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In this work, hydrophobic magnetic nanoparticles (MNPs) were successfully synthesized by the one-pot solvothermal reaction at the presence of surface modifier for the first time and characterized by SEM, EDS, TEM, WAXD, TGA, FTIR, and XPS. The fabrication of the magnetic superhydrophobic melamine sponge was realized by the deposition of the as-synthesized hydrophobic MNPs on the melamine sponge using a simple drop-coating method with the aid of silicone adhesive to achieve a firm attachment. The resultant surface-modified durable melamine sponge exhibited not only the high absorption capacities for different oil and organic solvent ranging from 39.8 g/g to 78.7 g/g but also the good reusability for absorption even after 14 absorbing-squeezing cycles. The oil absorption ability of the magnetic superhydrophobic highly-porous melamine sponge was much better than that of the magnetic superhydrophobic polyurethane sponge with relatively low porosity. Moreover, it could be found from the demonstrating experiments that the as-prepared magnetic superhydrophobic melamine sponge had the abilities to (1) remove the floating peanut oil from water followed by convenient magnetic recovery, (2) separate CH2Cl2 from water as a filter only driven by gravity, (3) absorb and collect peanut oil continuously from water surface assisted by a vacuum pump. We believe that the as-prepared magnetic superhydrophobic melamine sponge should have great potential in the effective oil-water separation.

In this paper, a magnetic graphene oxide (MGO) composite was prepared by the click reaction between the alkyne-modified Fe3O4 nanoparticles and the azide-modified graphene oxide for the purpose of removing the Congo red (CR) dye from water. The deposition of the Fe3O4 nanoparticles on the graphene oxide to successfully prepare the MGO composite was evidenced by the Fourier-transform infrared spectrometer, wide-angle X-ray diffraction equipment, scanning electron microscope, thermal gravimetric analyzer, and Raman spectrometer. The value of saturation magnetization for the MGO composite was 34.9 emu/g. The CR absorption capacities of the MGO composite increased first and then decreased as the pH value increased. It was found that the maximum adsorption capacity of the MGO composite for the CR was as high as 769.2 mg/g. In the absorption-desorption experiment, the CR absorption capacities of the MGO composite from the second cycle to the fifth cycle remained stable to be about 130 mg/g. Moreover, both the Langmuir model for the adsorption isotherm and the pseudo-second-order kinetic model could be used to describe the CR absorption behaviors of the MGO composite.

In this work, an effective method was developed to prepare novel PEO-b-PPO-b-PEO (EPE)/α-cyclodextrin (α-CD) supramolecular hydrogels containing exfoliated graphite nanoplates (xGNPs) by mi...

Fe3O4 nanoparticles were modified by tetraethoxysilane and different amounts of trimethoxy (1H,1H,2H,2H-heptadecafluorodecyl) silane in sequence to obtain the magnetic nanoparticles with low surface energy, which could be used to construct the superhydrophobic surfaces for PU sponge, cotton fabric, and filter paper by a simple drop-coating method. Particularly, all the resultant Fe3O4/PU sponges containing different fluoroalkylsilane-modified Fe3O4 nanoparticles possessed both high water repellency with contact angle in the range of 150.2–154.7° and good oil affinity, which could not only effectively remove oil from water followed by convenient magnetic recovery but also easily realize the oil-water separation as a filter only driven by gravity. The Fe3O4/PU sponges showed high absorption capability of peanut oil, pump oil, and silicone oil with the maximum absorptive capacities of 40.3, 39.3, and 46.3 g/g, respectively. Such novel sponges might be a potential candidate for oil-water separation as well as oil absorption and transportation accompanied by the advantages of simple process, remote control by magnetic field, and low energy consumption.

In this work, graphene was modified by the grafting of poly(vinylidene fluoride) (PVDF) using Friedel-Crafts reaction to form PVDF-grafted graphene (PGG) filler, which was confirmed by transmission...

