Surface Water Wettability Research Articles

Exploring novel organocatalytic-acetylated pea starch blends in the development of hot-pressed bioplastics

Acetylated starch shows enhanced thermal stability and moisture resistance, but its compatibilization with other more hydrophilic polysaccharides remains poor or unknown. In this study, the feasibility of thermomechanically compounding organocatalytically acetylated pea starch (APS), produced at two different degrees of substitution with alkanoyl groups (DSacyl, 0.39 and 1.00), with native pea starch (NPS), high (HMP) and low methoxyl (LMP) citrus pectin, and sugar beet pectin (SBP, a naturally acetylated pectin) for developing hot-pressed bioplastics was studied. Generally, APS decreased hydrogen bonding (ATR-FTIR) and crystallinity (XRD) of NPS films at different levels, depending on its DSacyl. The poor compatibility between APS and NPS or HMP was confirmed by ATR-FTIR imaging. Contrariwise, APS with DSacyl 1 was effectively thermomechanically mixed with the acetylated SBP matrix, maintaining homogeneous distribution within it (ATR-FTIR imaging). APS (any DSacyl) significantly increased the visible/UV light opacity of NPS-based films and decreased their water vapor transmission rate (WVTR, by ca. 11 %) and surface water wettability (by ca. 3 times). In comparison to NPS-APS films, pectin-APS showed higher visible/UV light absorption, tensile strength (ca.2.9–4.4 vs ca.2.4 MPa), and Young's modulus (ca.96–116 vs ca.60–70 MPa), with SBP-APS presenting significantly lower water wettability than the rest of the films.

Improving the Blood Compatibility and the Gas Permeability of Polyether Ether Ketone Hollow Fiber Membrane Used for Membrane Oxygenator via Grafting Hydrophilic Components

As the core component of extracorporeal membrane oxygenation (ECMO) therapy for patients with severe cardiopulmonary failure, the structures and the properties of membrane oxygenator play a crucial role in determining both the efficiency of the gas exchange and the safety of the patients. Herein, with the aim of enhancing the blood compatibility, gas permeability, and durability of the membrane oxygenator, a porous polyether ether ketone hollow fiber membrane (PEEK-HFM) was prepared via a combination of melt spinning and thermally induced phase separation method. Subsequently, three different hydrophilic components including a nonionic polymer (poly(ethylene glycol), PEG), an ionic monomer (acrylic acid, AA), and a zwitterionic monomer (2-methacryloyloxyethyl phosphorylcholine, MPC) were introduced onto the PEEK-HFM surface by UV-induced grafting. The effects of different hydrophilic modifications on the surface characteristics (such as surface water wettability, surface potential, and porous morphologies) and the related properties (including mechanical performance, blood compatibility, and gas exchange permeability) were studied in detail. After grafting different hydrophilic components, not only the pore size of the corresponding PEEK-HFMs decreased compared to the unmodified PEEK-HFMs but also the surface roughness. Meanwhile, although the hydrophilic modifications resulted in the deterioration of the tensile strength of resulting PHFMs, it enhanced the blood compatibility of modified PEEK-HFMs. Moreover, among these modified membranes, the one grafted with MPC showed the best blood compatibility due to its more hydrophilic surface. Additionally, the modified membranes still maintained excellent gas permeability, ensuring the gas exchange performance between carbon dioxide and oxygen. Furthermore, a comprehensive comparison between the modified PEEK-HFMs and a commercial membrane oxygenator (poly(4-methyl-1-pentene), PMP) demonstrated that the modified PEEK-HFMs exhibited higher gas permeability, better blood compatibility, stronger gas exchange ability, and comparable tensile strength, indicating their potential as a high-efficiency option for membrane oxygenators.

Thiol-ene conjugation of VEGF peptide to electrospun scaffolds as potential application for angiogenesis.

