Water Contact Angle Values Research Articles

Facile and effectual surface modification of polyacrylonitrile (PAN)-based ultrafiltration membranes via manipulating the synergistic interaction of dopamine and enzymes

A drastic improvement in the overall permeability and antifouling performance was observed for the polyacrylonitrile (PAN) ultrafiltration (UF) membrane by the co-incorporation of dopamine (DA), protease (E1), and lipase (E2) in a facile multi-step synthetic scheme. SEM was utilized to indicate the successful formation of modifying layers on the membrane surface, whereas ATR-FTIR and zeta potential were used to provide deeper insight into the membrane surface chemistry. AFM and contact angle were used to assess the membrane's surface roughness and hydrophilicity, respectively. The optimally modified membrane surface was found to be quite hydrophilic, as indicated by the water contact angle value (39.8 ± 0.8°), and water flux across the membrane of 78.09 ± 1.6 kg/m2·h. Simultaneously, natural organic matter (NOM), including milk powder (MP), bovine serum albumin (BSA), and humic acid (HA), were efficiently removed, resulting in 99.9, 92.5, and 80.5 % removal efficiencies, respectively. Notably, the enzyme-immobilized membrane demonstrated outstanding antifouling performance as well as long-term stability. The dynamic anti-NOM fouling studies indicated that the surface modification was potentially capable of overcoming the tradeoff between membrane permeability and selectivity, resulting in FRR values of >90 %. The antibacterial properties of the surface-modified membranes against E. coli and S. aureus were also explored, and the optimal enzyme-immobilized membrane was found to be substantially antibacterial. Overall, this study aims to pave the way for the development of sustainable chemistry in designing innovative and highly efficient membranes.

Physicochemical properties of poly (vinylidene fluoride) membrane grafted poly hydroxyethyl acrylates using radiation-induced graft admicellar polymerization

Admicellar polymerization of hydroxyethyl acrylate onto PVDF membranes was investigated using electron beam irradiation to initiate the grafting in order to modify its inheritant physical and chemical properties. The absorbed dose and the monomer concentration controlled the amount of poly hydroxyethyl acrylate (polyHEA) grafted. The grafting degree increased from 8.35 wt% to 27.6 wt% for monomer concentration of 0.5 M and from 21.8 wt% to 48.1 wt% for monomer concentration of 1.0 M, at absorbed dose of 10–50 kGy. The TGA thermogram showed an increase in the DTG degradation peak that occurs within the range 468.35 °C–481.71 °C as the degree of grafting due to the polyHEA on the PVDF surface. Meanwhile, the surface roughness decreased from 94.97 nm for unmodified PVDF to range of 32.86 nm–65.45 nm for the grafted membrane due to the microstructure of polyHEA grafted on the membrane filled the hill and valley in the PVDF membrane. Furthermore, the PVDF membranes with polyHEA demonstrated a lower water contact angle value (45.9°–60.6°) than the unmodified PVDF membranes (75.8°). Hence, radiation-induced admicellar polymerization is a technique that can be utilised as one of the approaches to modify the surface of any membrane.

Cassava Starch Films Containing Quinoa Starch Nanocrystals: Physical and Surface Properties.

Quinoa starch nanocrystals (QSNCs), obtained by acid hydrolysis, were used as a reinforcing filler in cassava starch films. The influence of QSNC concentrations (0, 2.5, 5.0, 7.5 and 10%, w/w) on the film's physical and surface properties was investigated. QSNCs exhibited conical and parallelepiped shapes. An increase of the QSNC concentration, from 0 to 5%, improved the film's tensile strength from 6.5 to 16.5 MPa, but at 7.5%, it decreased to 11.85 MPa. Adequate exfoliation of QSNCs in the starch matrix also decreased the water vapor permeability (~17%) up to a 5% concentration. At 5.0% and 7.5% concentrations, the films increased in roughness, water contact angle, and opacity, whereas the brightness decreased. Furthermore, at these concentrations, the film's hydrophilic nature changed (water contact angle values of >65°). The SNC addition increased the film opacity without causing major changes in color. Other film properties, such as thickness, moisture content and solubility, were not affected by the QSNC concentration. The DSC (differential scanning calorimetry) results indicated that greater QSNC concentrations increased the second glass transition temperature (related to the biopolymer-rich phase) and the melting enthalpy. However, the film's thermal stability was not altered by the QSNC addition. These findings contribute to overcoming the starch-based films' limitations through the development of nanocomposite materials for future food packaging applications.