A facile surface modification method of improving hydrophilicity of poly(vinylidene fluoride) (PVDF) membranes was presented by layer-by-layer assembly. Various layers of anatase TiO₂ nanoparticles were successfully deposited on electrospun PVDF fibrous membranes. FTIR, SEM, TEM and droplet scanning analysis were used to investigate microstructure and contact angle (CA) of modified membranes. TiO₂ modified PVDF fibers showed rougher surface and greater diameter compared to uncoated ones. The CA of modified membranes was significantly decreased. For instance, the CA of the 4 layers of TiO₂ modified membranes through two pretreatment methods (viz., ethanol-water displacement or KMnO₄ modification) could be decreased to 0° while the unmodified PVDF had CA of 114.4°. Moreover, the modification through ethanol-water pre-treatment formed TiO₂ coating owing to hydrogen bonds without damaging strength of PVDF. Therefore, this presents a facile and effective hydrophilic modification method for PVDF in water treatment, filtration and other fields.

Building thermal insulation can enhance the thermal environment of buildings, thus decreasing energy consumption. Traditional inorganic insulation materials are easy to absorb moisture so that their insulation performance is reduced significantly when they are used in humid environment. It is of great significance to develop new building insulation materials with low moisture absorption and high thermal insulation. In this paper, sol-gel method and ambient pressure drying were used to prepare polyester fiber felt/silica aerogel composite thermal-insulation material. The hydrophobic properties and the microstructure of the aerogel composites were characterized. Moreover, the water-vapor transmission rate and the moisture absorption rate of the aerogel composites and the fiber felt in various humidity conditions were measured. Transient thermal plane method was applied to the measurement of the thermal conductivity. The thermal conductivity and moisture absorptivity of the polyester fiber felt increased significantly with the increase of ambient humidity. After being composited with silica aerogel, both moisture absorptivity and thermal conductivity decreased significantly and kept small value even in high humidity. The moisture absorption rate of the composites is approximately 1%, and the thermal conductivity is 0.0176–0.0187 W·m−1·K−1. Therefore, the prepared fiber felt/silica aerogel composites could be widely used for building insulation even in humid areas.

Novel P(VDF-TrFE)/organosilicate composite membrane was fabricated by electrospinning. The electrospun composite membrane containing as little as 2 wt% of organosilicate demonstrated significant improvements in strength, modulus, and toughness by about 103%, 45%, and 97%, respectively, when compared with those of electrospun pure P(VDF-TrFE) membrane, while maintaining high porosity and good breathability and piezoelectricity. We believe that such an organosilicate-reinforced durable, porous, and piezoelectric P(VDF-TrFE) membrane has huge advantages in various applications such as flexible sensors, wearable electronics, filter membrane, tissue engineering, battery separator, and polymer electrolyte.

In this work, a novel Fe3O4/graphene oxide (GO) hybrid was prepared and its removal ability of cationic methylene blue dye from water was investigated. To improve the dispersability of Fe3O4/GO hybrid in water, GO was first modified by polyethylene glycol (PEG) via a click approach before deposition of Fe3O4 nanoparticles onto its surface. The successful modification of GO surface and the deposition of Fe3O4 nanoparticles were confirmed by transmission electron microscopy directly. The saturation magnetization of the resultant Fe3O4/GO hybrid is 7.8 eum/g. The adsorption capacities of Fe3O4/GO hybrid for methylene blue at 35 and 60°C were as high as 96.05 and 120.05 mg/g, respectively. Moreover, the Langmuir, Freundlich, and Temkin models are used to investigate the isothermal adsorption behavior of Fe3O4/GO hybrid.

Understanding the effect of a porous TiO2 nanolayer on the optical scattering and absorption through electrospun fibers is of great importance for the design and development of advanced optical extinction materials. Based on electrospinning and controllable self-assembly techniques, pure electrospun poly(vinylidene fluoride) (PVDF) fibers and TiO2-coated ones with different self-assembly cycles were prepared. The effect of TiO2 self-assembly cycles on surface parameters, e.g., thickness, assembled content, and porosity of the TiO2 nanolayer were determined by scanning electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. With an increase in the self-assembly cycles, the TiO2-coated electrospun PVDF fibers presented rougher surfaces and greater average diameters. According to the characterized surface parameters, the effects of the controllable self-assembly on the optical refractive index, absorption index, and infrared extinction were investigated to increase the optical properties of electrospun PVDF fibers. The results indicated that an increase of almost 120&ndash, 130 cm&minus, 1 in infrared extinction could be achieved through the controllable self-assembly with only 5.7 wt. % assembled TiO2 content. This is highly efficient when compared with other coating modes. We believe that this study could give some positive guidance in the design of TiO2-coated electrospun fibers for improving their surface and optical properties.