Vascular endothelial growth factor (VEGF) plays a vital role in promoting attachment and proliferation of endothelial cells, and induces angiogenesis. In recent years, much research has been conducted on functionalization of tissue engineering scaffolds with VEGF or VEGF-mimetic peptide to promote angiogenesis. However, most chemical reactions are nonspecific and require organic solvents, which can compromise control over functionalization and alter peptide/protein activity. An attractive alternative is the fabrication of functionalizable electrospun fibers, which can overcome these hurdles. In this study, we used thiol-ene chemistry for the conjugation of a VEGF-mimetic peptide to the surface of poly (ε-caprolactone) (PCL) fibrous scaffolds with varying amounts of a functional PCL-diacrylate (PCL-DA) polymer. 30% PCL-DA was selected due to homogeneous fiber morphology. A VEGF-mimetic peptide was then immobilized on PCL-DA fibrous scaffolds by a light-initiated thiol-ene reaction. 7-Mercapto-4-methylcoumarin, RGD-FITC peptide and VEGF-TAMRA mimetic peptide were used to validate the thiol-ene reaction with fibrous scaffolds. Tensile strength and elastic modulus of 30% PCL-DA fibrous scaffolds were significantly increased after the reaction. Conjugation of 30% PCL-DA fibrous scaffolds with VEGF peptide increased the surface water wettability of the scaffolds. Patterned structures could be obtained after using a photomask on the fibrous film. Moreover, in vitro studies indicated that scaffolds functionalized with the VEGF-mimetic peptide were able to induce phosphorylation of VEGF receptor and enhanced HUVECs survival, proliferation and adhesion. A chick chorioallantoic membrane (CAM) assay further indicated that the VEGF peptide functionalized scaffolds are able to promote angiogenesis in vivo. These results show that scaffold functionalization can be controlled via a simple polymer mixing approach, and that the functionalized VEGF peptide-scaffolds have potential for vascular tissue regeneration.

Effects and Mechanism of Surface Water Wettability and Operating Frequency on Response Linearity of Flexible IDE Capacitive Humidity Sensor.

Flexible capacitive humidity sensors are promising for low-cost, wearable, and radio frequency identification sensors, but their nonlinear response is an important issue for practical applications. Herein, the linearity of humidity response was controlled by surface water wettability and operating frequency of sensor, and the mechanism was explained in detail by surface water condensation. For a sensor with a Ag interdigitated electrode (IDE) on a poly(ethylene terephthalate) substrate, the capacitance showed a small linear increase with humidity up to 70% RH but a large nonlinear increase in the higher range. The response linearity was increased by a hydrophobic surface treatment of self-assembled monolayer coating while it was decreased by an ultraviolet/ozone irradiation for hydrophilicity. It was also increased by increasing the frequency in the range of 1–100 kHz, more prominently on a more hydrophilic surface. Based on experiment and simulation, the increase in sensor capacitance was greatly dependent on the geometric pattern (e.g., size, number, and contact angle) and electrical permittivity of surface water droplets. A larger and more nonlinear humidity response resulted from a larger increase in the number of droplets with a smaller contact angle on a sensor surface with higher water wettability and also from a higher permittivity of water at a lower frequency.

How electrostatic and non-electrostatic interactions play a role in water wettability of possible nanostructure surfaces

The present paper investigated the effects of the electrostatic and non-electrostatic interactions on the water wettability of a surface. Based on this aim, examinations are performed on the molybdenum disulfide (MoS2) as possible nanostructure surface. The results obtained through calculating the water contact angle on the MoS2 surface indicate which this surface is a weak hydrophobic substrate. The present simulations illustrate that the electrostatic interactions have little impact on the wettability amount of the MoS2 substrate. However, the molybdenum disulfide is composed of two charged parts with significant values. In addition, it is observed that the relation between density, van der Waals and electrostatic interactions is different from each other. It have been observed that the van der Waals interactions have direct relationship with water density while there is not anything between the electrostatic interactions and water density peak. The Obtained results via simulation demonstrate that the effectiveness of electrostatic interactions on the wettability depends on the sigma in the Lennard–Jones equation. In the other words, the role of electrostatic and van der Waals interactions on the wettability are not indissociable from each other and this method is sufficient in nanostructure systems.Graphic abstract

Counterion-Tunable Thermosensitivity of Strong Polyelectrolyte Brushes.