Nano coloration and functionalization of cellulose drive through in-situ synthesis of cross-linkable Cu2O nano-cubes: A green synthesis route for sustainable clothing system

The textile and clothing industry is under great stress and subjected to the huge utilization of toxic dyes. Metal oxide nanoparticles are getting great attention in textiles as a promising alternative to toxic dyes and organic pigments with added functionality. Unfortunately, the utilization of toxic precursors in the synthesis of nanoparticles and their poor bonding interaction with the textile still offers an open challenge for nano-coloration. The lack of bonding interaction not only leads to the release of nanoparticles in common laundering but also vanishes the functional properties. Herein, we demonstrated a robust, and sustainable process for one-step coloration and functionalization of cotton fabric through an in-situ synthesis of cross-linkable functional Cu2O nanocubes. The nano-cubes to fabric interaction was established through FTIR spectroscopy, while the proposed chemical mechanism provides the theoretical conjecture in support of interaction. The as-prepared nano-dyed fabric presented an attractive yellowish-orange color with excellent dyeing fastness, and wash durability along with the retained hydrophilicity with a water contact angle (WCA) value of as low as 59°. Additionally, the eminence of the development was validated by mapping the processing traits with UN sustainable development goals (SDGs) as a blueprint for easy commercial adaptation. With added functionality of easy-care, antimicrobial and photocatalytic performance while maintaining comfort and color aesthetic (in the absolute absence of toxic reagents) such a process can find tremendous utilization in sustainable clothing needs.

Post-Polymerization Modification of Fluoropolymers via UV Irradiation in the Presence of a Photoacid Generator.

Fluorinated polymers have unique wettability and protein adsorption properties. The site-specific alteration of these properties could expand their application to different research areas. In this work, a fluorinated homopolymer and two of its copolymers with 4-vinylbenzyl glycidyl ether (VBGE) are synthesized by free radical polymerization. The produced polymers are then used to develop resist formulations by the addition of a photoacid generator. Films of these formulations are exposed to ultraviolet radiation through a binary mask and heated to create the pattern. It is found that the water contact angle values of the exposed films areas are reduced compared to those of the unexposed ones, with the exception of pentafluorophenyl methacrylate (PFMA) homopolymer film. This is attributed to the reaction of the epoxy groups creating x-links and producing hydroxyl groups and the cleavage of the pentafluorophenyl group from the ester group leading to carboxylic acid groups. Both modifications on the exposed areas are verified by FTIR spectroscopy and ToF-SIMS analysis. In addition, the biomolecules adsorption ability of the exposed area is increasing 10-15 times compared to the unexposed one for the PFMA homopolymer and the PFMA/VBGE 1:1 copolymer. Thus, the proposed polymers and patterning procedure could find application to spatially directed immobilization of biomolecules and/or cells onto a surface for both biosensing and tissue engineering purposes.

Investigation of grafting silane coupling agents on superhydrophobicity of carbonyl iron/SiO2 particles for efficient oil/water mixture and emulsion separation

The present study demonstrated the wettability properties of grafting silane coupling agents on carbonyl iron (CI)/SiO2 particles for efficient oil/water mixture and emulsion separation. CI particles were first reacted with Tetraethoxysilane (TEOS) to create a magnetic component. Then, CI/SiO2 particles were altered by 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS) and Hexamethyldisilazane (HDMS) to create magnetic superhydrophobic/superoleophilic, recyclable, and reusable sorbent powders. The water contact angle (WCA) values of the as-prepared particles, CI, CI/SiO2, CI/SiO2@FAS, and CI/SiO2@HMDS, were 5.4° ± 1.3°, 6.4° ± 1.4°, 151.9° ± 2.1°, and 170.1° ± 1.1°, respectively. In addition, the oil contact angles (OCAs) of a variety of oils were found to be equivalent to 0°. Hence, superhydrophobic/superoleophilic particles for kind of different oils were shown sorption capacities of 1.7–3.1 g/g and 2.5–4.3 g/g for CI/SiO2@FAS, and CI/SiO2@HMDS, respectively. Besides, for 1%w/w hexane/water emulsion separation efficiency higher than 99%, the lowest mass was obtained at 50 and 200 mg for CI/SiO2@HDMS and CI/SiO2@HDMS, respectively, suggesting a new effective material for separating tiny oil droplets. Also, the reusability and chemical durability of the superhydrophobic samples made them a prime candidate for use in different harsh conditions.