Nanofibrous silver (Ag)/poly(vinylidene fluoride) (PVDF) composite membranes were obtained from a two-step preparation method. In the first step, the electrospun silver nitrate (AgNO3)/PVDF membranes were prepared and the influence of the AgNO3 content on the electrospinning process was studied. According to scanning electron microscopy (SEM) results, when the electrospinning solution contained AgNO3 in the range between 3 to 7 wt.%, the nanofiber morphologies can be obtained. In the second step, the electrospun AgNO3/PVDF membranes were reduced by sodium borohydride to form the nanofibrous Ag/PVDF composite membranes. The resultant composite membranes were characterized by SEM, X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), differential scanning calorimetry, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared. The XRD, XPS, and EDS characterizations proved the existence of Ag in the nanofibrous Ag/PVDF composite membranes. The crystallinity degree of PVDF for composite membranes declined with the increase in Ag content. More importantly, the nanofibrous Ag/PVDF composite membranes had obviously higher Rosseland extinction coefficients and lower thermal radiative conductivities in comparison with electrospun PVDF membrane, which demonstrates that such composite membranes with high porosity, low density, and good water vapor permeability are promising thermal insulating materials to block the heat transfer resulting from thermal radiation. In addition, three different methods for surface modification have been used to successfully improve the hydrophobicity of nanofibrous Ag/PVDF composite membranes.

Novel exfoliated graphite nanoplates (xGNPs)/syndiotactic polystyrene (sPS) composites were prepared by a simple and effective solution-blending method. The uniform dispersion of xGNPs in sPS matrix was confirmed by scanning electron microscopy. The effect of xGNPs on sPS crystallization behavior was investigated by wide angle X-ray diffraction and differential scanning calorimetry. It was found that the existence of xGNPs increased the crystallization ability of sPS and facilitated the formation of the β phase crystalline structure. By adding 10 wt.% of xGNPs, the increase in the onset degradation temperature of the xGNPs/sPS composite could reach 12°C. The AC electrical conductivity at 1000 Hz increased from 3.8 × 10 −10 S/m for neat sPS to 2.25 × 10 −4 S/m for xGNPs/sPS composite containing 2.93 vol.% of xGNPs. Moreover, the thermal conductivity of the xGNPs/sPS composite containing 8.26 vol.% has been significantly improved from 0.21 to 1.63 W/m·K when compared with that of pure sPS.

The microphase separation of amphiphilic dendrimer copolymers in a selective solvent with different excluded volume effects (αS) is investigated using three-dimensional real space self-consistent field theory. The morphological transition of disorder-to-order and order-to-order is observed by systematically regulating the excluded volume effect parameter, interaction parameter of block species, and the spacer length of the second generation of the dendrimer. The ordered segregates of the dendrimer solution are observed with a stronger excluded volume effect due to the strong depletion effect of solvent on the dendrimer. The relative magnitude between hydrophobic block B and hydrophilic block C is very important for microphase separation: when they are equal (NB = NC), a structural shift from vesicles to micelles has been found upon increasing the interaction parameter, and the region of disordered morphology is controlled by the interfacial free energy (Uint); when NB > NC, the vesicular morphologies overwhelmingly appear in the ordered region and then NC increases to close to NB, and the ordered aggregates take a shift from vesicles to micelles. Furthermore, the amphiphilic block C of the dendrimer is intended to enlarge to NC > NB, the micellar morphology is dominant in the ordered regime with a stronger excluded volume effect, which contributes to the decrease in the hydrophobic block repulsion that is affected by the decrease in the entropic free energy (−TS). The knowledge obtained from the microphase separation of dendrimer solution induced by the excluded volume effect of selective solvent is full of referential significance in understanding the morphological transition from vesicles to micelles for the amphiphile in the field of soft matter.

