Contact Angle Of Water Droplet Research Articles

3D Xanthium-like of Ni-Co-Zn ternary alloys as superhydrophobic coatings toward porous Ti surface for its anti-icing performances

Super-hydrophobic surface has attracted great interests as functional coatings in spacecraft wings and wind-turbine fans. With the ever-increasing demands of durability and low cost, the scopes for industrial application of hydrophobic coatings have been restricted. Herein we proposed an innovative and simple approach for electroplating Ni0.12Co0.88-xZnx (x = 0–0.36) coatings toward porous Ti substrate. Featuring as 3D Xanthium-like spherical textures, the Ni-Co-Zn ternary alloy coatings were achieved by optimizing the Zn2+ concentration and complexing agent (Na3Cit) in bath. Results validated that its crystal size was refined into ∼300 nm, leading into pinning growth through hole-hole linked porous channel of Ti substrate to increase interfacial strength. Based on the wettability tests, it depicted the water-droplet contact angle (WCA) value of 126.3° attached with sliding angle (SA) of 17.5° for coating samples after being exposed in air for 14 days. Further studies of different ageing treatments on micro structural evolution and super-hydrophobic characteristics were well explored. Through artificial ageing at 200 °C, its attained super-hydrophobic surfaces shorted than 7 days, showing the maximal WCA value up to 153.2° and SA ≤ 7.8° for Ni0.12Co0.88-xZnx (x = 0.24) samples, which was mainly contributed to the self-assembly of multi-tentacles ZnO dendrites. Meanwhile the anti-icing behaviors were compared and featured as peach blossom at −10 °C for all the samples. The icing-delay time of water droplets on coating samples was >1425 s, which was 20 times longer than that of porous Ti substrate. Similarly, it was higher than 90 % for its self-cleaning efficiency based on salt pollutants. Besides the mechanical durability of tested samples against the abrasion-resistant tests and water impact-resistance tests were studied. Results implied that good durability was achieved for Ni-Co-Zn superhydrophobic coatings, but sanded surfaces within a serious decrease of WCA was obtained after a continuous testing for 30 min by abrasion-resistant tests because of the partial destruction of Xanthium-like spherical textures. With the respect to reconstructing of multi-tentacles ZnO dendrites onto the Ni-Co-Zn coatings in air, it was the bio-inspired strategies for self-healing super hydrophobic metal coatings used in warship surfaces, etc.

Experimental and fluid flow simulation studies of laser-electrochemical hybrid manufacturing of micro-nano symbiotic superamphiphobic surfaces.

Micro-nano symbiotic superamphiphobic surfaces can prevent liquids from adhering to metal surfaces and, as a result, improve their corrosion resistance, self-cleaning performance, pollution resistance, and ice resistance. However, the fabrication of stable and controllable micro-nano symbiotic superamphiphobic structures on metal surfaces commonly used in industry remains a significant challenge. In this study, a laser-electrochemical hybrid subtractive-additive manufacturing method was proposed and developed for preparing copper superamphiphobic surfaces. Both experimental and fluid simulation studies were carried out. Utilizing this novel hybrid method, the controllable preparation of superamphiphobic micro-nano symbiotic structures was realized. The experimental results showed that the prepared surfaces had excellent superamphiphobic properties following subsequent modification with low surface energy substances. The contact angles of water droplets and oil droplets on the surface following electrodeposition treatment reached values of 161 ± 4° and 151 ± 4°, respectively, which showed that the prepared surface possessed perfect superamphiphobicity. Both the fabrication method and the test results provided useful insights for the preparation of stable and controllable superamphiphobic structures on metal surfaces in the future.

