Mechanically Robust Nanofibrous Xerogel Membrane for One‐Pass Removal of Trace Water in Oil

Removal of trace water from oil is essential for a high‐performance fuel supply system. Trace water in fuel is a crucial contributor to frequent system maintenance and failure. In this work, an electrospun polyacrylic acid/polyvinyl alcohol (PAA/PVA) nanofibrous xerogel membrane (NFM) is prepared to remove trace water in oil. Based on the optimization of the weight ratio and the crosslinking conditions of PAA/PVA, the resultant NFM shows remarkable water‐retaining capacity (swelling ratio of 124.8 g/g) and rapid absorption property. The optimal membrane displays a small average pore size of 523.2 nm, high porosity of 79.6% as well as robust tensile strength of 8.1 MPa. Additionally, after just one pass through a single layer membrane (thickness of 35 ± 3 µm and areal density of 3.5 ± 0.5 g m^?2), the milky oil containing 1 wt% water is clarified and the water content reduced to 130 ppm. With extensive water being absorbed into the 3D network (different with the conventional separation mechanism) as well as good compatibility with oil, a multilayer pleated scheme may provide a practical methodology for enhancing fuel oil properties and performances.     

Synthesis of water‐glass‐based silica aerogel powder via with and without squeezing of hydrogels

The present article describes the synthesis of water‐glass‐based silica aerogel powder via coprecursor method, using with and without squeezing, in drying technique. The present research was aimed to develop a simple, cost‐effective, and rapid drying process, i.e., squeezing through sol–gel synthesis. The physical and textural properties of the aerogel powder synthesized with and without squeezing process via ambient pressure drying (APD) have been studied and compared. For characterization of aerogel powder, we employed Brunauer, Emmett, and Teller, Barrett‐Joyner‐Halenda, and field emission scanning electron microscope techniques. The experimental results showed that the properties of the aerogel powder obtained by squeezing are superior to those dried in a furnace one. The squeeze‐dried aerogel powder exhibited lower tapping density (0.126 g/cm³) than furnace dried. Furthermore, textural investigations revealed that the aerogel powder has high‐specific surface area (752.3 m²/g), high porosity, low shrinkage, and uniform pore size distribution, which is obtained by squeezing process via APD. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

One‐Pot Route for Fe@Poly(styrene‐co‐divinylbenzene) Foam with Robust Physical/Chemical Stability and Remote Magnetic Driven Capacity for Oil Removal

Magnetic and superhydrophobic materials with robust physical/chemical stability for controllable and remote magnetic driven capacity for oil removal under harsh environments are meaningful for oil–water separation but still a challenge. Herein, an alternative strategy to address this challenge is demonstrated by decorating poly(styrene‐co‐divinylbenzene) (PSDVB) on Fe foam via one‐pot solvothermal method. Different from previous magnetic and superhydrophobic materials, Fe foam is chosen to replace Fe₃O₄ nanomaterials. Thus, complicated preparation procedures and the high cost for Fe₃O₄ nanomaterials can be avoided. Additionally, PSDVB coating provides the whole foam with robust physical/chemical stabilities: i) the surface wettability can be maintained after 50 abrasion cycles or exposed in humid air (relative humidity: 90%) for 14 days, and ii) the surface wettability does not change under different pH solutions (3 < pH < 12) or highly salty solution (NaCl 10 wt%) for 6 h. Besides, outstanding separation efficiency (>99.9%), high durability (>70 times), and excellent oil flux (16 963–75 156 L m^?2 h^?1) can be realized under gravity. Most importantly, the foam continuously removes oil from confine place (on water surface or under water) under magnetic driven force.     