Exfoliated graphite nanoplates (xGNPs) were chemically functionalized by the 1,3 dipolar cycloaddition reaction of azomethine ylides. The introduction of organic groups on the external graphitic layers of xGNPs was confirmed by Fourier-transform infrared spectroscope, scanning electron microscope, transmission electron microscope, and thermal gravimetric analyzer. The resultant functionalized xGNPs (f-xGNPs) could be suspended in N-methyl-2-pyrrolidinone after ultrasonic treatment, which facilitated their homogeneous dispersion in syndiotactic polystyrene (sPS) matrix to form f-xGNPs/sPS composites by a solution-blending method. It was found that the existence of f-xGNPs increased the crystallization temperature but reduced the crystallization degree of sPS due to their strong interfacial interaction with sPS matrix. The dependences of electrical and dielectric properties of f-xGNPs/sPS composites on concentration of f-xGNPs and frequency were investigated. When the concentration of f-xGNPs is 10 wt.%, the electrical conductivity and the dielectric constant of f-xGNPs/sPS composites were 1.5 × 10−7 S/m and 36.4 at 1000 Hz, respectively, while the corresponding values of sPS were 3.8 × 10−10 S/m and 2.83, respectively. The enhanced and stable dielectric constant of f-xGNPs/sPS composites could be ascribed to the well dispersion of f-xGNPs in sPS matrix, resulting in the formation of a large number of microcapacitors.

Spirulina–poly(vinyl alcohol) (PVA)–glycerol (SPG) films with improved mechanical performance, especially tensile strength (TS) and the elongation at break (EAB), are fabricated by a casting method. The integrity, color, solubility, microstructure, thermal properties, tensile strength, and compatibility of the SPG films are assessed. SPG films became smooth, homogeneous, and flexible after plasticizing with glycerol. The presence of PVA and hydrogen bonding of PVA with glycerol and spirulina protein improves the water resistance of SPG films by decreasing water absorption of spirulina protein and decreasing water diffusion through the films. The amount of carbonaceous residues decreases from 31% to 14% because of the co-pyrolysis of spirulina, PVA, and glycerol. TS increases from 2.5 to 26 Mpa and modulus from 53 to 610 Mpa with increasing PVA content. Glycerol enhances film flexibility and EAB up to 50%. Spirulina can be composited with hydrophilic polymers to fabricate compatible, processable and thermally recyclable films with desirable mechanical performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44842.

In this work, nanofibrous poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) membranes with different PMMA contents from 10 wt% to 20 wt% were prepared by electrospinning. The morphology of resultant membranes was investigated using scanning electron microscopy. It was found that the morphology of PVDF/PMMA electrospun nanofibers in the membrane was highly dependent on the solvent used during the electrospinning process. PVDF/PMMA nanofibers with beads were formed in the electrospun membrane when N, N-dimethylformamide (DMF) solvent was used due to its low evaporation rate. Uniform PVDF/PMMA nanofibers without beads in the electrospun membranes were obtained by DMF–acetone mixed solvent. The crystallization behavior of PVDF in the electrospun PVDF/PMMA membranes was investigated using differential scanning calorimetry and Fourier transform infrared spectroscopy. The β form crystalline structure was the major crystalline phase of PVDF in electrospun PVDF/PMMA membranes, and PMMA may suppress the formation of α crystalline phase of PVDF. The crystallinity degree of PVDF in the electrospun PVDF/PMMA membranes was lower than that of the electrospun PVDF membrane, and the annealing could effectively improve the crystallinity degree of PVDF in electrospun membranes. Moreover, it was found that the annealing has no adverse effect on the low density, high porosity, and water vapor permeability of electrospun membranes.

