Decrease In Water Contact Angle Research Articles

Poly (caprolactone)/poly (ethylene glycol) pervaporation blend membranes: Synthesis, characterization, and performance

Poly (caprolactone) membranes with addition of different poly (ethylene glycol) concentrations were prepared for separation of water/isopropanol azeotropic mixture by pervaporation process. Different characterization tests including Fourier transform infrared, scanning electron microscopy, water contact angle, and thermogravimetric analysis were carried out on the prepared membranes. In addition, the effect of poly (ethylene glycol) PEG content on the swelling degree and the performance of the prepared membranes in pervaporation process were investigated. According to the obtained results, all the membranes were water selective and the blend membrane containing 3 wt% PEG exhibited the best pervaporation performance with a water flux of 0.517 kg/m2 hour and separation factor of 1642 at the ambient temperature. Hydrophilicity improvement of the blend membranes was confirmed by constant decrease in water contact angle of the membranes as PEG content increased in the casting solution. Scanning electron microscopy cross‐sectional images indicated that the blend membranes containing PEG had a closed cellular structure. Furthermore, mechanical and thermal properties of the membranes decreased by adding PEG.

The effect of polycrystalline graphene on corrosion protection performance of solvent based epoxy coatings: Experimental and DFT studies

In this research, the effect of polycrystalline graphene (PG) on corrosion protection performance of epoxy coating is investigated. Various quantitative and qualitative characterization techniques of X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Porosimety were employed for characterizing the sample and studying the structure of morphology of the PG. Furthermore, the field emission scanning electron microscopy was considered for investigating the PG dispersion in coating. The corrosion protection performance of epoxy coatings containing different wt.% of PG (0.05, 0.1, 0.3, and 0.5) is evaluated by electrochemical impedance spectroscopy. The results obtained using the prepared nanocomposite showed that the nanocomposite coatings provided higher corrosion resistance compared with the pure epoxy. Meanwhile, nanocomposites containing 0.05 wt% PG show superior corrosion resistance and lower wettability (∼12% decrease in water contact angle). The PG sheets agglomerate in matrix by increasing the loading of PG, leading to increase of hydrophilicity and decrease of corrosion protection. Also, the quantum chemical calculations and Density Functional Theory are performed which confirmed the better performance of the epoxy/PG nanocomposite compared with pure samples.

Electrospun Chitosan/Poly(ethylene oxide)/Lauric Arginate Nanofibrous Film with Enhanced Antimicrobial Activity.

In this study, chitosan/poly(ethylene oxide) (PEO)/lauric arginate (LAE) composite nanofibrous films were fabricated via electrospinning. The addition of LAE did not change the physical properties of chitosan/PEO in acetic aqueous solutions, but increased the fluorescent intensity of chitosan by electrostatic interactions, resulting in uniform and bead-free nanofibers with an average diameter of 150 nm. The Fourier transform infrared spectra and thermal analysis indicated that the LAE molecules were homogeneously dispersed within the chitosan/PEO nanofibers. The formation of electrostatic and hydrogen bonding interactions induced by the LAE addition changed the inter- and intramolecular interactions between PEO and chitosan and further affected the mobility of the polymer molecules, leading to the increased crystallinity and decreased melting point. The hydrophilicity of the nanofibrous films was significantly increased by the incorporation of LAE, as indicated by the decreasing water contact angle from 39° to 10°. Meanwhile, the chitosan/PEO/LAE nanofibrous films showed LAE concentration dependent antimicrobial activity against Escherichia coli and Staphylococcus aureus, suggesting enhanced antimicrobial activity. The fluorescent staining experiments demonstrated that the antimicrobial mechanism of the nanofibrous films was cell membrane damage.

The surface wettability of TiO2 nanotube arrays: which is more important—morphology or chemical composition?

The wettability of TiO2 nanotube arrays (TiO2-NTAs) synthesized by electrochemical anodization was intensively investigated. It was found that annealing temperature of TiO2-NTAs has significant effect on the hydrophilicity of TiO2-NTAs. With the increase of annealing temperature, the fluorine element content on TiO2-NTAs surface decreases, which results in decrease in water contact angle and increase in hydrophilicity for TiO2-NTAs. The reason is that F− ions escape from the lattice and oxygen vacancies are created at the two coordinated oxygen bridging sites at TiO2-NTAs surface after annealing in argon atmosphere. And these defects can in turn increase the affinity for hydroxyl ions formed by dissociation of chemisorbed water molecules and thereby form hydrophilic domains. In addition, TiO2 crystal becomes well organized gradually with the increase of annealing temperature, F− ions are not favored to exist in the lattice and thus escape from the lattice. Less F element content results in better hydrophilicity of TiO2-NTAs.