Incorporation of oxidized debranched starch/chitosan nanoparticles for enhanced hydrophobicity of corn starch films

Starch films have superior advantages owing to the renewability and low cost of starch; however, their strong inherent hydrophilic character greatly limits their practical application. This study aimed to improve the hydrophobicity of corn starch films by adding a new type of covalently formed, oxidized debranched starch/chitosan nanoparticles (SC-NPs). SC-NPs were obtained by a Schiff-base crosslinking reaction between the aldehyde group of dialdehyde debranched starch and the amino group of chitosan. Corn starch films reinforced with SC-NPs were obtained using a casting method. A mass ratio of dialdehyde debranched starch and chitosan of 3–5 yielded mainly spherical nanoparticles ranging from 50 to 150 nm in diameter determined by transmission electron microscopy. The water contact angle (WCA) of the pure starch film was only 19.4°, whereas the WCA values of the films reinforced with 3 % SC-NPs were greater than 70°, indicating that SC-NPs efficiently improved the hydrophobicity of corn starch films. The ultraviolet and visible light barrier property of starch films with 3 % SC-NPs were significantly enhanced in comparison with pure starch film. The water vapor permeability, water solubility, and swelling ratio were markedly lower in films with 3 % SC-NPs than in neat starch films.

Fabrication and performance of nickel-based composite mold inserts for micro-injection molding

During the demolding stage of micro-injection molding (μIM), reducing the interfacial interactions (mainly adhesion and friction forces) between the contact interfaces is the key to achieve non-destructive molding of polymer micro/nano structures. In this study, Ni-based composite mold inserts using polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS2) and tungsten disulfide (WS2) with low surface energy and low friction coefficients were fabricated by electroforming. Different nanoparticles could be uniformly distributed in the composite mold inserts without agglomeration at low concentrations, and the orientation of nickel crystal was found to be unchanged by phase composition analysis. The surface energy and adhesion of the inserts could be effectively reduced after the addition of nanoparticles. The molecular dynamics simulation results showed that the value of water contact angle could be closer to the experimental value by adding a surface roughness factor. Due to the self-lubricating property of nanoparticles, the friction coefficient was reduced from 0.75 for pure Ni to 0.25 for WS2 with a concentration of 0.2 g/L. The use of the composite mold inserts with low surface energy and low friction coefficient would solve the problem of microstructure deformation in the demolding stage of injection molded polymer microfluidic chips.

Construction of superhydrophobic graphene-based coating on steel substrate and its ultraviolet durability and corrosion resistance properties

For the first time, a facile and environmentally friendly approach for producing high-quality graphene from the biomass of banana leaves is described in this paper. Two rough coats of Ni-graphene, Ni@G, and Ni-graphene doped with chromium, Ni@Cr-G, were created on steel substrates by electrostatic deposition. These coatings were then submerged in an ethanolic solution of myristic acid, MA, to produce a superhydrophobic, SHP, surface. The Raman spectra demonstrated that the generated graphene was of high quality. Fourier transform infrared spectroscopy findings confirm the modification of the Ni@G coating by MA, Ni@G@MA, and the modification of the Ni@Cr-G composite with MA, Ni@Cr-G@MA. The results of the scanning electron microscope revealed that the created SHP coatings have nanoscale features. The wettability results showed that the water contact angle values for Ni@G@MA and Ni@Cr-G@MA coatings are 158° and 168°, while the water sliding angle values for both coatings are 4.0 o and 1.0°, respectively. The atomic force microscopy results show that both Ni@G and Ni@Cr-G coatings increase the roughness of the steel. The chemical and mechanical stability of the Ni@Cr-G@MA coating was higher than those of the Ni@G@MA coating. The coated steel by Ni@Cr-G@MA exhibits UV stability up to 110 h, while the SHP-coated steel by Ni@G@MA exhibits UV stability for 60 h. The potentiodynamic polarization results show that the value of the corrosion current density for bare steel is 13 times that of steel coated with Ni@G@MA, and 21 times that of coated steel with Ni@Cr-G@MA. The electrochemical impedance spectroscopy, EIS, results show that the charge transfer resistance for steel coated with Ni@G@MA is 38 times that of bare steel, while steel coated with Ni@Cr-G@MA is 57 times that of bare steel. Potentiodynamic polarization and EIS results show that the SHP Ni@Cr-G@MA film exhibits higher corrosion resistance than Ni@G@MA film.