A allyl-substituted salicylaldimine proligand ( Scheme 1 , Compound 5) was prepared by a condensation reaction, which reacted with trans-[NiCl(Ph)(PPh3)2] to give a binuclear neutral nickel (II) complex [((4-Allyl-2,6-iPr2C6H2) NCH)C6H3ONi(PPh3)Ph]2 ( Scheme 1 , Complex 6). The structure of the complex was characterized by 1H NMR, 13C NMR and elemental analysis. This novel complex bearing allyl groups can be used as a self-immobilizing catalyst for the polymerization of ethylene and does not need a cocatalyst for their catalytic performance. The self-immobilizing catalytic systems not only possess high activity (up to 5.23 × 105 g of PE/(mol of Ni h)) but also can produce high-molecular-weight polyethylenes (Mw = (0.42–0.71) × 106) with relatively broad molecular weight distributions (MWD = 2.83–3.11). According to the 13C NMR analyses, the resultant polyethylenes contain a few branched chains mainly consisting of methyl branches.

Graphene nanosheet–Fe 3 O 4 (GNS–Fe 3 O 4 ) hybrids were obtained by a one-step solvothermal reduction of iron (III) acetylacetonate [Fe(acac) 3 ] and graphene oxide (GO) simultaneously, which had several advantages: (1) the Fe 3 O 4 nanoparticles were firmly anchored on GNS surface even after mild ultrasonication; (2) the loading amount of Fe 3 O 4 nanoparticles could be effectively controlled by changing the initial feeding weight ratio of Fe(acac) 3 to GO; (3) the Fe 3 O 4 nanoparticles were homogeneously distributed on the GNS surface without much aggregation. Composites based on syndiotactic polystyrene (sPS) and GNS–Fe 3 O 4 were prepared by a solution-blending method and the electric and dielectric properties of the resultant GNS–Fe 3 O 4 /sPS composites were investigated. The percolation threshold of GNS–Fe 3 O 4 in the sPS matrix was determined to be 9.41 vol.%. Slightly above the percolation threshold with 9.59 vol.% of GNS–Fe 3 O 4 , the GNS–Fe 3 O 4 /sPS composite showed a high dielectric permittivity of 123 at 1000 Hz, which was 42 times higher than that of pure sPS. The AC electrical conductivity at 1000 Hz increased from 3.6 × 10 −10 S/m for pure sPS to 2.82 × 10 −4 S/m for GNS–Fe 3 O 4 /sPS composite containing 10.69 vol.% of GNS–Fe 3 O 4 , showing an obvious insulator-semiconductor transition.

Ferroelectric polymers, including polyvinylidene fluoride homopolymer and poly(vinylidene fluoride-trifluoroethylene) [P(VDF–TrFE)] copolymer, have been investigated extensively due to their potential application in sensors, actuators, transducers and energy harvesting. Recently, porous ferroelectric polymers have stimulated much interest because such materials have advantages of light weight, low acoustic and mechanical impedance, and high voltage sensitivity. In this work, P(VDF-TrFE) porous membranes were prepared for the first time by electrospinning and subsequent hot pressing. The morphology of the resultant electrospun membranes (nanofibers with or without beads) can be varied depending on the concentration of polymer solution used during the electrospinning process. Differential scanning calorimetry, wide-angle X-ray diffraction and Fourier-transform infrared confirmed the automatic formation of β crystallites in the P(VDF-TrFE) electrospun porous membrane. Based on piezoelectric strain coefficient measurement, dielectric constant measurement and dynamic mechanical analysis, it was found that the hot pressed P(VDF-TrFE) electrospun membrane with beads not only had a relatively high d33 value compared with those of other electrospun P(VDF-TrFE) membranes, but also the advantage of low dielectric constant and high flexibility.

Hybrids of graphene oxide (GO) nanosheets and surface-modified Fe 3 O 4 nanoparticles (NPs) were fabricated by a two-step process. First, Fe 3 O 4 was modified by tetraethyl orthosilicate and (3-aminopropyl) triethoxysilane to introduce amino groups on its surface. Second, the amino groups of Fe 3 O 4 were reacted with the carboxylic groups of GO with the aid of 1-ethyl-3-(3-dimethyaminopropyl)carbodiimide and N -hydroxysuccinnimide to form a GO–Fe 3 O 4 hybrid. The attachment of Fe 3 O 4 NPs on the GO nanosheet surface was confirmed by transmission electron microscopy and Fourier-transform infrared spectroscopy. The adsorption capacity of GO–Fe 3 O 4 for methylene blue and neutral red cationic dyes was as high as 190.14 and 140.79 mg/g, respectively. The GO–Fe 3 O 4 hybrids could be reduced to form graphene–Fe 3 O 4 hybrids by using NaBH 4 as reducing agent and be used to prepare magnetic GO films.