Fabrication of Micron-Structured Heatable Graphene Hydrophobic Surfaces for Deicing and Anti-Icing by Laser Direct Writing

As a novel method to prepare graphene, the laser-induced graphene (LIG) technology has numerous outstanding properties and has been widely applied in various fields. Nevertheless, the challenge remains to easily and efficiently prepare multifunctional surfaces of graphene through laser microregulation and fine structure design. Here, we successfully fabricated a micron-structure gully graphene surface with hydrophobicity and electrothermal functionality under atmospheric conditions using a 10.6 μm CO2 laser to directly write on the surface of a polyimide film (PI). The impact of the laser scanning speed on the surface morphology and chemical composition of the product was investigated by analyzing the SEM (scanning electron microscope) observations and Raman spectra, respectively. The mechanical stability of the surface was studied by analyzing the contact angle of water droplets on the surface after mechanical circulation and the delayed icing effect after repeated icing. The deicing and anti-icing performance of the surface were analyzed based on its resistance to surface icing and electric deicing time. According to the experimental results, we first observed a linear negative correlation between the generated structure linewidth and the laser scanning speed. Additionally, we successfully achieved one-step preparation of primitive continuous graphene structures with a superhydrophobic capability (151°). Furthermore, our findings indicate that micron-structured graphene surfaces exhibit excellent mechanical stability, effectively delay icing formation, and demonstrate efficient electric deicing effects. These results demonstrate the potential application of CO2 laser-induced graphene technology in the field of surface preparation for deicing and anti-icing. This work offers a novel one-step approach for the fabrication of micron-structured heatable graphene surfaces with simultaneous superhydrophobicity, deicing, and anti-icing functionalities on polymer substrates.

Soft wetting: Modified Cassie-Baxter equation for soft superhydrophobic surfaces

The classic Cassie-Baxter equation has been used for decades to describe the equilibrium contact angle of a droplet on a partially wetted, rough substrate and inspired numerous follow-up explorations in wetting. However, the Cassie-Baxter equation itself and its various modified forms apply mainly to rigid surfaces, where the distortion of structures under the surface tension force has not been considered. Encouraged by the trend that many natural surfaces and various modern devices are flexible, here, we study how flexibility of surface structures affects the surface wettability, namely, the equilibrium contact angle of a water droplet. Substrates decorated with soft pillar arrays are fabricated and the equilibrium contact angles of water droplets are measured by substrate vibration. We found a deviation between the measured equilibrium contact angles and those predicted by the classic Cassie-Baxter equation, and the deviation is more pronounced for softer pillars. By incorporating the elastic energy in the deflected pillars along the droplet perimeter into the droplet-structure interfacial system, we develop a modified Cassie-Baxter equation for droplets on soft pillar arrays.

Graphene composite self-healing antifog/frost-resist transparent coatings with zwitter-wettability

Self-healing materials achieve both durability and simplified maintenance by restoring their structure and function. However, self-healing materials utilizing surface hydrophilicity are considered incompatible with zwitter-wettability properties. Therefore, further investigation is needed to fabricate antifogging coatings that combine zwitter-wettability and self-healing properties. In this study, we demonstrated that polymer multilayer graphene composite coatings exhibit simultaneous antifogging and self-healing properties. We achieved a uniform dispersion of an aqueous solution of graphene by directly dispersing in a strong acid polymer and a uniform dispersion of graphene in the membrane via layer-by-layer self-assembly without any post-treatment, enabling precise control of hydrophobicity and water absorption of the membrane. The fabricated layer-by-layer coatings exhibited zwitter-wettability and self-healing performances comparable to those of previously reported systems. The maximum water droplet contact angle on the surface was 99° The 20-bilayer coating also exhibited excellent self-healing performance, closing 100 μm scratches within approximately 60 s and flattening the surface within approximately 300 s of exposure to water. In the antifogging tests, the coatings demonstrated high resistance to harsh cooling environments and exhibited excellent antifogging performance. This study provides a new zwitter-wetting strategy that combines self-healing and antifogging properties, providing an exceptional option for the development of next-generation surface coatings.