Fabrication and Characterization of Piezoelectric Polymer Composites and Cytocompatibility with Mesenchymal Stem Cells.

Piezoelectric materials are promising for biomedical applications because they can provide mechanical or electrical stimulations via converse or direct piezoelectric effects. The stimulations have been proven to be beneficial for cell proliferation and tissue regeneration. Recent reports showed that doping different contents of reduced graphene oxide (rGO) or polyaniline (PANi) into biodegradable polyhydroxybutyrate (PHB) enhanced their piezoelectric response, showing potential for biomedical applications. In this study, we aim to determine the correlation between physiochemical properties and the in vitro cell response to the PHB-based composite scaffolds with rGO or PANi. Specifically, we characterized the surface morphology, wetting behavior, electrochemical impedance, and piezoelectric properties of the composites and controls. The addition of rGO and PANi resulted in decreased fiber diameters and hydrophobicity of PHB. The increased surface energy of PHB after doping nanofillers led to a reduced water contact angle (WCA) from 101.84 ± 2.18° (for PHB) to 88.43 ± 0.83° after the addition of 3 wt % PANi, whereas doping 1 wt % rGO decreased the WCA value to 92.56 ± 2.43°. Meanwhile, doping 0.2 wt % rGO into PHB improved the piezoelectric properties compared to the PHB control and other composites. Adding up to 1 wt % rGO or 3 wt % PANi nanofillers in PHB did not affect the adhesion densities of bone marrow-derived mesenchymal stem cells (BMSCs) on the scaffolds. The aspect ratios of attached BMSCs on the composite scaffolds increased compared to the PHB control. The study indicated that the PHB-based composites are promising for potential applications such as regenerative medicine, tissue stimulation, and bio-sensing, which should be further studied.

Optimization of electro‐blown polysulfone nanofiber mats for air filtration applications

AbstractDurable, robust, and hydrophobic air filtration media was produced via electro‐blow spinning (EBS) technique using polysulfone (PSU) due to its superior properties. To our knowledge, this is the first optimization study of PSU nanofiber production via EBS technique for air filtration applications. Concentration, air pressure, and voltage were determined as independent variables for the optimization based on “smaller is the better” approach of Taguchi Design of Experiment. The optimized values which supplied the smallest average fiber diameter (AFD) possible were obtained as 13 wt% PSU, 3 bar, and 7.5 kV. The AFD of the sample obtained from the confirmation experiment was calculated as 105 ± 34 nm. Surface morphologies, porosity values, and wettability behaviors of the samples were investigated by using scanning electron microscopy, gravimetric method, and water contact angle measurements, respectively. PSU nanofiber mats exhibited superhydrophobic behavior (water contact angle values up to 159.8°) which is important for various separation processes. Samples prepared at different deposition times (15, 30, 45, and 60 min) were investigated in terms of particle capture efficiency and pressure drop. The 0.3 μm particle filtration efficiency was found to be 98.09% at an expense of 202 Pa pressure drop which would be suitable for various respiratory and HVAC filter applications.