An oxygen plasma treated poly(dimethylsiloxane) bioscaffold coated with polydopamine for stem cell therapy.

In this study, 3D macroporous bioscaffolds were developed from poly(dimethylsiloxane) (PDMS) which is inert, biocompatible, non-biodegradable, retrievable and easily manufactured at low cost. PDMS bioscaffolds were synthesized using a solvent casting and particulate leaching (SCPL) technique and exhibited a macroporous interconnected architecture with 86 ± 3% porosity and 300 ± 100 µm pore size. As PDMS intrinsically has a hydrophobic surface, mainly due to the existence of methyl groups, its surface was modified by oxygen plasma treatment which, in turn, enabled us to apply a novel polydopamine coating onto the surface of the bioscaffold. The addition of a polydopamine coating to bioscaffolds was confirmed using composition analysis. Characterization of oxygen plasma treated-PDMS bioscaffolds coated with polydopamine (polydopamine coated-PDMS bioscaffolds) showed the presence of hydroxyl and secondary amines on their surface which resulted in a significant decrease in water contact angle when compared to uncoated-PDMS bioscaffolds (35 ± 3%, P < 0.05). Seeding adipose tissue-derived mesenchymal stem cells (AD-MSCs) into polydopamine coated-PDMS bioscaffolds resulted in cells demonstrating a 70 ± 6% increase in viability and 40 ± 5% increase in proliferation when compared to AD-MSCs seeded into uncoated-PDMS bioscaffolds (P < 0.05). In summary, this two-step method of oxygen plasma treatment followed by polydopamine coating improves the biocompatibility of PDMS bioscaffolds and only requires the use of simple reagents and mild reaction conditions. Hence, our novel polydopamine coated-PDMS bioscaffolds can represent an efficient and low-cost bioscaffold platform to support MSC therapies.

Resistance to corona discharge of HTV silicone rubber surface layers fluorinated at different temperatures

In order to investigate the effect of fluorination temperature on the resistance to corona discharge of HTV silicone rubber, HTV silicone rubber samples were fluorinated using a F2/N2 mixture at temperatures of 25, 55, and 85 °C for 30 min. The surface fluorinated and unfluorinated (virgin) samples were simultaneously exposed to corona discharge generated by a multi-needle-to-plate electrode system. ATR-IR analysis and SEM observation indicate that the virgin surface layer is severely oxidized and degraded by corona discharge. In contrast with this, the surface layer fluorinated at 85 °C does not show obvious changes in the chemistry, surface morphology and thickness after corona exposure. However, the corona exposure led to definite changes in both the chemistry and surface morphology of the surface layer fluorinated at 55 °C, and its corona-resistance property appears to be worse than the surface layer fluorinated at 25 °C. The abnormal effect of fluorination temperature on corona resistance is explained by unusual changes of surface physicochemical characteristics with fluorination temperature. Measurements of contact angle show a much higher water contact angle on the fluorinated surfaces than the virgin surface before corona exposure, an initial significant decrease in water contact angle for all the surfaces just after the end of the corona exposure, and the subsequent recovery of contact angle only for the exposed virgin surface. Measurements of surface potential reveal that the potential decay rate obviously increases for the virgin sample after corona exposure, while the decay rate decreases rather than increases for the fluorinated samples after the same exposure. There is no significant difference in surface properties between the fluorinated samples before or after corona exposure. This is considered to be due to the combined effect of compositional and structural changes and the fact that the surface properties are very sensitive to the top several molecular layers.

Activation of polycarbonate (PC) surfaces by atmospheric pressure plasma in ambient air

This paper presents the study of the ambient air atmospheric pressure plasma (APP) treatment of polycarbonate (PC) surfaces to improve the wettability. The APP was generated by dielectric barrier discharge of coplanar electrode arrangement: a Diffuse Coplanar Surface Barrier Discharge (DCSBD), and gliding arc APC 500. The changes in wettability of the PC surfaces were characterized by water contact angle measurement, hysteresis analysis of the water contact angle and surface free energy. We found that both plasma sources led to considerable decrease of water contact angle in first second of the treatments. Surface free energy analysis explained, that the decrease of the water contact angle was related to higher polar components of the surface. The modification of the PC surfaces was further evaluated by X-ray photoelectron spectroscopy that showed that both plasma sources led to increase in concentration of polar functional groups on the PC surface. The main difference between DCSBD and APC plasmas was in the surface morphology which observed by atomic force microscopy (AFM).