Three‐dimensionally printed bioinspired superhydrophobic PLA membrane for oil‐water separation

A novel lotus‐leaf‐inspired superhydrophobic poly(lactic acid) (PLA) porous membrane was fabricated for oil‐water separation based on fused deposition modeling three‐dimensional printing and subsequent chemical etching and the decoration of polystyrene nanospheres. A superhydrophobic PLA fractal surface with a water contact angle of 151.7° and low water adhesion force of 21.8 μN was achieved. The membrane pore size could be easily adjusted from 40 to 600 μm via a computer‐aided design program to optimize separation performance. The maximal oil‐water separation efficiency of 99.4% was achieved with a pore size of 250 μm, which also exhibited a high flux of 60 kL m^?2 h^?1. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3700–3708, 2018     

Polyion Complex Nanofibrous Structure Formed by Self‐Assembly of Chitosan and Poly(acrylic acid)

Summary: An ideal scaffold design has a nanofibrous structure that can replace the natural extracellular matrix (ECM) until host cells can repopulate and resynthesize a new natural matrix. In this study, chitosan (CS)‐poly(acrylic acid) (PAA) nanofibers with diameters that range from 50 to 150 nm are synthesized successfully by a modified dropping method. Exactly how various carboxylic acid solvents affect the formation of CS‐PAA nanofibrous complex is also discussed. The results show that using adipic acid as a solvent to dissolve CS, adjusting the final pH value of the CS solution to 3, and then dropping the CS solution into the PAA solution at a ratio of 3:1, cause a significant reaction of CS with PAA and the nanofibers are dispersed uniformly. After freeze‐drying, a 3‐D interconnected CS‐PAA nanofibrous scaffold with a fiber diameter that ranges from 50 to 200 nm can be obtained. The CS‐PAA nanofibrous matrix is of particular interest in tissue engineering for controlled drug release and tissue remodeling.

Nanofibrous structure via polyion complex formation between chitosan and poly(acrylic acid).     

Synthesis of (Z)‐3‐hexen‐1‐yl acetate by lipase immobilized in polyvinyl alcohol nanofibers

Polyvinyl alcohol (PVA)‐nanofibers‐immobilized lipase were formed by electrospinning. The specific surface area of the nanofiber (5.96 m²/g) was about 250 times larger than that of PVA‐film‐immobilized lipase (0.024 m²/g). The PVA‐nanofibers‐immobilized lipase were used as the catalyst for the esterification of (Z)‐3‐hexen‐1‐ol (leaf alcohol) with acetic acid in hexane. The activity of the nanofiber is equivalent to that of commercially available immobilized lipase (Novozym‐435). The ester conversions of the nanofibers, Novozym‐435, the film and lipase powder reached 99.5% at 5 h, 100% at 5 h, 11.5% at 6 h, and 81.1% at 5.75 h, respectively. The nanofibers‐immobilized lipase showed higher activity for the esterification than the film‐immobilized lipase and lipase powder, probably because it has high specific surface area and high dispersion state of lipase molecules in PVA matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Water‐Resistant Poly(vinyl alcohol)‐Silica Hybrids through Sol‐Gel Processing

Poly(vinyl alcohol) (PVA)‐silica hybrids with exceptionally reduced solubility in water were synthesized. The hybrid xerogels were fabricated through sol‐gel processing of a mixture of PVA and the acid‐catalyzed silica precursor tetraethoxysilane. The effects of varying ratios of PVA and silica precursor on the surface structure, thermal properties, crystallinity, and solubility of the hybrids were investigated. Unlike the highly water‐soluble nature of PVA, all the hybrids displayed considerably reduced solubility in water. This anomalous behavior of PVA in the hybrids can be attributed to the unavailability of its pendant –OH groups. Water‐resistant PVA‐silica hybrids can find applications in various technologies requiring biocompatible systems that are stable in aqueous environments.     

