Fabrication and characterization of novel nanofibers from cress seed mucilage for food applications

Cress seed mucilage (CSM) as a new source of biomacromolecule has gained attraction in food science due to its biodegradability and biocompatibility. In this research CSM–poly(vinyl alcohol) (PVA) nanofibers were produced under different conditions by electrospinning technique. Viscosity and electrical conductivity of the produced biopolymers were analyzed. The effect of CSM to PVA volume ratio and applied electrical field were evaluated on nanofiber morphology by scanning electron spectroscopy. The optimum nanofibers showed smooth and uniform surfaces with diameter size range of 95–278 nm. The results of Fourier transform infrared spectroscopy of CSM–PVA nanofiber with volume ratio of 60:40 showed characteristic peaks of CSM and PVA. X‐ray diffractometer data clearly revealed the amorphous structure of the electrospun nanofibers. Thermogravimetric and derivative thermogravimetric analysis indicated that thermal stability of electrospun nanofibers increased in comparison to CSM and PVA. The results of this study indicated that CSM can be applied as a new source of biopolymer for production of nanofibers that could be used for different applications such as delivery systems and packaging film fabrication. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45811.     

Electrospinning of flux‐enhanced chitosan–poly(lactic acid) nanofiber mats as a versatile platform for oil–water separation

Environmentally friendly chitosan (CS)–poly(lactic acid) (PLA) nanofiber mats were designed and constructed by an electrospinning strategy. Studies on the wettability of the CS–PLA nanofiber mats showed that they possessed excellent hydrophobic and oleophilic properties in the pH range 1–12. A layered oil–water mixture was separated by CS–PLA nanofiber mats, and the oil flux of the mats collected by #10 stainless steel wire mesh (sample P‐10) was up to 511.36 L m^?2 h^?1, which was approximately 25 times higher than that of the mats collected by #0 stainless steel wire meshes (sample P‐N). The superior properties of the CS–PLA nanofiber mats may have been due to their tunable porous structure and fine flexibility. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45830.     

A biaxial stretched β‐isotactic polypropylene microporous membrane for lithium‐ion batteries

In this article, microporous polypropylene (PP) membranes were produced with TMB‐5 as β‐crystal nucleating agent by biaxial stretching. Influences of different concentration of TMB‐5 were studied using differential scanning calorimetry and X‐ray diffraction. It was found that the highest crystallinity was reached when the nucleating agent content was 0.5 wt %. The effect of stretching temperature and stretching ratio on pore size distribution and porosity of the membranes were investigated by scanning electron microscopy and mercury porosimeter, respectively. And physical properties, such as tensile strength, permeability, and puncture resistance of the microporous membrane prepared at the optimized conditions, were evaluated. Compared with commercial PP separator membrane, the as‐prepared microporous membrane shows similar uniform pore size distribution and exhibits slightly higher porosity and ionic conductivities. When used as lithium‐ion separator, the experimental film shows more stable cycling performance than the commercial one. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45825.     

Dextran microgels loaded with ZnO QDs: pH‐triggered degradation under acidic conditions

We demonstrated an extremely facile way to fabricate inorganic–organic microgels with pH sensitivity and fluorescence. Aqueous dextran microgels are crosslinked by ZnO quantum dots (QDs). The ZnO@Dextran microgels were synthesized by simply mixing amino‐modified ZnO (ZnO QDs) with carboxymethyl dextran (CMD) while stirring. The hybrid microgels showed an average diameter of ～5 μm and strong fluorescence under ultraviolet (365 nm) irradiation. Up to 79.3 wt % of ZnO QDs were loaded into microgels. The ZnO QDs crosslinkage in the hybrid microgels structure enabled the microgels to degrade under mild acidic environment due to pH sensitivity of ZnO QDs. After loading of doxorubicin (Dox), the microgels were used as drug carriers for pH‐controlled release of Dox. The degradation of the microgels and the release of loaded cargos could be monitored by detecting fluorescence intensity of the microgels. Moreover, owing to the cytotoxicity of ZnO QDs at their destination, drug‐loaded ZnO@Dextran microgels can be used for synergistic therapy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45831.     

Synthesis and characterization of modified poly(aspartic acid) and its performance as a formaldehyde adsorbent

A modified poly(aspartic acid) (PASPTU) as an efficient formaldehyde adsorbent is successfully prepared by grafting poly(aspartic acid) (PASP) with threonine and urea. The graft copolymer is characterized by means of nuclear magnetic resonance, Fourier transform infrared spectroscopy, and gel permeation chromatography. Its formaldehyde adsorbent property is measured. The optimal adsorption process is as follows: synthesis temperature was 40 °C, molar ratio of PSI, threonine, and urea was 1:0.6:0.4 and adsorption time was 3.0 h. In above condition, the formaldehyde adsorbent efficiency of the copolymer was nearly 100% when the PASPTU dosage was 0.5 g. The Langmuir and Freundlich adsorption isotherms are used to study the adsorption process of formaldehyde. The findings show that PASPTU has excellent formaldehyde adsorbent efficiency. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45798.     