Bioconsolidation of Damaged Construction Calcarenites and Evaluation of the Improvement in Their Petrophysical and Mechanical Properties.

Bioconsolidation treatment using bacterial carbonatogenesis has been proposed as an environmentally friendly strategy for the efficient preservation of damaged stones, particularly suitable for carbonate stones. The study presented here deals with the evaluation of the performance of this treatment, applied to damaged carbonate stones in two historical buildings in Spain. The methodology applied in this research serves as a reference for future similar studies. Results showed significant improvement in the petrophysical and mechanical properties of the damaged stone following the treatment through the production of calcite and vaterite by the abundant carbonatogenic bacteria inhabiting the stone. These bacteria were able to effectively consolidate weathered areas if an adequate nutritional solution was employed, thereby augmenting the stone's resistance, as evidenced by the Drilling Resistance Measurement System (DRMS). FESEM images showed calcified bacteria and calcified exopolymeric substances (EPS) consolidating stone minerals without blocking their pores. In addition to consolidation, this biotreatment improves the stone's behavior against water absorption and increases the contact angle of water droplets without significant modifications in the pore size or diminishing vapor permeability. No color changes are observed. Overall, these results show that the application of the nutritional solution (M-3P) for in situ consolidation of different types of porous carbonate building stones is a highly effective conservation method, with no modification of the chemical composition of the treated materials.

Enhancing the hydrophobicity of cement-based materials by fabricating microstructured surfaces: Experimental and numerical study

In cold and humid regions, deterioration and failure of concrete structures are usually closely related to the entry of external water. Increasing attention is being paid to hydrophobic surfaces to reduce the entry of external water and thus improve the durability of concrete structures. In this manuscript, the effect of microstructure on the surface hydrophobicity of hydrophobic rubberized concrete was investigated by wettability tests, and the optimal microstructure morphology that can further improve the surface hydrophobicity was derived. In addition, the multiple-relaxation-time lattice Boltzmann method was used to investigate the wettability of microstructured surfaces of hydrophobic rubberized concrete, and the effect of different microstructures on the contact angle of water droplets on concrete surface was investigated by numerical simulations. The predicted results obtained from the numerical simulations were compared with the analytical and experimental results to verify the accuracy of the numerical models.1.

Fabrication of biomimetic anisotropic crescent-shaped microstructured surfaces by laser shock imprinting

Abstract The crescent-shaped microstructure bionic to the slip zone of the slippery zone of the carnivorous plant genus Nepenthes was fabricated on the surface of copper foil by laser shock imprinting (LSI). The microstructure of crescent-shaped grooves was initially fabricated on the surface of the micro-mold by etching, and then the microstructure was replicated on the surface of copper foil through plastic deformation under laser shock loading. Increasing the laser shock energy or the number of shocks can increase the degree of replication of the crescent-shaped microstructure, the height of the crescent-shaped microstructure, and the contact angle of water droplets on the surface. The wettability of the surface of the crescent microstructure is anisotropic and increases with an increase in offset distance. The anisotropy of the crescent-shaped microstructure causes the solid–liquid contact line in the direction of the bottom of the arc to become a long and approximately straight line. According to the rule that controlling LSI processing parameters can fabricate surfaces with different heights and wettability, a gradient wetting surface consisting of crescent-shaped microstructures was designed to achieve the directional spreading of droplets. By altering the distribution of crescent-shaped microstructures, a type-I flow channel with the ability to limit the spreading range of water droplets was fabricated.