Biocompatibility studies of electrospun nanofibrous membrane of PLLA‐PVA blend

Electrospinning, self‐assembly, and phase separation are some of the techniques available for the synthesis of nanofibers. Of these techniques, electrospinning is a simple and versatile method for generating ultrafine fibers from a wide variety of polymers and polymer blends. Poly L ‐lactide (PLLA) and Poly (vinyl alcohol) (PVA) are biodegradable and biocompatible polymers which are mainly used for biomedical applications. Nanofibrous membranes with 1:9 ratio of PLLA to PVA (8 to 10 wt % and 10 wt %) were fabricated by electrospinning. The percentage porosity and contact angle of PVA in the PLLA‐PVA nanofibrous mat increased from 80 to 83% and from 39 ± 3° to 55 ± 3°, respectively. The water uptake percentage of PVA nanofibers decreased from 190 to 125% on the addition of PLLA to PVA in the PLLA‐PVA nanofibrous mat. The nanofiber morphology, structure and crystallinity were studied by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT‐IR), and X‐ray diffraction (XRD), respectively. The thermal properties were studied by thermogravimetric analysis (TGA) and differential scanning calorimetery (DSC). The biocompatibility studies of PLLA‐PVA blend were performed using fibroblast cells (NIH 3T3) by MTT assay method. The release of Curcumin (0.5, 1.0, and 1.5 wt %) from PLLA‐PVA blend was found to be ～ 78, 80, and 80%, respectively, in 4 days. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Properties of electrospun poly(vinyl alcohol) hydrogel nanofibers crosslinked with 1,2,3,4‐butanetetracarboxylic acid

ABSTRACT: Electrospun nanofibrous hydrogel membranes have been gaining significant importance due to the combination of unique physical properties of nanofibers and biocompatibility of hydrogels. Thus, they are considered as potential candidates for medical textile applications. This study deals with electrospinning of poly(vinyl alcohol) (PVA) hydrogel nanofibrous membranes. The chemical crosslinking of PVA with proportionate quantities of 1,2,3,4 butanetetracarboxylic acid (BTCA) was undertaken to form hydrogel structures. Cross‐linked membranes were characterized by scanning electron microscopy, FT‐IR and thermogravimetric analysis, water swelling, and durability tests. FT‐IR analysis demonstrated the formation of ester linkages between PVA and BTCA and thermogravimetric analysis showed that crosslinking improved the thermal stability of the nanofibrous structure. Furthermore, the results indicated that crosslinking with BTCA improved water stability of PVA membranes and the nanofibrous structure was preserved after water treatment. It is envisaged that use of BTCA as a cross‐linker to form hydrogel nanofibers could be a practical and a promising method for medical textile applications, especially for wound dressings given its nontoxicity and immiscibility with polymer solutions. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and swelling properties of semi‐IPN hydrogels based on chitosan‐g‐poly(acrylic acid) and phosphorylated polyvinyl alcohol

The phosphorylated poly(vinyl alcohol) (P‐PVA) samples with various substitution degrees were prepared through the esterification reaction of PVA and phosphoric acid. By using chitosan (CTS), acrylic acid (AA) and P‐PVA as raw materials, ammonium persulphate (APS) as an initiator and N,N‐methylenebisacrylamide as a crosslinker, the CTS‐g‐PAA/P‐PVA semi‐interpenetrated polymer network (IPN) ssuperabsorbent hydrogel was prepared in aqueous solution by the graft copolymerization of CTS and AA and followed by an interpenetrating and crosslinking of P‐PVA chains. The hydrogel was characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) techniques, and the influence of reaction variables, such as the substitution degree and content of P‐PVA on water absorbency were also investigated. FTIR and DSC results confirmed that PAA had been grafted onto CTS backbone and revealed the existence of phase separation and the formation of semi‐IPN network structure. SEM observations indicate that the incorporation of P‐PVA induced highly porous structure, and P‐PVA was uniformly dispersed in the polymeric network. Swelling results showed that CTS‐g‐PAA/P‐PVA semi‐IPN superabsorbent hydrogel exhibited improved swelling capability (421 g·g^?1 in distilled water and 55 g·g^?1 in 0.9 wt % NaCl solution) and swelling rate compared with CTS‐g‐PAA/PVA hydrogel (301 g·g^?1 in distilled water and 47 g·g^?1 in 0.9 wt % NaCl solution) due to the phosphorylation of PVA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Three‐layered electrospun PVA/PCL/PVA nanofibrous mats containing tetracycline hydrochloride and phenytoin sodium: A case study on sustained control release,antibacterial, and cell culture properties