Surface free energy and roughness of flowable dental composites

Purpose The surface properties like roughness, wettability and surface free energy are important for utility properties of traditional and flowable dental restorative composites, due to their role in plaque formation, discoloration, mechanical wear or adhesion and bonding. The goal of our work was to assess the surface free energy (SFE) and the surface roughness (Ra) of three commercial flowable dental composites: everX Flow (bulk), everX Flow (dentin) and Flow-Art. Methods Surface roughness, contact angle and surface free energy were determined for tested composites. Two surface states (control and roughened) were compared. Roughness was measured with the use of the 3D optical profilometer. The contact angle (CA) was determined through the sessile drop method with the use of four different probing liquids. This enabled to apply two surface free energy approaches (Owens–Wendt (O-W) and van Oss–Chaudhury–Good (LWAB)). Additionally, Zisman’s approach (γC) was used. Results The water contact angle values were similar for Flow-Art (67.56±1.49°) and everX Flow (bulk) (68.94±2.72°) compared to higher value for everX Flow (dentin) (74.39±2.05°). SFE was in the range from 43 to 50 mJ/m^2 for O-W and from 47 to 62 mJ/m2 for LWAB. The γC was from 37 to 45 mJ/m^2. Conclusions Roughening composites’ surface influenced on increasing the CA value. All approaches of surface free energy calculations provide useful data for predicting interactions between flowable composites and dental tissues. Tested composites showed good wetting for initial state of surface after polymerization. These influence on better adhesion of the material to the bonding system during dental restoration.

Synthesis and characterisation of cycloaliphatic and aromatic amines based cardanol benzoxazines: A comparative study

In the current study, an attempt has been made to synthesize cardanol-based mono, bi, and tetra-functional benzoxazines by reacting various aryl amines and cycloaliphatic amines with cardanol (C) in the presence of paraformaldehyde under suitable experimental conditions by Mannich condensation. The resultant benzoxazines were characterized using several analytical techniques for their molecular structure, curing behavior, thermal stability, and hydrophobic nature. By using FTIR and 1H-NMR spectroscopic methods, the structure of benzoxazines was ascertained and assessed with benzoxazines based on aryl and cycloaliphatic amines. Using the DSC technique, the curing temperature of benzoxazines was investigated. Tetra-functional benzoxazines have a lower curing temperature than that of other mono- and bi-functional benzoxazines from the various systems of benzoxazines studied. It was also observed that the curing temperature of cycloaliphatic amine-based benzoxazines is also lower than that of aryl amine-based benzoxazines. The low temperature cure behavior of cycloaliphatic amine benzoxazine systems is due to the presence of a tertiary amine group, which contributes to a more basic nature than that of aryl amines. Thermal stability of polybenzoxazines was studied by TGA technique, among the different benzoxazine systems, the poly(C-ap-ddm) has higher char yield (30%) at 850 °C than that of other polybenzoxazines (poly(C-cha), poly(C-a), poly(C-mbch), poly(C-ddm), poly(C-ap-ipda), poly(C-ap-xyda) and poly(C-ap-mbch)). The value of water contact angle of cycloaliphatic amine-based benzoxazineswas found to be higher than that of aryl amines. Among the polybenzoxazines studied, poly(C-ap-mbch) possesses a higher value of water contact angle of 143°. Poly(C-aP-mbch) filled with 10 wt% SBA-15 (Santa Barbara Amorphous-15) possesses a value of lower dielectric constant (1.62) than that of poly(C-aP-ddm) (1.65). Data from different studies, cardanol based tetra functional benzoxazines can be used as sealants, encapsulants, adhesives, and matrices for microelectronics and automotive applications.

Enhancement of water barrier and antimicrobial properties of chitosan/gelatin films by hydrophobic deep eutectic solvent

Biodegradable chitosan/gelatin (CS/GEL) films have attracted attention as food packaging, but the poor water sensitivity and functional limitations of these films should be addressed. In this study, the hydrophobic deep eutectic solvent (DES, 0–15 %) consisting of thymol and octanoic acid was used to improve the water resistance and antibacterial performance of the CS/GEL composite films. FTIR and SEM analyses revealed a strong interaction between the CS/GEL matrix and DES. The films blended with DES showed increased water contact angle values and thermal stability. Furthermore, the addition of DES resulted in a significant increase in the elasticity and decrease water vapor transmission rate (WVTR). The CS/GEL films blended with 9% DES showed a 38.5% decrease in WVTR compared to those without DES. Additionally, the DES-containing film displayed good antibacterial activity against Staphylococcus aureus and Escherichia coli. Overall, the CS/GEL-DES composite films are expected to contribute an improvement to food packaging.