In this work, poly(sodium styrene sulfonate) brushes have been employed as a precursor to prepare thermosensitive strong polyelectrolyte brushes (SPBs) through a counterion exchange strategy. The substitution of hydrophilic Na+ counterions by hydrophobic tetraalkylphosphonium counterions leads to a thermoresponsivity of the SPBs. The thermosensitive properties including hydration, stiffness, and surface water wettability of the SPBs can be modulated by the type of the tetraalkylphosphonium counterions. Nevertheless, the wet thickness of the SPBs with tetraalkylphosphonium counterions does not exhibit an obvious temperature dependency due to the high steric barrier in the crowded environment of SPBs generated by the large tetraalkylphosphonium counterions. The mixtures of small Na+ counterions and large tetraalkylphosphonium counterions are employed to realize the thermosensitive wet thickness without sacrificing other thermoresponsive properties of the SPBs because the mixed counterions can bring both a certain hydrophobicity and some free space to the brushes. This work opens up the opportunities available for the use of counterions to tune the thermosensitivity of SPBs.

2D-3D Mixed Organic-Inorganic Perovskite Layers for Solar Cells with Enhanced Efficiency and Stability Induced by n-Propylammonium Iodide Additives.

Device instability has become an obstacle for the industrial application of organic-inorganic metal halide perovskite solar cells that has already demonstrated over 23% laboratory power conversion efficiency (PCE). It has been discovered that the sliding of A-site cations in the perovskite compound through and out of the three-dimensional [PbI6]4- crystal frame is one of the main reasons that are responsible for decomposition of the perovskite compound. Herein, we report an effective method to enhance the stability of the FA0.79MA0.16Cs0.05PbI2.5Br0.5 perovskite film through the incorporation of n-propylammonium iodide (PAI). Both density functional theory calculation and the X-ray diffraction patterns have confirmed the formation of two-dimensional (PA)2PbI4 with the Ruddlesden-Popper perovskite as a result of the reaction between PAI and PbI2 in the perovskite film. X-ray photoelectron spectroscopy reveals less -COOH (carboxyl) groups on the surface of the perovskite film containing (PA)2PbI4, which indicates the suppressed penetration of oxygen and moisture into the perovskite material. This is further confirmed by the surface water wettability test of the (PA)2PbI4 film that exhibits excellent hydrophobic property with over 110° contact angle. Ultraviolet photoelectron spectroscopy demonstrates the introduction of PAI additives that resulted in the upshift of the conduction band minimum of the perovskite by 160 meV, leading to a more favorable energy alignment with an adjacent electron transporting material. As a consequence, enhanced 17.23% PCE with suppressed hysteresis was obtained with the 5% PAI additive (molar ratio) in perovskite solar cells that retained nearly 50% of the initial efficiency after 2000 h in air without encapsulation under 45% average relative humidity.

Ultrasound‐assisted dispersive micro‐solid‐phase extraction using hydrophobic thiolated ionic liquids immobilized on gold nanoparticles for the preconcentration and determination of amino acids in human plasma samples

AbstractWe describe the pre‐column derivatization of 19 amino acids with o‐phthalaldehyde/2‐mercaptopropionic acid. The derivatives were extracted using an ultrasound‐assisted dispersive micro‐solid‐phase extraction based on hydrophobic thiolated ionic liquids immobilized on gold nanoparticles. For this purpose, 10 mg of adsorbent was added to 10 mL of aqueous sample in the absence of any electrolyte and was inserted in ultrasound bath, which led to the efficient dispersion of adsorbent. The correlation between the extraction efficiency and parameters were optimized using experimental design and response surface methodology. The effects of alkyl‐chain length and anion of hydrophobic thiolated ionic liquids on the surface water wettability of gold nanoparticles were measured. Also, NMR spectroscopy and BET analysis were performed to recognize the formation of thiolated ionic liquids. Transmission electron microscopy, FTIR spectroscopy and X‐ray diffraction were conducted to characterize the gold nanoparticles. The suggested method shows a linear range (0.5–500 μmol L−1) under the optimized conditions with limits of detection in the range of 0.11–0.98 μmol L−1 for analytes. The validated method was successfully used for the quantification of nineteen amino acid derivatives with relative recoveries in the acceptable range of 81.1–104.4% and relative standard deviation less than 4.2%.