Graphene quantum dots modified polyvinylidenefluride (PVDF) nanofibrous membranes with enhanced performance for air Gap membrane distillation

This study investigates the potential of novel graphene quantum dots (GQDs)/polyvinylidene fluoride (PVDF) nanofibrous membranes for water desalination via air gap membrane distillation (AGMD) process. Different contents of GQDs were loaded in/on nanofibrous membrane for obtaining the desired structure for AGMD process. The resultant GQDs/PVDF nanofibrous presented a slight decrease in water contact angle and considerable increase in liquid entry pressure of water (LEPw). The sample containing 0.25 wt.% GQDs exhibited porosity of >90%, LEPw of >135 kPa, mean average surface roughness of 189.24 nm and water contact angle of >125°. Furthermore, the BET analysis exhibited that the mean pore diameter and effective surface area of nanofibrous membrane were modified at presence of GQD. AGMD experiments indicated that the higher water flux of 17.6 kg/m2 h and salt rejection of about 99.7% were achieved for GQD3P membrane containing 0.25 wt% GQDs compared to neat PVDF nanofibrous membrane with water flux of about 14.7 kg/m2 h and salt rejection of about 94.5% (partial wetting occurred after 4 h) during filtration of 3.5 wt.% NaCl solution for 8 h under feed and permeate temperatures of 60 °C and 20 °C, respectively. Eventually, GQD3P exhibited the water flux of 10.8 kg/m2h and reliable salt rejection of >99.5% over 60 h experiment.

Microstructures and performances of pegylated polysulfone membranes from an in situ synthesized solution via vapor induced phase separation approach

In situ pegylated (PEGylated) microporous membranes have been extensively reported using poly(ethylene glycol) (PEG)-based polymers as blending additives. Alternatively, free standing PEGylated polysulfone (PSf) membranes with excellent hydrophilicity and antifouling ability were directly fabricated from polysulfone/poly(ethylene glycol) methyl ether methacrylate (PSf/PEGMA) solutions after in situ cross-linking polymerization without any treatment via vapor induced phase separation (VIPS) process for the first time. The microstructures and performances of the resulting membranes shifted regularly by adjusting exposure time of the liquid film in humid air. With increasing exposure time, plenty of worm-like networks formed and distributed on membrane surfaces, meanwhile cross-sectional morphology changed from asymmetric finger-like microporous structure to symmetric cellular-like structure, resulting in better mechanical stability. As the exposure time raised from 0 to 5 min, the surface coverage of carboxyl groups increased from ∼1.1 to 4.0 mol%, leading to the decrease in water contact angle from ∼63 to 27° and the increase in water flux from ∼110 to 512 L m−2 h−1. In addition, at prolonged exposure time, increasing hydrophilic PEG chains migrated to membrane surfaced and repelled the adsorption and deposition of protein, resulting in better antifouling ability. The findings of this study offer a facile and high efficient strategy for flexible design and fabrication of the in situ PEGylated membranes with desirable structures and performances in large scale.

Modified Polysulfone Ultrafiltration Membrane for Humic Acid Removal During Peat Water Treatment

In this research, UF membrane was prepared by blending polysulfone (PSf) in DMAc with the addition of PEG400 and low concentration of acetone as additives. The effect of PSf/PEG400 and polymer/solvent ratio on the performance of PSf membrane was investigated during two hours of peat water filtration. The results showed that the increase of ratio PSF/PEG400 from 1:1 to 1:2.5 improved the membrane hydrophilicity. It was indicated by a decrease of water contact angle from 62° to 33° and increased water content in membrane structure from 65 to 74,5%. In addition, the pure water flux also increased up to 200 times. A stable flux is achieved when the ratio PSf/PEG is 1:2 and resulted in 84% rejection of humic acid. The increase of polymer concentration in the membrane solution reduced the pure water flux but increased the rejection of humic acid. Higher polymer concentration in membrane solution reduced fouling tendency towards the membrane surface. It showed that flux decline was reduced from 60% to 40% when the ratio of polymer/solvent concentration was changed from 40/60 to 50/50.

Promoting Endothelial Cell Affinity and Antithrombogenicity of Polytetrafluoroethylene (PTFE) by Mussel-Inspired Modification and RGD/Heparin Grafting.

