Preparation and properties of silver‐containing nylon 6 nanofibers formed by electrospinning

Nylon 6 nanofibers containing silver nanoparticles (nylon 6/silver) were successfully prepared by electrospinning. The structure and properties of the electrospun fibers were studied with the aid of scanning electron microscopy, transmission electron microscopy, energy‐dispersive spectroscopy, and X‐ray diffraction. The structural analysis indicated that the fibers electrospun at maximum conditions were straight and that silver nanoparticles were distributed in the fibers. Finally, the antibacterial activities of the nylon 6/silver nanofiber mats were investigated in a broth dilution test against Staphylococcus aureus (Gram‐positive) and Klebsiella pneumoniae (Gram‐negative) bacteria. It was revealed that nylon 6/silver possessed excellent antibacterial properties and an inhibitory effect on the growth of S. aureus and K. pneumoniae. On the contrary, nylon 6 fibers without silver nanoparticles did not show any such antibacterial activity. Therefore, electrospun nylon 6/silver nanocomposites could be used in water filters, wound dressings, or antiadhesion membranes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

原位乳液聚合聚苯胺/聚甲基丙烯酸甲酯复合物及其表征

以DBSA为乳化剂和掺杂剂,在水介质中采用原位乳液聚合法制备出了聚苯胺/聚甲基丙烯酸甲酯(PANI/PMMA)复合物。采用扫描电镜、红外光谱分析、紫外光谱分析、热失重分析、X射线光电子能谱分析对PANI/PMMA复合物进行了表征。结果表明:复合物产物粒径在80～120nm;电导率可达到10-2S/cm,接近于乳液聚合得到的DBSA掺杂态PANI;乳化剂DBSA以掺杂剂和稳定剂两种状态存在于复合物中。     

Preparation and characterization of conductive poly(vinyl alcohol)/polyaniline doped by dodecyl benzene sulfonic acid (PVA/PANDB) blend films

In this study a solution‐blend method is adopted to prepare conductive poly(vinyl alcohol)/polyaniline doped by dodecyl benzene sulfonic acid (PVA/PANDB) blend films. Emeraldine base (EB)‐type polyaniline (PANI) is dissolved in N‐methyl‐2‐pyrrolidinone (NMP) and then blended with PVA/dodecyl benzene sulfonic acid (DBSA) solution by various amounts. It is found that the electrical conductivity and the thermal degradation onset temperature of the PVA/PANDB blend film are increased as the amount of EB‐type PANI solution is increased. Fourier transform infrared (FTIR) spectra show that the intensity of the characteristic peak of the functional groups in the blend film is significantly changed as the amount of EB‐type PANI is changed. From optical microscopy examination, it indicates that the amount and size of green particles are increased with increasing the amount of EB‐type PANI solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3415–3422, 2007     

Improved surface characteristics and the conductivity of polyaniline–nylon 6 fabrics by plasma treatment

The effect of plasma treatment on the surface characteristics and conductivity of polyaniline–nylon 6 composite fabrics was investigated. Plasma surface modifications with oxygen, ammonia, and argon were performed on the nylon 6 fabrics to improve the adhesion and rate of polymerization. The surface morphology of the fiber was observed with scanning electron microscopy, and functional groups introduced onto the surface of nylon 6 fibers by various plasma treatments were characterized by X‐ray photoelectron spectroscopy. With oxygen plasma treatment, the fiber surface was effectively etched; polar groups such as ? OH and ? OOH were introduced onto the surface of nylon 6 fiber, and they increased surface activity, promoted oxidation polymerization, and resulted in higher add‐on and electrical conductivity. However, the introduced amine and amide groups with ammonia treatment caused a reduction in conductivity. Argon did not significantly alter the surface characteristics of the nylon 6 fibers. In addition, to control fabric conductivity and cover as wide a range of conductivity as possible, we observed the effects of the monomer concentration and number of deposits on the fabric conductivity. The results showed that fabric conductivity increased as the monomer concentration increased up to 0.5M and then leveled off, and further increases were achieved with an increase in the number of multiple deposits. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 684–694, 2001     

High‐flow nylon 6 by in situ polymerization: Synthesis and characterization

A new synthetic strategy for high‐flow nylon 6 was developed in this article. Generation 1, 2, 3 (G1, G2, G3) polyamidoamine (PAMAM) dendrimers reacted with p‐phthalic acid by equimolar terminal groups in water solution, respectively, and mother salt solution was then prepared. The high‐flow nylon 6 was prepared with suitable quantity of mother salt solution, end‐capping agent, and ?‐caprolactam by in situ polymerization. Blue shifts are found for the peaks of NH (γN? H and 2δN? H) of the high‐flow nylon 6 compared with pure nylon 6 in the IR spectra. Comparing with the pure nylon 6, the high‐flow nylon 6 containing low content of PAMAM units, has high‐flow property and almost the same mechanical property. The high‐flow nylon 6 with low content of PAMAM units has greater melt‐flow index (MFI) (the value of MFI increased by 70–90%). Hardly any decrease in the tensile strength is observed with the elongation at break decreasing by 20–35%. But the izod impact strength of the high‐flow nylon 6 increases. The SEM images show that the high‐flow nylon 6 presents brittle fracture with conglomeration‐like structure, while pure nylon 6 exhibits plastic fracture with island‐like structure. DSC thermograms of nonisothermal crystallization exhibit that the peak of high‐flow nylon 6 broadens compared with pure nylon 6, and the broader peak means the wider processing temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Toughening and phase separation behavior of nylon 6–PEG block copolymers and in situ nylon 6–PEG blend via in situ anionic polymerization