Antibiofouling Slippery Liquid Impregnated Pulsed Plasma Poly(styrene) Surfaces

AbstractBiofouling is a major global environmental and economic challenge wherein organisms settle on solid surfaces submerged in natural waters. This leads to the spread of invasive marine species around the globe, accelerates surface deterioration through microbially‐induced corrosion, and inflates maritime vessel fuel consumption which leads to greater greenhouse gas emissions. In this study, pulsed plasma poly(styrene) nanocoatings impregnated with eco‐friendly liquids are produced that yield slippery surfaces through aromatic–aliphatic intermolecular interactions (water droplet contact angle hysteresis and sliding angle values ≈1–2°). The antibiofouling performance of these slippery surfaces is demonstrated using laboratory‐based marine bioassays and real‐world field trials in freshwater (pond water) and seawater (ocean) environments. Low‐cost and substrate‐independent pulsed plasmachemical deposition combined with eco‐friendly liquid impregnation provides a sustainable approach to tackling environmental biofouling.

Microtopographic superhydrophobic polymer surface to prevent urinary tract infections causing nosocomial drug-resistant bacterial adhesion

Catheter-associated urinary tract infections (CAUTIs) are one of the most prevalent forms of healthcare-associated infections worldwide. Recurrent episodes of infections and development of antibiotic resistance/tolerance among biofilm-forming bacteria are well documented. We developed a simple method of making superhydrophobic micro-structured antibacterial polymer surfaces for coating-free catheters. A two-step fabrication approach was used to turn the hydrophobic polydimethylsiloxane (PDMS) into superhydrophobic surfaces. The nanosecond pulsed Nd:YAG laser was used to fabricate two types of structures (holes and grooves) on a steel mold. The soft-molding technique was adopted to replicate these structures on PDMS films. The pillar structured PDMS surface exhibited a water droplet contact angle (WDCA) of 169○ ± 3° with a low sliding angle of 12○, whereas the grooved surface had 142○ ± 5° contact angle. Moreover, the Luria Broth which is media for bacterial growth shows contact angle of 141○ ± 2° and 120○ ± 3°, respectively. Theoretically, the micro-pillar structures with selected dimensions could sustain the Cassie–Baxter state. The crystal violet binding assay was used to assess the anti-biofilm activity of structured surfaces (grooved and pillared) against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), as well as clinical isolates of Klebsiella pneumonia (K. pneumoniae), E. coli, and S. aureus. Furthermore, the attachment and interaction of bacteria with surfaces were investigated through filed emission scanning electronic microscope (FE-SEM) and confocal microscopy. Overall, the pillar-structured surface reduces the average bacterial attachment more efficiently than a grooved surface (>80% vs. >50% reduction) compared to a plain PDMS surface due to its higher water-repellent property. This work will give new insights into the development of coating-free, long-lasting antibacterial surfaces for polymeric medical devices.

The Glaze Icing Performance of a Robust Superhydrophobic Film Composed of Epoxy Resin and Polydimethylsiloxane

Ice accretion on transmission lines can cause operational difficulties and disastrous events. In this study, a micro/nano-structured epoxy resin/polydimethylsiloxane (EP/PDMS) film on glass, with water droplet contact angles (CA) observed as high as 160° and the water droplet sliding angle (SA) < 1° was fabricated by aerosol-assisted chemical vapor deposition (AACVD). The glaze icing performance of the superhydrophobic EP/PDMS films have been investigated by comparing the bare glass and room temperature vulcanized (RTV) silicon rubber-coated glass substrate representing the glass insulators and silicone rubber insulators, respectively. Compared with the bare glass and the RTV silicon rubber coating, the EP/PDMS superhydrophobic coating showed excellent performance in delaying glaze icing, especially in the early stages of icing. After 20 min of glaze icing with tilting angle of 90° at −5 and −10 °C, 38.9% and 85.7% of the RTV silicon rubber coating were covered, respectively, and less than 3% of the EP/PDMS coating was covered by ice when the blank glass sheet was completely covered. The EP/PDMS films also showed good mechanical robustness and long-term stability, which are important considerations in their widespread real-world adoption.