When used as small-diameter vascular grafts (SDVGs), synthetic biomedical materials like polytetrafluoroethylene (PTFE) may induce thrombosis and intimal hyperplasia due to the lack of an endothelial cell layer. Modification of the PTFE in an aqueous solution is difficult because of its hydrophobicity. Herein, aiming to simultaneously promote endothelial cell affinity and antithrombogenicity, a mussel-inspired modification approach was employed to enable the grafting of various bioactive molecules like RGD and heparin. This approach involves a series of pragmatic steps including oxygen plasma treatment, dopamine (DA) coating, polyethylenimine (PEI) grafting, and RGD or RGD/heparin immobilization. Successful modification in each step was verified via Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Plasma treatment increased the hydrophilicity of PTFE, thereby allowing it to be efficiently coated with dopamine. Grafting of dopamine, RGD, and heparin led to an increase in surface roughness and a decrease in water contact angle due to increased surface energy. Platelet adhesion increased after dopamine and RGD modification, but it dramatically decreased when heparin was introduced. All of these modifications, especially the incorporation of RGD, showed favorable effects on endothelial cell attachment, viability, and proliferation. Due to strong cell-substrate interactions between endothelial cells and RGD, the RGD/heparin-grafted PTFE demonstrated high endothelial cell affinity. This facile modification method is highly suitable for all hydrophobic surfaces and provides a promising technique for SDVG modification to stimulate fast endothelialization and effective antithrombosis.

Ultraviolet-Durable Superhydrophobic Nanocomposite Thin Films Based on Cobalt Stearate-Coated TiO2 Nanoparticles Combined with Polymethylhydrosiloxane.

Ultraviolet (UV)-durable superhydrophobic nanocomposite thin films have been successfully fabricated on aluminum substrates by embedding cobalt stearate (CoSA)-coated TiO2 nanoparticles in a hydrophobic polymethylhydrosiloxane (PMHS) matrix (PMHS/TiO2@CoSA) using the sol–gel process. When compared to the sharp decrease of water contact angle (WCA) on the superhydrophobic PMHS/TiO2 thin films, the PMHS/TiO2@CoSA superhydrophobic thin films exhibited a nearly constant WCA of 160° under continuous UV irradiation for more than 1 month. The designed scheme of the TiO2@CoSA core–shell structure not only increased the hydrophobic properties of the TiO2 nanoparticle surface but also confined the photocatalytic efficiency of TiO2 nanoparticles. A plausible model has been suggested to explain the UV-durable mechanism of the superhydrophobic nanocomposite thin films based on PMHS/TiO2@CoSA. Furthermore, the elongated lifetime in the exposure of the solar light imparts this superhydrophobic nanocomposite thin film with potential practical applications where UV-resistant properties are emphasized including corrosion-resistant building walls, anti-icing airplanes, self-cleaning vehicles, and so forth.

Evaluation of cell activation promoted by tantalum and tantalum oxide coatings deposited by reactive DC magnetron sputtering

Previous studies have shown both Ta and TaO to be bioactive, rapidly forming a strongly-bonded surface-adherent layer of bone-like hydroxyapatite (HAp) when immersed in simulated body fluid (SBF). Consequently, Ta and TaO coatings are promising for the surface-modification of Ti or stainless steel endodontic endosseous implants, being conducive to a reduction in the risk of developing post-operatory infection and/or peri-implantitis disease. That said, few studies have investigated the effect of Ta or TaO coatings on such phenomena as cell activation, adhesion, and proliferation.To that effect, Ta, and TaO films were deposited onto type 316L stainless steel (SS 316L) substrates by reactive DC magnetron sputtering, after which their biological response was evaluated following co-incubation with the murine macrophage-like cell line RAW 264.7. Cell morphology after adhesion was observed by SEM, whereas cell viability and proliferation were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Lastly, inflammatory response was assessed by quantification of the cytokines interleukin-6 (IL-6) and interleukin-10 (IL-10).In terms of phase composition, Ta showed a mixture of the α-Ta and β-Ta phases, whereas TaO showed a nanocrystalline structure. Moreover, a decrease in average roughness (Ra) from 21nm to 7nm was observed between Ta and TaO, accompanied by a decrease in water contact angle (θW) from 106° to 83°.In vitro studies showed that cells exhibited significantly better adhesion to Ta, in comparison with both TaO and SS 316L. Furthermore, both Ta and TaO were shown to be non-cytotoxic, with Ta outperforming TaO in terms of relative cell viability, both at 24h and 48h. Lastly, both Ta and TaO showed vastly inferior IL-6 and IL-10 levels to those obtained for cells treated with bacterial lipopolysaccharides (LPS)—prompting the conclusion that the coatings do not in any way induce an inflammatory response from macrophage cells.

