR compounds were studied. Sufficient cure rate and cure extent were achieved for elevated curing temperatures. The adhesion performance was measured with the T-peel adhesion test. In addition, thermodynamic work of adhesion (TWA) was calculated by using the surface free energy components of the compounds. The correlation between adhesion force and TWA was evaluated together with vulcanisation kinetic parameters in order to understand the adhesion mechanism. ENR incorporation was found to improve adhesion between selected tyre compounds, remarkably.

Investigating the impact of zeolite on reducing the effects of changes in runoff acidity and the moisture sensitivity of asphalt mixtures

Most studies evaluating the performance of asphalt mixtures against moisture damage use distilled water or drinking water to create wet conditions. However, the main part of the moisture entering the asphalt layers in the pavement is the rainfall runoff that contains dust, soot, and other pollutants absorbed by the pavement surface, which affect the acidity of rainfall runoff. Accordingly, the impacts of water acidity and Zeolite as an environmental pollutant absorbent, as well as a pH moderator of the water entering the asphalt layers, were investigated on the moisture sensitivity of different asphalt mixtures with mechanical and surface free energy (SFE) tests. The results of the mechanical methods revealed that the change in the runoff acidity increases the moisture damage potential of asphalt mixtures. Asphalt cement modification with Zeolite reduced the drop in the tensile strength ratio (TSR) as a result of changing the pH. The application of Zeolite increased the base component of SFE and reduced the acid component of the asphalt cement. The use of Zeolite caused the formation of amorphous chains in the asphalt cement structure, which increased the nonpolar component of SFE. The polar SFE component of the asphalt cement was slightly improved with the incorporation of Zeolite. The utilization of Zeolite increased the free energy of cohesion, thereby increasing the resistance of the asphalt cement film to cohesive failure. In addition, the debonding energy calculations indicated a decrease in this component due to asphalt cement modification. The results of both mechanical and thermodynamic methods illustrated that asphalt cement modification with Zeolite has a positive effect on decreasing the debonding energy and, thus, reducing moisture damage.

Synthesis of segmented polyurethanes containing different oligo segments: Experimental and computational approach

Incorporation of hydrophilic and hydrophobic agents into a polymer backbone is an effective approach to control its interfacial characteristics. Segmented polyurethanes (PUs) are easy-fabricating and cost-effective candidates in this respect. In this work, we have synthesized polycarbonate (PC)-based PUs containing hydrophilic Polyethylene glycol (PEG) and hydrophobic Polyhedral Oligomeric Silsesquioxane (POSS) in the lab as well as in molecular dynamics simulations. We employed several experimental techniques and a coarse-grained (CG) molecular dynamics (MD) method to evaluate the morphology and microphase arrangement of PUs. We successfully synthesized superior hydrophilic and hydrophobic coatings by replacing some parts of the soft segment (PC) with PEG and the chain extender (1,4-butandiol) with POSS, respectively. Our CG MD simulations showed that POSS is dispersed in PC uniformly, while PEG is completely phase separated from PC and formed a lamellar structure. This was also confirmed by experimental thermal analysis. Eventually, water contact angle (WCA) measurements proved development of very hydrophilic (PU-PEG), slightly hydrophilic (PU), and very hydrophobic (PU-POSS) coatings. The surface free energy analysis indicated that POSS decreases polar and apolar components of surface free energy, while PU-PEG exhibits omniphilic behavior. The presence of PEG and POSS on the surface was also confirmed by contact angle and AFM measurements. According to MTT and LDH assays, PEG and POSS incorporation significantly enhanced the biocompatibility of PU such that PU-PEG and PU-POSS coatings become prospective candidates for biomedical applications.

Investigating the Effect of Metal Nanomaterials on the Moisture Sensitivity Process of Asphalt Mixes

One of the most common damages in asphalt mixes is the destructive effect of moisture on the binder cohesion and binder–aggregate adhesion which is called moisture damage. There are various methods to improve adhesion and reduce moisture damage in asphalt mixes. The most common of them is using an appropriate additive for binder modification. Accordingly, the current research was conducted to investigate the effect of two nanomaterials (Nano CuO, and Nano SnO2) in 2 different percentages on 2 types of aggregates (granite and limestone) and a type of base binder. In order to investigate the effect of nanomaterials, indirect tensile cyclic loading (the same as resilient modulus test) in dry and wet conditions and surface free energy (SFE) method were used. The moisture sensitivity indicator which shows stripping percentage of aggregate surface in loading cycles using SFE results and indirect tensile cyclic loading, has been considered as the moisture sensitivity indicator in this research. Results of mechanical tests used in this research show that nanomaterials have significantly increased asphalt mixes strength in comparison to control specimens. Results obtained from SFE method show that nanomaterials increase the cohesion free energy; this change causes a reduction in the possibility of failure in binder membrane. Additionally, nanoparticles have increased and reduced basic component and acidic component of SFE, respectively. This leads to improvement of their adhesion with acidic aggregates, which is sensitive to moisture damage.