Nanocomposites based on poly(vinylidene fluoride) (PVDF) and exfoliated graphite nanoplate (xGnP) were prepared by solution precipitation method. The resulting nanocomposites were investigated with respect to their structure and properties by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), wide-angle X-ray diffraction, and dynamic mechanical analysis. Both SEM and TEM examinations confirmed the good dispersion of xGnP in the PVDF matrix. The nonisothermal crystallization behavior of the PVDF/xGnP nanocomposites was studied using DSC technique at various cooling rates. The results indicated that the xGnPs in nanometer size might act as nucleating agents and accelerated the overall nonisothermal crystallization process. Meanwhile, the incorporation of xGnP significantly improved the storage modulus of the PVDF/xGnP nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Here we have developed cellulosic materials (cotton fabric or paper) with differential superhydrophobicity and hydrophilicity on each side of the surfaces by coating with polyvinylidene fluoride and fluorinated silane molecules using electro-spraying. Such materials are advantageous in various textile and medical applications. Analysis of surface morphology indicated that, not only surface chemical property and roughness, but also particle diameter affects surface superhydrophobicity. Smaller particle diameter enhances superhydrophobicity, if the surface roughness and surface chemical property remain constant. By controlling these three factors, superhydrophobicity with a water contact angle of more than 160° can be achieved at one side of a thin cellulosic material while maintaining the hydrophilicity (contact angle is 0°) at the opposite side.

Moisture-responsive fabrics have great potential in the development of smart clothing which can respond to changes in the physiological conditions of the wearer and environmental conditions so as to achieve maximum comfort. In this research, the reversible dimensional changes of hygroscopic yarns are utilized to develop responsive fabric structures which widen or narrow their openings depending on moisture content. Experiments showed that these novel fabrics exhibited improved air permeability at higher moisture content, which may be associated with body sweating or a hot, humid climate. The improved air permeability can enhance body cooling for better comfort.

Poly(vinylidene fluoride) (PVDF)/graphite composites were prepared by a solution precipitation method for the first time. The mechanical, thermal and dielectric properties of these composites were studied by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and an impedance analyzer, respectively. The results indicated that graphite content has a significant effect on the crystallization behavior of the PVDF. The storage modulus and the dielectric constant of the composites increased linearly with graphite concentration. When the graphite loading amount was 10 wt%, the storage modulus at 20 °C and the dielectric constant at 10 4 Hz were approximately 83% and 93% higher than those of pure PVDF, respectively.

Poly(vinylidene fluoride) (PVDF)/exfoliated graphite nanoplate (xGnP) nanocomposites were prepared by a solution mixing method for the first time. The thermal, mechanical and electric properties of these nanocomposites were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and an impedance analyzer, respectively. The DSC results indicated that xGnP might act as the nucleating agents and accelerated the overall non-isothermal crystallization process of PVDF. Meanwhile, the incorporation of xGnP also significantly improved the storage modulus and conductivity of the PVDF/xGnP nanocomposites with an increment in the graphite nanoplate content, respectively.

In this work, we developed two novel strategies to attach metal nanoparticles (Au and Ag) to the surface of graphene nanosheets, in which graphene oxide was first modified by the linking molecule (3-mercaptopropyl)triethoxysilane and then subjected to different treatments including in situ and self-assembled techniques. The synthesis processes and the resulting hybrids were investigated by ultraviolet-visible measurements, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was found that both approaches could effectively immobilize metal nanoparticles onto a graphene surface, and that better distribution and size control of metal nanoparticles were obtained by the self-assembled method. Moreover, we prepared poly(vinylidene fluoride)/graphene-Ag nanocomposites by a solution blending method. The AC conductivity of the resulting nanocomposites could be increased significantly when the loading amount of graphene-Ag was only 2 wt%. We expect that such graphene-metal nanoparticle hybrids may be potentially useful in composite reinforcement, sensors, and electronic devices.