Anti-Adherent Biomaterials for Prevention of Catheter Biofouling

Medical device-associated infections present a leading global healthcare challenge, and effective strategies to prevent infections are urgently required. Herein, we present an innovative anti-adherent hydrogel copolymer as a candidate catheter coating with complementary hydrophobic drug-carrying and eluting capacities. The amphiphilic block copolymer, Poloxamer 188, was chemically-derivatized with methacryloyl moieties and copolymerized with the hydrogel monomer, 2-hydroxyethyl methacrylate. Performance of the synthesized copolymers was evaluated in terms of equilibrium swelling, surface water wettability, mechanical integrity, resistance to encrustation and bacterial adherence, and ability to control release of the loaded fluoroquinolone antibiotic, ofloxacin. The developed matrices were able to provide significant protection from fouling, with observed reductions of over 90% in both adherence of the common urinary pathogen Escherichia coli and encrusting crystalline deposits of calcium and magnesium salts relative to the commonly employed hydrogel, poly (hydroxyethyl methacrylate). Additionally, the release kinetics of a loaded hydrophobic drug could be readily tuned through facile manipulation of polymer composition. This combinatorial approach shows significant promise in the development of suitable systems for prevention of catheter-associated infections.

Utilization of Plasma Treated Polymeric Macro-Fibers as Reinforcement in Concrete Constructions

Polymeric macro fibers BeneSteel having diameter equal to 480 μm and length 55 mm were treated in low pressure oxygen plasma by different treatment duration from 5 to 480 s to attain the better interaction with cement matrix (focused on both, chemical and physical bond). An effect of realized treatment was examined through fiber surface water wettability observation by direct horizontal optical method enabling contact angle measurements. Next, the pertinent negative impact of plasma treatment on fibers mechanical properties was examined by several methods. It was shown that the most effective plasma treatment duration is up to 30 s. Thus treated fibers exhibited the better wettability by ca. 110 % in comparison with reference fibers, while its mechanical properties were not negatively affected. Finally, reference and 30 s plasma treated fibers were used as randomly dispersed reinforcement in concrete specimens. Mechanical properties of these composites were examined by four-point bending tests. Specimens containing treated fibers exhibited bigger fracture toughness by ca. 30 % beside the reference ones, while the first cracking strength stayed constant in all cases.

Selective adsorption of bovine hemoglobin on functional TiO2 nano-adsorbents: surface physic-chemical properties determined adsorption activity

Surface functionalized nanoparticles are efficient adsorbents which have shown good potential for protein separation. In this work, we chose two different types of organic molecules, oleic acid (OA) and 3-glycidoxypropyltrimethoxy silane (GPTMS), to functionalize the surface of TiO2 nanoparticles, and we studied the effects of this modification on their surface physicochemical properties in correlation with their selective adsorption of proteins. The results showed that the surface zeta potential and the surface water wettability of the modified TiO2 were significantly changed in comparison with the original TiO2 nanoparticles. The adsorption activities of bovine hemoglobin (BHb) and bovine serum albumin (BSA) on these functionalized TiO2 samples were investigated under different conditions, including pH values, contact time, ion strength, and initial protein concentration. In comparison with the non-specific adsorption of original TiO2, however, both the OA–TiO2 and GPTMS–TiO2 exhibited increased BHb adsorption and decreased BSA adsorption at the same time. Using a binary protein mixture as the adsorption object, a higher separation factor (SF) was obtained for OA–TiO2 under optimum conditions. The different adsorption activities of BHb and BSA on the modified TiO2 were correlated with different interactions at the protein/solid interface, and the chemical force as well as the electrostatic force played an important role in the selective adsorption process.