Deposition, morphology and functional properties of layers based on DLC:Si and DLC:N on polyurethane

DLC:Si and DLC:N (diamond-like carbons doped with Si or N) functional layers in different configurations are deposited on polyurethane (PU) for bioengineering applications using CCP (capacitively coupled plasma) discharge generated in the PE CVD (plasma-enhanced chemical vapor deposition) system. Scanning electron microscopy (SEM) observations show that the obtained single and multilayers are continuous and well adherent to the substrates, but they differ in surface morphologies. DLC:Si layers form granular-like outer surfaces, while DLC:N ones a mosaic structure of plain areas. Topography analyses by atomic force microscopy (AFM) and optical profilometry reveal that Si-doped layers are characterized by significantly higher surface roughness (Ra ca. 5 nm) in comparison to N-doped layers (Ra ca. 0.3 nm) and also higher values of profile roughness parameter Rz (up to 32 μm vs. about 13 μm). Energy-dispersive X-ray spectroscopy (EDS) analysis indicates the homogenous chemical composition of the layers. DLC:N layers, are characterized by significantly higher polar component of surface free energy (up to ca. 5.0 mJ/m2). DLC:Si layers exhibit higher values of diiodomethane contact angle (up to ca. 90°) compared with DLC:N layers (up to ca. 55°). The attenuated total reflectance Fourier transform infrared spectroscopic measurements (ATR-FTIR) of the layers reveal that the addition of silicon to the DLC structure increases the content of terminal CHn bonds (n = 1, 2, 3) as well as beneficial Si–H and Si–CHn bonds, which significantly reduce the internal stresses in the layers. Both DLC:Si and DLC:N layers exhibit no cytotoxic effects using the human osteoblast-like cell line and human keratinocytes.

Prediction and pareto-based multi-objective optimization of moisture and fatigue damages of asphalt mixtures modified with nano hydrated lime

Moisture sensitivity can lead to damages due to adhesion and cohesion in asphalt mixtures that cause serious damages to the pavement. Adhesion between bitumen and aggregate is a basic prerequisite for the proper performance of asphalt mixtures. The role of nano hydrated lime (NHL) as an anti-stripping agent has been extensively studied in asphalt pavements. In this study, in addition to investigating the effect of NHL as bitumen modifier on moisture and fatigue damages, and bitumen-aggregate adhesion and bitumen membrane cohesion using surface free energy (SFE) concept, the prediction model to achieve optimal additive percentage with two objectives of moisture sensitivity and fatigue failure by multivariate regression (MVR), group method of data handling (GMDH) and genetic programming (GP) were provided. By the use of the modified non-dominated sorting genetic algorithm II (NSGA-II) approach, Pareto fronts were then plotted. In addition, boiling water testing was applied to examine the sensitivity of mixtures to moisture. To simulate environmental conditions, asphalt mixtures were placed in freeze–thaw (F-T) cycles of 1, 3 and 5. 85–100 penetration grade base bitumen was modified with 0.5%, 1% and 1.5% NHL (by the weight of bitumen). The results indicated that by decreasing the number of yellow pixels in the image processing of modified mixtures with NHL, modification of bitumens decreased the moisture sensitivity of specimens. Using NHL increased the resistance of the specimens to moisture and fatigue damages. The amount of indirect tensile strength (ITS) and fatigue life of asphalt mixtures reduced by rising the number of F-T cycles. The highest increase in ITS and fatigue life was obvious in modified mixtures with 1.5% and 1% NHL, respectively. The results of calculating the surface free energy (SFE) components of the base and modified bitumens showed that using NHL enhanced the total SFE amount of bitumens. Also, using the NHL increased cohesion free energy (CFE), adhesion free energy (AFE) and debonding energy (DE) of modified bitumens and decreased the permeability of asphalt mixtures (PAMs) amount. Among the various methods, the GMDH method had the highest R2. So that the R2 value of GMDH for tensile strength ratio (TSR) and the ratio of fatigue life (NFR) was 93.9% and 86.9%, respectively. The two-objective optimization results indicated that 1.29% NHL was the best optimal amount to maximize the TSR and NFR values simultaneously.

Hydrophobicity and surface free energy to assess spent coffee grounds as soil amendment. Relationships with soil quality

The aim of this work was to evaluate the effects of spent coffee grounds (SCG), a highly hydrophobic raw material, on the hydrophobicity of two Mediterranean agricultural soils. Physical, chemical, mineralogical and biological soil properties, most of them used to evaluate soil quality, were studied and related to the main hydrophobicity parameters. The in vitro assay was performed with two SCG doses (2.5 and 10%), two soils and two incubation times (30 and 60 days). Hydrophobicity was determined by the water drop penetration time test (WDPT), the contact angle (CA) with H2O, formamide and diiodomethane, and the surface free energy components (SFE) calculated using the Van Oss model. The addition of SCG increased the WDPT, CA and SFE, being the latter which was related to a greater number of soil quality variables. Hydrophobicity was related to lower humus quality index (HQI), and a higher proportion of labile organic matter, as shown by Infrared and UV–vis spectroscopy. An increase in hydrophobicity was related to an improvement of soil physical quality: a high aggregate stability index, saturated hydraulic conductivity, porosity (total and macro), water retention, and a less bulk density. The most critical effect related to the increase in hydrophobicity was the significant decrease in the available water content. The SEM images showed a greater occlusion and stabilization mechanism of the SCG particles incorporated in Vega soil, probably due to its higher content of smectite and carbonates. The appearance of fungal biomineralizations of calcium carbonate is associated with SCG addition and could be considered as an interesting and little studied process of inorganic carbon fixation and secuestration. These results showed that hydrophobicity can afford relevant information that can help to asses soil quality status after an amendment with SCG.