Effects of bendable P3CT polymers layer on the photovoltaic performance of perovskite solar cells

We report on the formation of bendable and edge-on poly[3-(4-carboxybutyl)thiophene-2,5-diyl] (P3CT) polymers thin layer used as a hole modification layer (HML) in the inverted perovskite solar cell. The aggregations of 2D layer-like P3CT polymers in dimethylformamide (DMF) solution can be formed via aromatic π–π stacking interactions and/or hydrogen-bonding interactions with the different concentration from 0.01 to 0.02 wt%, which highly influences the photovoltaic performance of the inverted perovskite solar cells. The atomic-force microscopic images and water droplet contact angle images show that the P3CT polymers modify the surface properties of the transparent conductive substrate and thereby dominating the formation of perovskite crystalline thin films, which play important roles in the highly efficient and stable perovskite solar cells. It is noted that the V OC (J SC) of the encapsulated solar cells values are maintained to be higher than 1.115 V (22 mA cm−2) after 104 d when an optimized π–π stacked and hydrogen-bonded P3CT polymer is used as the HML. On the other hand, the solar cell showed a high long-term stability by maintaining 85% of the initial power conversion efficiency in the ambient air for 103 d.

Stable Superhydrophobic and Antimicrobial ZnO/Polytetrafluoroethylene Films via Radio Frequency (RF) Magnetron Sputtering.

In this study, superhydrophobic ZnO/Polytetrafluoroethylene (ZnO/PTFE) films with water droplet contact angles (CA) observed as high as 165° and water droplet sliding angles of (SA) <1° have been prepared on glass substrates by RF magnetron sputtering. The PTFE was wrapped on a nano-rod made of a ZnO film with superhydrophobic properties while providing excellent UV resistance compared to hexadecyltrimethoxysilane (HDTMS) hydrophobic agents. The upper surface of the rough ZnO film was coated with PTFE, and most of the underlying coating was bare ZnO, which could well make contact with bacteria. For the Gram-negative strain, E. coli, the cell viability count of the ZnO/PTFE sample (3.5 log reduction, 99.96%) was conspicuously lower than that of the ZnO/HDTMS sample (1.2 log reduction, 93.87%) under 1 h illumination of UV light, which showed that the ZnO/PTFE sample has a better photocatalytic property than the ZnO/ HDTMS films. The ZnO/PTFE films also showed good mechanical robustness, which is an important consideration in their widespread real-world adoption.

Fire-resistant and hydrophobic paper based on Si3N4@PDMS core-shell nanowires with 3D interlocking structure

Paper with simultaneous fire-resistance and hydrophobicity have greatly potential applications in the fields of packing, storage and delivering information, which attracts increasing attention recently. Different from the traditional cellulose-based paper which is extremely easily damaged by water and fire, a new type of highly flexible, fire-resistant and hydrophobic paper based on Si3N4 nanowires and polydimethylsiloxane (PDMS) is reported. Specially, the Si3N4@PDMS core-shell nanowires with 3D interlocking structure are designed, in which the Si3N4 nanowires act as the inorganic fire-resistant frameworks and the PDMS shell with low surface energy provides the hydrophobic surface. The Si3N4@PDMS core-shell nanowires are intertwined and interlaced to form a highly flexible Si3N4@PDMS paper. The tensile strength of Si3N4@PDMS paper is 6.19 MPa, indicating the good mechanical property. The obtained Si3N4@PDMS paper has the characteristics of writability, fire-resistance and hydrophobicity. The high thermal stability of Si3N4 nanowires makes Si3N4@PDMS paper exhibit excellent fire resistance. No obvious change is observed for the commercial paper with Si3N4@PDMS paper as the fire-shielding layer after heating for 30 min. In addition, the contact angles of water droplets are all greater than 110° over the surfaces of Si3N4@PDMS paper after mechanical damages, chemical corrosions and thermal treatments. Si3N4@PDMS paper can be used in oil/water separation and oil collection. More importantly, Si3N4@PDMS paper can be used for writing without being damaged by fire or water. The present work may inspire the development and application of functional paper and is expected to become a breakthrough in the traditional paper industry.