On novel bio-hybrid system based on PLA and POSS

In this work, a novel strategy for the preparation of bio-hybrid systems based on polylactic acid (PLA) and polyhedral oligomeric silsesquioxane (POSS) was developed. Indeed, the new method consists in a preliminary functionalization of the polymer matrix and a subsequent reaction of silsesquioxane molecules, characterized by amino or hydroxyl functionalities, potentially capable of reacting with maleic anhydride groups created onto PLA by a free radical process. The method adopted to create maleic anhydride-grafted polylactic acid (PLA-g-MA) allowed to graft 0.7 wt% of MA onto the polymer backbone, avoiding a dramatic reduction of PLA molecular mass. 1H-NMR measurements demonstrated a different reactivity of the two used POSS, namely trans-cyclohexanediolisobutyl POSS (POSS-OH) and aminopropyl heptaisobutyl POSS (POSS-NH2). Indeed, the amino group of POSS-NH2 was found to react with the maleic anhydride group of PLA-g-MA allowing to obtain a hybrid system, carrying silsesquioxane molecules along the polymer backbone while the reactivity of POSS-OH turned out to be much lower. Thermal properties of the synthesized hybrid systems were assessed by means of DSC measurements. Indeed, the presence of POSS grafted onto the macromolecular chain was found to improve PLA crystallinity, by affecting the crystal nucleation density. Moreover, a decrease of surface water wettability was observed in the films made of PLA-g-MA/POSS-NH2.

Amine-functionalized multiwall carbon nanotubes impart osteoinductive and bactericidal properties in poly(ε-caprolactone) composites

Amine functionalization of multiwall carbon nanotubes improves mechanical properties, enhances ostoeblast proliferation and mineralization, and imparts bactericidal properties in polycaprolactone composites.

On a novel method to synthesize POSS-based hybrids: An example of the preparation of TPU based system

A novel method to prepare polymer/polyhedral oligomeric silsesquioxanes (POSS) hybrids by melt reactive blending is proposed in this paper, by the controlled polymer chain scission and reaction of chain ends with functional silsesquioxanes. Application to thermoplastic polyurethanes (TPU) is addressed, taking advantage of the polyurethane chain scission equilibrium reaction, leading to the formation of highly reactive isocyanate and hydroxyl chain ends. Despite the isocyanate chemistry has been widely studied for the preparation of polymer/POSS hybrids by in situ copolymerisation, the exploitation of similar chemical processes in an industrially viable and environmental friendly melt blending process is currently an open research field. In this work, the reaction in the molten state of dihydroxyl-functionalised POSS with the polyurethane chain is demonstrated to produce a TPU/POSS hybrids. The effect of POSS concentration on nanomorphol- ogy, thermal properties and surface properties is studied, showing significant changes compared to pristine TPU. In partic- ular, an increase of glass transition temperature is observed in the presence of reactive POSS (!T up to about 10°C in the presence of 10 wt% loading). Furthermore, an increase of surface water wettability, evidenced by the decrease of water contact angle from 95° for pristine TPU to 70° in TPU containing 10wt% of reactive POSS, is found.

Application of tailored silica microspheres in coatings: synthesis, characterization, thermal and hydrophobic properties

Tailored silica microspheres were synthesized using CTAB as a soft template, e.g. solid, mesoporous silica microspheres, solid silica core/mesoporous silica shell (sSiO2@mSiO2) microspheres and hollow silica microspheres. The prepared samples were characterized by SEM, TEM, XRD, and BET. The mechanism of morphological evolution was also proposed based on the experimental results, which reveals the formation processes of solid, mesoporous silica microspheres, solid silica core/mesoporous silica shell (sSiO2@mSiO2) microspheres and hollow silica microspheres. Then silica/silicon resin coatings consisting of the four representative silica particles were prepared. The corresponding FT-IR, UV-Vis spectra and surface water wettability test showed better performance for coatings comprised of the other three silica particles than that of solid SiO2 microspheres. Coatings comprised of mesoporous SiO2 had the best performance of heat insulation and heat preservation and hydrophobic property. The top-view and cross-sectional SEM images and the AFM images of the coatings were also analyzed to explain the relationship between factors such as surface morphology, film thickness, surface roughness of the coating and its related properties.

Reversible wettability of electron-beam deposited indium-tin-oxide driven by ns-UV irradiation

Indium tin oxide (ITO) is one of the most widely used semiconductor oxides in the field of organic optoelectronics, especially for the realization of anode contacts. Here the authors report on the control of the wettability properties of ITO films deposited by reactive electron beam deposition and irradiated by means of nanosecond-pulsed UV irradiation. The enhancement of the surface water wettability, with a reduction of the water contact angle larger than 50°, is achieved by few tens of seconds of irradiation. The analyzed photo-induced wettability change is fully reversible in agreement with a surface-defect model, and it can be exploited to realize optically transparent, conductive surfaces with controllable wetting properties for sensors and microfluidic circuits.