Film Confinement Induced "Jump-Percolation" Wetting Transition in Amphiphilic Block Copolymer Films.

We report a first-order like sharp surface wettability transition with varying film thickness dependent morphology in cast films of an amphiphilic triblock copolymer. Films composed of poly(2-(N-ethylperfluorooctanesulfonamido) ethyl methyl acrylate), poly(FOSM), and poly(N,N'-dimethyl acrylamide), poly(DMA), with thickness (h) in the transition-range, 200 < h < 300 nm, exhibited an abrupt hydrophobic to hydrophilic dynamic water contact angle transition. After an induction time, ti ≈ 40 to 180 s, water contact angle varied as θc ≈ 116° to 40° with an ultrafast contact angle decay time constant, [Formula: see text] ≈ -18°/s. This behavior is a result of competing heterogeneous and antagonistic effects of bumpy poly(DMA) wetting domains against a nonwetting planar poly(FOSM) background, with a "jump percolation" wetting transition when the poly(DMA) domain density reaches unity. Outside of this film thickness range, relatively shallow decreasing water contact angle gradients were observed with a monotonically increasing poly(DMA) domain area coverage with increasing film thickness in the overall range of 40 nm (hydrophobic, θc ≈ 118°) < h < 500 nm (hydrophilic, θc ≈ 8°). The optical diffuse reflectance properties of these rough surfaces exhibit an onset of diffuse reflectance maxima correlated to the transition morphology film thickness.

Impact of pre-incubation time of silk fibroin scaffolds in culture medium on cell proliferation and attachment.

Cell behaviours such as proliferation and attachment can be affected by the length of pre-incubation period of the scaffolds in the culture medium for long term. The aim of this study was to investigate the long term pre-incubation of 3D silk fibroin scaffolds in complete culture medium on cell attachment and proliferation. After the preparation of silk fibroin scaffolds by the technique of freeze drying, the scaffolds were pre-incubated in complete culture medium for 2 d, 6 d or 10 d before apical papilla stem cells (SCAP) seeding. Modifications of the scaffold surface and wettability were examined by FE-SEM and water contact angle, respectively. Results showed a decrease both in roughness and water contact angle as pre-incubation time increases. DNA measurement after 18h and 10 d cell seeding showed a significant increase of DNA concentration which represents better attachment and proliferation with pre-incubation time increase. Qualitative examination, live&dead assay or H&E staining method after 30h and 10 d cell seeding respectively, indicated that pre-incubation of scaffolds has time dependent effect on cell proliferation and attachment. This suggests that improvement of cell attachment and proliferation may be mediated by differences in the amount of wettability (decreased water contact angle) after exposure of scaffold to culture medium for long term which, in turn, causes more protein adsorption in the surface of silk fibroin scaffold (decreased roughness).

In-situ grafting to improve polarity of polyacrylonitrile hollow fiber-supported polydimethylsiloxane membranes for CO2 separation

Surface grafting modification was proposed to improve the surface polarity of polyacrylonitrile hollow fiber-supported polydimethylsiloxane (PDMS) membrane. The initiator 3-aminopropyltriethoxysilane containing one amine group was integrated into PDMS, and polyvinyl pyrrolidone (PVP) with strong polarity was connected to the surface by reacting with amine groups. Surface grafting modification was proven on X-ray photoelectron spectroscopy. The sharp decrease (from ∼98° to ∼28°) in water contact angle of the PDMS membrane indicated the significant improvement in surface polarity after the modification. The surface roughness of the PDMS membrane increased with the modification, and the PDMS surface immersed for 40s was almost covered with PVP. The membrane immersed in PVP solution for 10s improved CO2/H2, CO2/CH4, and CO2/N2 selectivities. While CO2 permeance slightly decreased from ∼2500 GPU to ∼2440 GPU. For the separation of CO2/CH4 and CO2/N2 mixed gases, all CO2/CH4 and CO2/N2 selectivities were improved after the modification. For the separation of CO2/H2 mixed gas, CO2/H2 selectivity was improved when the immersion time was below 30 s.