Post-processing of DLP-printed denture base polymer: Impact of a protective coating on the surface characteristics, flexural properties, cytotoxicity, and microbial adhesion.

To investigate the effect of a protective coating on the surface characteristics, flexural properties, cytotoxicity, and microbial adhesion of vat-photopolymerization additive-manufacturing denture base polymers. The specimens were additively manufactured using digital light processing (DLP). Specimen surfaces were coated with the same printed resin, and mechanical polishing was used for comparison. Surface topography, arithmetical mean height (Sa), and water contact angle values were measured. Furthermore, flexural strength (FS)/modulus and fractography were evaluated. Also, cytotoxicity was evaluated by an extract test. Finally, an adhesion test was used to investigate the adhesion of mixed oral bacteria to the specimens. The Sa values in the polished (0.26±0.08µm) and coated (0.38±0.14µm) groups were significantly lower than in the untreated (2.21±0.42µm) and control (2.01±0.37µm) groups. The coating treatment resulted in a higher FS compared to the untreated surface (p=0.0002). After the coating treatment, no significant differences were found in relative cell viability between the groups (p>0.05). The quantitative results showed significantly higher bacterial adhesion in the untreated group than in the polished (p=0.0047) and coated (p<0.0001) groups. The surface characteristics and flexural properties were optimized by the protective coating. Also, the protective coating did not adversely affect cytocompatibility. Moreover, the coating treatment could effectively decrease oral bacteria adhering to the surfaces. Therefore, the protective coating treatment can be a less time-consuming alternative to mechanical polishing as a post-processing procedure for the digital denture.

Improved corrosion resistance of EP coating on Mg alloy through GO hybridization and silica-based superhydrophobic surface

Epoxy resin (EP) coating has high hydrophilicity and poor long-term corrosion resistance. In order to improve its protection ability, an EP-graphene oxide (GO)/SiO 2 multifunctional coating is fabricated on Mg-Zn-Ca alloy in this study, through a spin/spray assisted self-assembly technique. The morphologies and microstructures of the coated samples were observed using scanning electron microscopy (SEM), Fourier infrared spectrometer (FTIR) and atomic force microscope (AFM). Hydrophobicity and self-cleaning property of the composite coating were tested by an optical contact angle meter and black graphite powders. The stability of the superhydrophobic surface was tested by rubbing with sandpaper and immersing in corrosion solution. The corrosion resistance of coated samples was tested in 3.5 % NaCl solution using electrochemical impedance spectroscopy (EIS). The GO sheets are uniformly dispersed in EP coating. EP-GO acts as a dense bottom layer, effectively promoting its adhesion with the superhydrophobic SiO 2 coating, and the water contact angle (WCA) values range from 158° to 168°. After stability testing, the WCA value of the superhydrophobic coating remains at a high level (115°–155°). The R ct of this composite coating was remarkably increased to 1.0 × 10 22 Ω/cm 2 , implying that the corrosion resistance was improved by eighteen orders of magnitude compared to bare substrate. These results show that the combination of the labyrinth effect and the hydrophobic surface extend the corrosion path and reduce the contact area of the corrosion solution with the coating, which strengthens the barrier effect of the composite coating. The composite coating exhibits superior corrosion resistance durability and self-cleaning property. • EP-GO/SiO 2 coating exhibits superior anticorrosion/self-cleaning properties. • Labyrinth and superhydrophobic effects improve the barrier ability. • Superhydrophobic top layer possesses good stability.

Nature-inspired trapped air cushion surfaces for environmentally sustainable antibiofouling

Feathers of seabirds and waterfowl (for example the mallard duck (Anas platyrhynchos)) consist of hierarchical fibrillar structures encapsulated with hydrophobic preen oil. These characteristics afford waterproofing through the entrapment of air pockets, enabling swimming and diving for such bird species. This liquid repellency mechanism for bird feathers is mimicked by surface hydrophobisation of fibrous nonwoven polypropylene textiles to create large volumes of trapped air at the solid–liquid interface (plastron). Higher static water contact angle values correlate to a greater resistance towards water ingress (akin to the behaviour of mallard feathers). In order to extend the trapped gas layer lifetimes, the transportation of air from the water surface to a submerged air bubble by the diving bell spider (Argyroneta aquatica) for respiration is mimicked via short duration (< 1 s) solar-powered air bubble bursts once every 2 h. This combination of ornithological and arachnological inspired approaches yields stable trapped gas layers at the solid–liquid interface which are shown to inhibit biofouling in real-world outdoor wet environments.