Electrospinning of polycaprolactone nanofibers using H2O as benign additive in polycaprolactone/glacial acetic acid solution

Considerable efforts have been devoted to the production of polycaprolactone (PCL) nanofibrous structures by electrospinning. However, some toxic solvents have often been used to achieve bead‐free nanofibers. At present, a benign solvent such as glacial acetic acid (GAC) only leads to beaded or microscale fibers. Therefore a study is done to extend the electrospinnability of the PCL/GAC system by the addition of H₂O. The solution properties of conductivity, viscosity, and surface tension were altered by the addition of H₂O, especially increasing the conductivity and viscosity. These properties essential to electrospinning could remain stable for 6 h when the H₂O content was less than or equal to 9 vol %. Then ultrafine PCL fibers with diameters from 188 to 200 nm, 10 times smaller than when dissolved in pure GAC, were electrospun from solutions of PCL with concentrations in the range of 17 to 20 wt % with H₂O content at 9 vol %. Finally, the crystallinity and crystallite size of the resulting fibers were smaller than that of raw PCL pellets. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45578.     

Recent progress in electrospinning TiO2 nanostructured photo‐anode of dye‐sensitized solar cells

The key to improving the performance of dye‐sensitized solar cells is the photo‐anode that has much dye adsorption and short optoelectronic transmission path. Electrospun TiO₂ films in photo‐anode have high specific surface area and meet the demand exactly. The article summarizes these efforts in TiO₂ photo‐anode improvement, including various morphology, different one‐dimensional and two‐dimensional composite structure, and varied element doped TiO₂ photo‐anode. Besides, the review makes comparison with these different TiO₂ photo‐anodes in photoelectric properties. The conclusions provide a clear guidance in design of morphology, structure, and doping, which is helpful for researcher to improve the performance of the anode and increase the photoelectric conversion efficiency especially those prepared using electrospinning. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45649.     

Effect of hybrid hollow microspheres on thermal insulation performance and mechanical properties of silicone rubber composites

Hollow microspheres (HM) of ceramic, silica, and glass‐filled silicone rubber (SR) composites were prepared, and the effects of hybrid HM on thermal and mechanical properties of composites were investigated. The results indicate that hybrid HM can effectively improve the thermal insulation property of HM/SR composites. Especially, for sample 15S, the thermal conductivity and thermal degradation temperature reached 0.1273 W/m K and 521 °C (45 °C higher than that of neat SR), respectively. Besides, thermal insulation performance was improved, showing as a temperature of 103.2 °C after 15 min heating, which is 37.8 °C lower than that of SR. The tensile strength of composites was enhanced from 1.92 MPa at 11.56 vol % hollow silica microspheres (HSM) loading to 3.08 MPa at 21.88 vol % HSM loading. Moreover, the compressive strength was improved from 3.33 to 5.68 MPa by introducing more hollow ceramic microspheres into the matrix, in this case, from 7.79 to 15.33 vol %. Furthermore, the failure mechanism was analyzed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46025.     

Decorated‐magnetic‐nanoparticle‐supported bromine as a recyclable catalyst for the oxidation of sulfides

Herein, we present a strategy for supporting bromine as a catalyst for the oxidation of sulfides. In this strategy, branched poly(ethylene imine) was first decorated by magnetic oxide and then used to support liquid bromine to obtain solid polymeric bromine (M@PEI@Br) nanoparticles. Compared with free bromine, the stability of the M@PEI@Br nanoparticles improved obviously. The oxidation of thioanisole to methyl phenyl sulfoxide was chosen as a reaction model to evaluate the catalytic activity of the M@PEI@Br nanoparticles. All of the obtained results verify that the M@PEI@Br nanoparticles exhibited excellent catalytic efficiency and could accelerate the oxidation process under solvent‐free conditions at room temperature; this highlighted the potential of decorated polymers to support active and unstable small‐molecule organic catalysts. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46036.     

Benign route for the modification and characterization of poly(lactic acid) (PLA) scaffolds for medicinal application

Scaffolds fabricated from polymers have imprinted its wide applicability in the field of tissue engineering. The surface of electrospun poly(lactic acid) (PLA) nanofibers was modified to improve their compatibility with living medium. PLA film were treated with alkali solution to introduce carboxyl groups on the surface followed by covalent grafting of gelatin using Xtal Fluoro‐E as coupling agent. The gelatin g‐PLA polymer synthesized via ‘graft‐onto’ method exhibit fascinating properties as studied by contact angle measurement, fourier transformed infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, water vapor transmission rate(WVTR), swelling studies and differential scanning calorimetry. The fabricated gelatin g‐PLA scaffolds were further characterized to conduct the study on hydrolytic degradation, and extent of biodegradation at ambient temperature. It was observed from the in‐vitro analysis that the gelatin g‐PLA nanofiber (with hemolytic percentage, 0.56 ± 0.13%) was cytocompatible with fibroblast cell and does not impair cell growth. The WVTR obtained for the electrospun mat around 2900 ± 100 g/m². 24 h signifies the optimal moist environment required for tissue engineering especially wound healing. Notably, many of these strategies resulted in porous hydrophilic scaffolds with human cell growth and proliferation for medical applications of various types. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46056.