Mechanisms of atmospheric pressure plasma treatment of BOPP

Surface energy increase of polymers with plasma treatment is an industrially significant process. The mechanisms behind this process are little understood, with work addressing the water contact angle decrease with treatment and changes in surface chemistry. Work presented here addresses the mechanism of this surface energy increase, by using crystalline biaxially orientated polypropylene (BOPP) films to identify plasma induced structural changes. Increased crystallinity of the BOPP films were observed by ATR‐FTIR spectroscopy, indicating preferential oxidation of amorphous regions of the BOPP films by the plasma. This crystal structure change correlates with XRD peak shifts, implying relaxation of crystal regions into regions previously occupied by amorphous BOPP. The trend in surface energy increases also correlates with the effective increase in crystallinity.

Fabrication of polyacrylonitrile-coated kapok hollow microtubes for adsorption of methyl orange and Cu(II) ions in aqueous solution

Polyacrylonitrile (PAN)-coated kapok hollow microtubes were synthesized using a facile surfactant-assisted method. Cetyltrimethylammonium bromide (CTAB) was employed to assist in polymer deposition and arrangement. The kapok fibers retained its hollow microtube structure after PAN coating. A drastic decrease in water contact angle from 133.43 to 0° was also determined. Generally, thicker and more uniform PAN coating was achieved at higher concentration of CTAB. On the other hand, addition of larger amount of AN resulted in thicker PAN coating. Batch experiments were utilized to investigate the effect of contact time and temperature on the adsorption efficiency of methyl orange dye and Cu(II) from aqueous solution. Isotherm studies revealed that removal of methyl orange and Cu(II) follow the Langmuir isotherm model, with maximum adsorption capacity of 34.72 and 90.09 mg/g, respectively. This suggests that Cu(II) is preferentially adsorbed on the PAN-kapok fibers over methyl orange. Kinetic studies show that the adsorption of methyl orange and Cu(II) on PAN-kapok follow a pseudo-second order kinetic model, indicating chemisorption as the rate-determining step. Based on thermodynamic data, both Cu(II) and methyl orange adsorption is spontaneous and endothermic.

Development and characterisation of chitosan or alginate-coated low density polyethylene films containing Satureja hortensis extract

This study aimed to develop novel bilayer films based on alginate, chitosan and low-density polyethylene (LDPE) containing different concentrations of summer savory extract (SSE). The cold atmospheric plasma system was used to increase the surface energy of LDPE. Initially, water contact angle, surface roughness and the functional group of LDPE before and after plasma treatment were investigated. Then physical, mechanical, optical, antioxidant and microstructure properties of plasma-treated and untreated bilayer films and antioxidant films incorporated with SSE were characterized. Results showed that plasma treatment increased oxygen-containing the polar group, surface roughness and decreased water contact angle of LDPE surface (from 90.47° to 48.73°) and in result enhanced adhesion between polysaccharide coating and LDPE. Tensile strength of both alginate and chitosan coated-LDPE increased from 10.096 to 14.372 and 11.513 to 13.459MPa, respectively after plasma pretreatment. However chitosan-based films had lower water solubility. Although, incorporation of SSE into chitosan and alginate coated-LDPE despite slight adverse effects on the physical and mechanical properties of films, it provided antioxidant activity. Chitosan coated-LDPE containing SSE had potential to use as antioxidant food packaging.

Enhanced flux performance of polyamide composite membranes prepared via interfacial polymerization assisted with ethyl formate.

A novel thin film composite (TFC) polyamide reverse osmosis membrane was prepared via the interfacial polymerization of m-phenylene diamine (MPD) in aqueous phase and 1,3,5-trimesoyl chloride (TMC) in organic phase on a polysulfone ultrafiltration support by assisting with ethyl formate as a co-solvent added in the organic phase. The ethyl formate added in the organic phase is intended to form a narrow miscibility zone, which leads to the thicker reaction zone. The multi-layered loose polyamide structure with larger pore size was formed due to the thicker reaction zone and lower content of MPD. The enhanced hydrophilicity of the membrane was proved by the decreased water contact angle. Water flux was measured at 1.6 MPa with 2,000 ppm NaCl aqueous solution. Compared to the TFC membrane prepared without ethyl formate, the water flux across the TFC membrane with ethyl formate in the organic phase increased with the increased ethyl formate content (from 23 to 45 L/(m2 h)) and the salt rejection remained at a high level (>90%). The ethyl formate can be used as a co-solvent to effectively enhance the performance of the TFC membrane.