The main objective of this work was to prepare a tailor‐made electrospun nanofibrous samples based on poly(?‐caprolactone) (PCL) containing tetracycline hydrochloride (TC‐HCl) as a middle layer and poly(vinyl alcohol) (PVA) including phenytoin sodium (PHT‐Na) as lateral layers. The characterizations of the three‐layered electrospun samples were carried out by using SEM, ATR‐FTIR spectroscopy along with swelling/weight loss, UV–vis spectrophotometry as well as HPLC, antibacterial and MTT tests. The SEM micrograph images showed that the average diameter of PCL nanofibers was decreased from 243 ± 7 nm to 181 ± 5 nm by adding TC‐HCl. The hydrolytic degradation of PVA nanofibers in the exposure of phosphate buffer solution (PBS) was confirmed by ATR‐FTIR results in which a change at the intensity of the characteristic peak located at 3333 cm^?1 corresponding to hydroxyl groups (? OH) was observed. The UV–vis outcomes revealed a sustained control release of TC‐HCl from the three‐layered nanofibrous samples (PVA/PCL/PVA) with an amount of about 43% compared to the PCL nanofibers which had an ultimate release of the drug about 79%. Furthermore, the HPLC chromatograms showed the released PHT‐Na from PVA nanofibers about 87%. Finally, the MTT assay along with the antibacterial evaluation exhibited that the surfaces of these electrospun three‐layered nanofibrous samples have no cytotoxicity as well as the controlled release of TC‐HCl from them enabled their prolonged use for preventing the bacterium growth such as S. aureus during 24‐h treatment time. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43309.     

Synthesis and characterization of poly(vinyl alcohol)/water glass (SiO2) nano‐hybrids via sol‐gel process

A new class of materials based on inorganic and organic species combined at a nanoscale level has received large attention recently. In this work the idea of producing hybrid materials with controllable properties is applied to obtain foams to be used as catalyst supporting. Hybrids were synthesized by reacting poly(vinyl alcohol) in acidic solution with water glass. The inorganic phase was also modified by incorporating a hexamethyldisiloxane as precursor. The hybrid aerogel powder was analyzed by scanning electron microscopy, TG‐DTA, Nitrogen adsorption–desorption, X‐ray diffraction and fourier transform infrared spectroscopy (FTIR) spectroscopy. The powder obtained had a higher porosity varying from 65 to 90% and the nanopore diameter ranged from 17 to 20 nm. The surface area and nanopore volume decreased as polymer content increased in the hybrids. The sharp decline in the weight observed at around 500°C accompanied an exothermic peak of the DTA curve. The sharp peak was observed around 211°C represents the DTA curve of Poly vinyl alcohol constituent in nano hybrids. The peak at 1638 cm^?1 in the FTIR indicated the formation of Si? O? PVA? O? Si bridge in aerogel powder. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Modeling the moisture sorption isotherms of two‐phase solid olive oil by‐product

The moisture sorption isotherms of two‐phase solid olive oil mill by‐product (SOB) were measured at different temperatures (15–50 °C) in order to thoroughly know the hygroscopic properties of this material. SOB is like a slurry with a high water content (60–70%). It is obtained in the olive oil two‐phase extraction process and is currently used as the raw material for obtaining pomace oil by extraction with hexane; prior to the extraction, drying of the SOB is required. Other uses of SOB are composting, animal feeding and solid fuel; in such cases, the previous drying of the material is also required. Sorption moisture isotherms for the two‐phase SOB were obtained by a static method. Eight models were fitted to the experimental data: BET, GAB, Halsey, Smith, Henderson, Oswin, Ferro‐Fontan and Peleg. The GAB equation was the best option to describe the water sorption behavior of SOB within a very wide range of water activities (0–0.90). A generalized GAB model, in which temperature is taken into account, was obtained by multivariable fitting of the complete set of the experimental isotherms.     