Preparation of Polymer Nanopillar Arrays with Controlled Tip Shapes and Their Application to Hydrophobic and Oleophobic Surfaces.

Ordered arrays of nanopillars with controlled tip shapes were fabricated by a template formation process using anodic porous alumina with controlled pore shapes. Although various studies have been reported on the preparation of nanopillar arrays using anodic porous alumina as a template, there have been no reports on the formation of nanopillar arrays with precisely controlled tip shapes. Re-anodization of anodized samples in a neutral electrolyte can flatten the bottom of pores. The use of the resulting anodic porous alumina as a template enabled the fabrication of ordered nanopillar arrays with a flattened tip. The formation of overhanging nanopillar arrays was also possible by using anodic porous alumina with a controlled pore shape as a template, which was fabricated by a combination of anodization, TiO2 coating by atomic layer deposition, and pore-widening treatment. The contact angles of water and oil droplets were measured using the obtained polymer nanopillar arrays with controlled tip shapes. The contact angle of water droplets did not change regardless of the tip shape of the nanopillars, whereas the contact angle of oil droplets changed depending on the tip shape of the nanopillars. This indicates that liquids with high surface tension are not affected by the nanopillar tip shape, whereas liquids with low surface tension are greatly affected by the nanopillar tip shape. Among the nanopillar arrays fabricated in this study, it was confirmed that the overhanging nanopillar array with many edge structures that have the pinning effect of suppressing the wetting spread of the solution exhibited the highest oil repellency. The method reported here can be used to fabricate nanopillar arrays with a precisely controlled tip geometry, and it is expected that optimization of the geometry will further improve the water- and oil-repellent properties.

Hydrophobicity and FTIR absorbance spectroscopy of Polydimethylsiloxane (PDMS) films treated with aqueous gold nanoparticles (AuNP) solution

Polydimethylsiloxane (PDMS) thin films were treated with aqueous solutions of gold nanoparticles. Samples treated for 24, 48, and 72 h, including untreated PDMS film, were subjected to hydrophobicity test and FTIR absorbance spectroscopy. Hydrophobicity test involved measuring the contact angle of water droplets placed on top of the sample films. Contact angles were measured using Image J software. Treated samples showed significant hydrophobicity changes shown by the increasing value of measured contact angle from 71.3° for the untreated sample to 104.0° for the sample treated for 72 h. FTIR absorbance spectra of the treated sample showed peaks at 3374 cm−1, 3295 cm−1, 2096 cm−1 and 2031 cm−1 with the peak intensity values increasing with corresponding samples of increasing hours of treatment. With the presence of gold nanoparticles on the PDMS film confirmed, the gold nanoparticles may now be functionalized for biosensing and biotesting applications of liquid samples.

Study on Hydrophobic Surface of Magnesium Alloy Prepared by Femtosecond Laser and its Corrosion Resistance

Due to their excellent barrier and shielding effects, superhydrophobic magnesium alloy surfaces are increasingly interested in corrosion protection. This paper proposes a method for producing a stable superhydrophobic surface by laser scanning ablation of AZ31B magnesium alloy on its surface. The prepared layered micro-nanoemulsion convex structure with a lotus-like surface exhibited excellent superhydrophobicity after modification by stearic acid, and the static water droplet contact angle reached 163°. After 90 days in outdoor air, droplet pressure-based experiments show that the superhydrophobic surface possesses a long-term stable Cassie state. In addition, The superhydrophobic surface showed excellent corrosion resistance against magnesium alloy in a Neutral 3.5 wt.% NaCl solution. The results of the dynamic potential polarization tests showed that the existence of a gas layer cavity on the lotus-like surface structure caused the corrosion current density of superhydrophobic AZ31B (3.86±1 uA/cm2) to decrease by 2 orders of magnitude compared with that of the extruded AZ31B (103±1 uA/cm2). We believe the proposed method is simple, efficient, and non-polluting, especially for medical magnesium alloys in the field of in vivo implant materials to slow down corrosion and promote clinical applications.