Influences of Electron Beam Irradaiton on Misting and Related Surface Condition on Sapphire Lens

In order to explain the misting-free treatment by sheet electron beam irradiation (SEBI) for sapphire lens setting on endoscope top, influences of SEBI on surface energy are investigated. The SEBI increases surface energy, resulting in force-distance curve used for atomic force microscope. Based on the results of X-ray photoelectron spectroscopy, the SEBI enhances the bonding rates of -C-O- and -C-O-O- and decreases -C-C- bonding rate. On the other hand, influences of SEBI on surface water wettability are investigated. The SEBI enhances the wettability of the sapphire surface for water, n-hexadecan, and 1-bromonaphthalene. Since the adhesion molecular change coincides with the surface energy change, the dipole of adhesion molecular is the dominant factor to control the surface energy. In order to explain to the dipole factor change, the electron charge is measured, too. From the results, the surface energy change can be explained by the adhesion molecular change and electron charging.

Effect of Preadsorbed Proteins on Cell Adhesion to Polymer Surfaces

Adsorption of three different proteins and adhesion of cells onto various substrates in the presence of serum proteins were studied. Both the maximal protein adsorption and the maximal cell adhesion were observed on surfaces with water contact angle around 70°. Preadsorption of serum albumin prevented cell adhesion to all the substrates, whereas preadsorbed fibronectin (FN) enhanced cell adhesion to all the substrates, independent of their water wettability, except for poly(vinyl alcohol) and acrylamide-grafted films. Competitive adsorption of FN from mixed proteins, ranging from 0.03 to 0.07 μg/cm 2, markedly influenced cell adhesion in the presence of serum. These results suggest that the effect of the water wettability of surfaces on cell adhesion in the presence of serum should occur through protein layers adsorbed directly to the substrate surfaces.

A glow discharge treatment to immobilize poly(ethylene oxide)/poly(propylene oxide) surfactants for wettable and non-fouling biomaterials

A non-fouling (protein resistant) polymer surface was achieved using an argon glow discharge treatment of a polyethylene surface which had been precoated with various poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) (PEO-PPO-PEO) tri-block copolymer surfactants. The surfactant is first deposited on the polymer surface via a solvent swelling and evaporation method. Then the coated surfactant is immobilized on the substrate surface by an inert gas discharge treatment. ESCA and water contact angle () measurements on treated and solvent washed surfaces show significant increases in both surface O/C ratios and surface water wettability (0 < 30°) compared to LDPE control surfaces, revealing the presence of PEO on the treated surfaces. A great reduction of fibrinogen adsorption on the modified surfaces is also observed for the highest PEO content surfactants. This simple surface modification process may have wide applicability to obtain wettable polymer surfaces in general, and non-fouling biomaterial surfaces in specific.

Relationship of substratum wettability measurements and initial Staphylococcus aureau adhesion to films and fabrics

The adhesion of Staphylococcus aureus to six films and four fabrics of commercial sources was measured following 1-h contact with the bacteria in aqueous suspensions. Among the untreated and glow-discharged film, increasing S. aureus adhesion was correlated with decreasing surface water wettability as measured by higher water contact angle measurements and lower critical surface tensions. Explicit differences in water wettability (drop absorbency and wicking time) and hydrophobicity (moisture regain) among the untreated as well as among the glow-discharged fabrics were observed. However, little difference in S. aureus adhesion among these two groups of fabrics indicates that the water wettability and hydrophilicity measurements of the fabrics were not the domainant factors attributing to their S. aureus adhesion properties. Different correlations between surface wettability and S. aureus adhesion on films and fabrics of similar chemical compositions further suggest that S. aureus adhesion may be influenced by other surface properties due to their different fabrication and finishing processes. Glow discharge improved wetting characteristics of both types of substratum, but S. aureus adhesion on fabrics was lowered and that on films was increased by the treatment. The bacteria—water wettability correlation on glow—discharged discharge induced active species on the surface.