Synthesis of novel high oil‐absorption resins of poly(methyl methacrylate–butyl methacrylate) by surface‐initiated atom transfer radical polymerization using activators regenerated by electron transfer for efficient removal of oil

Oil‐absorption resins are considered one of the effective materials to separate organic chemical compounds from oily water. In this work, well‐defined high oil‐absorption resins of poly(methyl methacrylate–butyl methacrylate) grafted onto silica gel were prepared by surface‐initiated atom transfer radical polymerization using activators regenerated by electron transfer mediated by FeCl₃/iminodiacetic acid. The grafted polymers were grown in a controlled manner. By considering the effect of different polymerization conditions, we prepared novel high oil‐absorption resins. The chemical structures of the resins were determined by Fourier transform IR spectroscopy. SEM and TGA were also used to characterize the resins. It was found that the resins had good heat‐resistant quality, higher oil absorbency and better oil retention and regeneration properties. The resins can absorb 31.2 g g^?1 for tricholoromethane and 23.3 g g^?1 for toluene. Copyright © 2012 Society of Chemical Industry     

Mulberry Seed Oil: a Rich Source of δ‐Tocopherol

In the present study, mulberry seed oil (MSO) samples obtained from seeds of different mulberry varieties as well as concentrated mulberry juice production waste (mulberry pomace) were investigated. Radical scavenging capacity, tocopherol and total phenolic content of MSO were determined. It was observed that MSO contain unique amounts of δ‐tocopherol varying between 1645–2587 mg kg^?1 oil depending on the variety. The secondary tocopherol homologue was γ‐tocopherol within a concentration range of 299–854 mg kg^?1 oil. MSO exhibited a very high antioxidant capacity varying in the range of 1013–1743 and 2574–4522 mg α‐tocopherol equivalents (α‐TE) per kg of oil for 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and freeze‐dried 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) (FD‐ABTS) radical cation assays, respectively. Both antioxidant capacity and total phenolic content were higher for mulberry pomace oil compared with the seed oils. Fatty acid composition of MSO was also determined, and linoleic acid was found to be the primary fatty acid (66–80 %).     

Co‐electrospun nanofibers of PVA‐SbQ and Zein for wound healing

In this study, electrospun biocompatible nanofibers with random orientation were prepared by physically blending poly(vinyl alcohol)‐stilbazol quaternized (PVA‐SbQ) with zein in acetic acid solution for wound healing. PVA‐SbQ was used as the foundation polymer as well as crosslinking agent, blended with zein to achieve desirable properties such as improved tensile strength, surface wettability, and in vitro degradable properties. Moreover, vaccarin drug was incorporated in situ into electrospun nanofibrous membranes for cell viability and cell attachment. The addition of vaccarin showed great effects on the morphology of nanofiber and enhanced cell viability and proliferation in comparison with composite nanofibers without drug. The presence of PVA‐SbQ, zein, and vaccarin drug in the nanofibrous membranes exhibited good compatibility, hydrophilicity, and biocompatibility and created a moist environment to have potential application for wound healing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42565.     

Preparation of water‐swollen hydrogel membranes for gas separation

Water‐swollen hydrogel (WSH) membranes for gas separation were prepared by the dip‐coating of asymmetric porous polyetherimide (PEI) membrane supports with poly(vinyl alcohol) (PVA)–glutaraldehyde (GA), followed by the crosslinking of the active layer by a solution method. Crosslinked PVA/GA film of different blend compositions (PVA/GA = 1/0.04, 0.06, 0.08, 0.10, 0.12 mol %) were characterized by differential scanning calorimetry (DSC) and their water‐swelling ratio. The swelling behavior of PVA/GA films of different blend compositions was dependent on the crosslinking density and chemical functional groups created by the reaction between PVA and GA, such as the acetal group, ether linkage, and unreacted pendent aldehydes in PVA. The permeation performances of the membranes swollen by the water vapor contained in a feed gas were investigated. The behavior of gas permeation through a WSH membrane was parallel to the swelling behavior of the PVA/GA film in water. The permeation rate of carbon dioxide through the WSH membranes was 10⁵ (cm³ cm^?2 s^?1 cmHg) and a CO₂/N₂ separation factor was about 80 at room temperature. The effect of the additive (potassium bicarbonate, KHCO₃) and catalyst (sodium arsenite, NaASO₂) on the permeation of gases through these WSH membranes was also studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1785–1791, 2001     