Synthesis, characterization and investigation of hydrophobic and self-cleaning properties of modified Zn–Mn and Cu–Mn nano spinels

Nano spinels of zinc-manganite and copper-manganite were synthesized by the co-precipitation method. Characterization of synthesized nanoparticles has been carried out using X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV–vis diffuse reflectance spectroscopy (DRS), Field emission scanning electron microscopy (FESEM) and Atomic force microscopy (AFM) methods resulting in confirmation of the target phase formation performance of synthesized nanoparticles evaluated in photodegradation methyl red organic dye. In addition, synthesized nanoparticles were coated on sand-blasted glass and modified using palmitic acid to reach the hydrophobic surface. The contact angles of water droplets were measured for both surfaces which were 159° and 152° for zinc-manganite and copper manganite, respectively. The hydrophobicity of both coatings was available after 360 days making them a good candidate for the production of hydrophobic coating with photocatalytic activity in a blend with cement-like materials.

Microstructural and micromechanical modeling of gum-gelatin-based soft tissue engineering scaffolds

Oral and dental diseases, including periodontal disease, are among the most common conditions in the field of dentistry. The best treatment for this complication is the use of different polymers and multi-component biological tissue prepared through the freeze-drying technique. In this study, biocompatible and biodegradable polymers, namely polyvinyl alcohol (PVA) and gelatin (GN), were used for this purpose, along with Arabian gum-hydroxyapatite (HA) for its antibacterial properties. Arabian gum, with weight percentages of 0, 2, 4, and 6 wt%, was added to the polyvinyl alcohol-gelatin composition at −55 °C for 28 h in the freezer and 48 h at −45 °C under a pressure of 0.01 mbar. The resulting porous biological tissue, with four different ratios, was tested for mechanical and biological analysis in a physiological solution. Then, the samples were analyzed using a scanning electron microscope (SEM) and X-ray diffraction (XRD) technique to study the morphology and structure of the compounds before and after placement in biological solutions. Additionally, a wettability and antibacterial test were performed on the nanocomposite specimen. The SEM observations reveal that this method can create a porous structure with a porosity of about 30–50 μm with a spherical and circular architecture, which was further improved by the addition of gum, reducing the percentage of porosity and improving the tissue's tensile strength and elastic modulus. The porosity changes showed a decrease from 72 % to 60 %, and the tensile strength increased from 53.5 kPa to 76 kPa, resulting in an elastic modulus of 510 kPa to 800 kPa. The addition of gum also reduced the rate of destruction of the biological tissue, making it more suitable for soft tissue applications. The obtained results of the pH test showed that the concentration changes were neutral. The contact angle of water droplets was measured to determine hydrophilicity, indicating an improvement in hydrophilicity after the addition of gum. The results showed that the use of PVA and gelatin, due to their ductility and suitable mechanical properties, along with Arabian gum-HA, could accelerate the healing process of dental periodontal problems.

Energetic and Structural Characterizations of the PET–Water Interface as a Key Step in Understanding Its Depolymerization

We report molecular simulations of the interaction between poly(ethylene terephthalate) (PET) surfaces and water molecules with a short-term goal to better evaluate the different energy contributions governing the enzymatic degradation of amorphous PET. After checking that the glass transition temperature, density, entanglement mass, and mechanical properties of an amorphous PET are well reproduced by our molecular model, we extend the study to the extraction of a monomer from the bulk surface in different environments, i.e., water, vacuum, dodecane, and ethylene glycol. We complete this energetic characterization by the calculation of the work of adhesion of PET surfaces with water and dodecane molecules and by the determination of the contact angle of water droplets. These calculations are compared with experiments and should help us to better understand the enzymatic degradation of PET from both the thermodynamic and molecular viewpoints.