Different Radial Modification Profiles Observed on APPJ-Treated Polypropylene Surfaces according to the Distance between Plasma Outlet and Target.

The plasma jet transfer technique relies on a conductive wire at floating potential, which, upon entering in contact with a primary discharge, is capable of igniting a small plasma plume at the distal end of a long flexible plastic tube. In this work, two different long tube configurations were employed for the surface modification of polypropylene (PP) samples using argon as the working gas. One of the jet configurations has a thin copper (Cu) wire, which was installed inside the long tube. In the other configuration, the floating electrode is a metallic mesh placed between two plastic tubes in a coaxial arrangement. In the first case, the tip of the Cu wire is in direct contact with the working gas at the plasma outlet, whereas, in the second, the inner plastic tube provides an additional dielectric barrier that prevents the conductor from being in contact with the gas. Water contact angle (WCA) measurements on treated PP samples revealed that different surface modification radial profiles are formed when the distance (d) between the plasma outlet and target is changed. Moreover, it was found that the highest WCA reduction does not always occur at the point where the plasma impinges the surface of the material, especially when the d value is small. Through X-ray photoelectron spectroscopy (XPS) analysis, it was confirmed that the WCA values are directly linked to the oxygen-functional groups formed on the PP surfaces after the plasma treatment. An analysis of the WCA measurements along the surface, as well as their temporal evolution, together with the XPS data, suggest that, when the treatment is performed at small d values, the plasma jet removes some functional groups at the point where the plasma hits the surface, thus leading to peculiar WCA profiles.

Adsorption of Oil by 3-(Triethoxysilyl) Propyl Isocyanate-Modified Cellulose Nanocrystals

Oil leaks into water bodies and increased organic pollutants harm the environment and ecosystem in several ways, and cleaning up oil spills from water bodies is a global challenge. This research aimed to construct modified cellulose nanocrystal (CNC) based aerogels with 3-triethoxysilyl propyl isocyanate (TEPIC) to evaluate their potential application in oil adsorption. Here, a freeze-drying method was employed to make CNC aerogels. The aerogels were characterized using scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, porosity and density measurements, Fourier transform infrared spectroscopy (FTIR), water contact angle (WCA) measurement, compressive strength, and oil adsorption capacity. SEM results confirmed that the aerogels have a largely porous structure, including a community of uniformly interconnected cellulose fibers. Moreover, the studied aerogels had a low density due to the high porosity. Also, the small pore diameter and high specific surface area were confirmed by the BET evaluation. FTIR confirmed the existence of functional groups and strong hydrogen bonding between CNC/TEPCI/Urea molecules. All TEPIC-modified CNC aerogels had water contact angle values greater than 130° indicating their hydrophobicity. The highest oil and glycerol adsorption was obtained with the use of modified CNC aerogels. Thus, the sample modified with 3 wt% TEPIC showed the highest adsorption capacities of 130 ± 7.22, 120 ± 4.75, and 95.28 ± 4.82 gg−1 for motor oil, vegetable oil and glycerol, respectively. The results of this study showed that ultra-light, hydrophobic and oil adsorbent materials based on chemically modified CNC aerogels can successfully be fabricated.

Production of Superhydrophobic Cotton Fabric by Layer-By-Layer Deposition of SiO2/TiO2-Polydimethylsiloxane

ABSTRACT In this study, the aim was to produce superhydrophobic cotton fabric by TiO2 and SiO2 nanoparticles, and polydimethylsiloxane using layer-by-layer deposition method. It was found that the increase in the bilayer number and PDMS concentration improved superhydrophobicity. In this way, water contact angle values higher than 150° were provided. The scanning electron microscopy and atomic force microscopy analyses demonstrated the formation of surface roughness. Moreover, the physical fabric tests and water and stain repellency tests were also carried out. L-b-L deposited samples were found to be softer and had high water and stain repellency values. The durability of the coatings to washing was also confirmed.