Facile preparation and separation performances of cellulose nanofibrous membranes

Ultrafiltration (UF) is a size selective pressure‐driven membrane separation process increasingly required for high efficient water treatment and suspended solids removal in many industrial applications. This study examined the morphology of as‐prepared cellulose nanofibers and then utilized the nanofibers dispersion to fabricate nanofibrous nanoporous membranes with potential wide applications in various fields including water treatment. The nanofibers were prepared using a simple and powerful mechanical high intensity ultrasonication following a pre‐chemical treatment of α‐cellulose. The cellulose nanofibers’ morphology, crystallinity, and yield were found to be influenced by pre‐chemical treatment. Cellulose nanofibrous membranes were fabricated from cellulose nanofibers dispersion on a porous support. A nanoporous structure with an extensive interconnected network of fine cellulose nanofibers was formed on the support substrate. The resulting membranes exhibited typical and high‐efficient UF performances with high water fluxes of up to 2.75 10³ L/m²/h/bar. The membranes also displayed high rejections for ferritin and 10 nm gold nanoparticles with a reactive surface area capable of rapidly decolorizing methylene blue from its aqueous solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43544.     

Nanofibrous scaffold prepared by electrospinning of poly(vinyl alcohol)/gelatin aqueous solutions

A series of nanofibrous scaffolds were prepared by electrospinning of poly(vinyl alcohol) (PVA)/gelatin aqueous solution. PVA and gelatin was dissolved in pure water and blended in full range, then being electrospun to prepared nanofibers, followed by being crosslinked with glutaraldehyde vapor and heat treatment to form nanofibrous scaffold. Field emission scanning electron microscope (FESEM) images of the nanofibers manifested that the fiber average diameters decreased from 290 to 90 nm with the increasing of gelatin. In vitro degradation rates of the nanofibers were also correlated with the composition and physical properties of electrospinning solutions. Cytocompatibility of the scaffolds was evaluated by cells morphology and MTT assay. The FESEM images revealed that NIH 3T3 fibroblasts spread and elongated actively on the scaffolds with spindle‐like and star‐type shape. The results of cell attachment and proliferation on the nanofibrous scaffolds suggested that the cytotoxicity of all samples are grade 1 or grade 0, indicating that the material had sound biosafety as biomaterials. Compared with pure PVA and gelatin scaffolds, the hybrid ones possess improved biocompatibility and controllability. These results indicate that the PVA/gelatin nanofibrous have potential as skin scaffolds or wound dressing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Block copolymers as polymeric stabilizers in non‐aqueous emulsion polymerization

This review summarizes the background and recent advances of block copolymer stabilized oil‐in‐oil emulsions. For non‐polymerizable emulsions which have promising application possibilities for biomedical and cosmetic formulations, it is shown that tailor‐made block copolymers are by far the most efficient stabilizers with respect to low molecular weight surfactants. The characteristic features of oil‐in‐oil emulsions comprising one polymerizable phase are described. These types of non‐aqueous emulsions are of interest as nanoreactor systems for the polymerization of moisture‐sensitive monomers or catalysts. Furthermore they are the starting point of novel heterophase polymerization processes for the preparation of sterically stabilized polymer particles, as well as of ‘liquid‐filled polymeric materials’. The concept of oil‐in‐oil emulsions is finally extended to those systems where the two phases are polymerizable by distinct polymerization mechanisms. This approach could offer attractive possibilities for the development of special coatings with neither water nor solvent evaporation in their drying or curing step. Copyright © 2011 Society of Chemical Industry