We have prepared in situ molded products of morphologically different nylon 6/polyethylene glycol (PEG) copolymers and their blends via anionic polymerization of ε-caprolactam in the presence of several kinds of PEG derivatives using sodium caprolactamate as a catalyst and carbamoyl caprolactam derivative as an initiator. Three carbamoyl caprolactams, such as tolylene dicarbamoyl dicaprolactam (TDC), hexamethylene dicarbamoyl dicaprolactam (HDC), and cyclohexyl carbamoyl caprolactam (CCC), with different functionalities and activities were used. Phase separation behavior was investigated by dynamic mechanical thermal analysis (DMTA) and DSC during in situ polymerization and melt crystallization. The mechanical properties of these molded products were evaluated. PEG segments in the block copolymers showed amorphous characteristics, whereas a large fraction of unreacted PEG segments was crystallized in as-polymerized samples, except for the products obtained using the CCC activator. The presence of PEG derivatives retarded the crystallization of nylon 6 part during in situ polymerization as well as melt crystallization. However, PEG segments did not alter the crystalline structure of nylon 6, showing α-crystalline modification. The nylon 6–PEG–nylon 6 triblock copolymers showed the highest impact strength, whereas the nylon 6–PEG diblock copolymers and in situ nylon 6–PEG blends showed no improved toughness. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1285–1303, 1999     

Spinning speed–throughput rate relationships for polyester,nylon, and polypropylene fibers

The relationship between spinning speed and throughput rate has been investigated for fibers having the same fiber denier in the drawn state when produced by melt spinning of poly(ethylene terephthalate), nylon 6, and polypropylene polymers over a range of take-up speed (750–3000 m min^-1) and throughput rate. To understand the structural origin of the relationship, a limited amount of characterization of structure and properties of the as-spun and drawn fibers was also done. A comparison of the results for the three polymers shows that while the increase in productivity with increase in spinning speed is relatively less for polyester and nylon 6, it is quite high for polypropylene. The birefringence data show that while molecular orientation increases rapidly with increasing wind-up speed in polyester and nylon 6, the rate of increase is relatively less in the case of polypropylene. The possible reasons for the observed differences in behavior are discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1773–1788, 1997     

Preparation and properties of antibacterial,biocompatible core–shell fibers produced by coaxial electrospinning

Coaxial electrospinning is a method for producing fibrous mats with optional features, such as antibacterial properties, controllable release, and hydrophobicity based on shell materials. Because these features are important in biomedical applications, in this study, biocompatible hydrophobic polymer (polycaprolactone) and hydrophilic polymer [poly(vinyl alcohol)] with silver nanoparticles loaded in the core solution were coaxially electrospun. The effect of silver addition on the conductivity and viscosity of the solutions, chemical structure of the fiber mats, mechanical properties, porosity, hydrophobicity, water vapor transmission rate (WVTR), silver release, and antibacterial properties were investigated. Fibers with silver exhibited less porosity and a lower WVTR and a greater contact angle than the fibers without silver. Furthermore, the core–shell fibers reduced the burst release of silver and successfully prevented the growth of Escherichia coli and Staphylococcus aureus bacteria. Therefore, it seems that these fibers are suitable for providing electrospun mats with long‐term antibacterial properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44979.     

Characterization and anticorrosive properties of poly(2,3‐dimethylaniline)/Na+‐montmorillonite composite prepared by emulsion polymerization

Composites of Poly(2,3‐dimethylaniline) and inorganic Na⁺‐montmorillonite clay were synthesized by emulsion polymerization. The as‐synthesized composites (PDMA) were characterized by Fourier Transform Infrared Spectroscopy, X‐ray diffraction, and scanning electron microscopy. The protective performance against corrosion of the samples was evaluated by Tafel and electrochemical impedance spectroscopy measurements. The results showed that the composite containing 5 wt. % of clay loading (PDMA‐5%) displayed a better anticorrosive performance than other samples. The Epoxy(E) blend with PDMA‐5% (EPM5) coating was founded to have a higher corrosion potential and a lower current density than that of Epoxy blend P(2,3‐DMA) (EP) coating. The impedance value of EPM5 coating was about 6.68×10⁶Ω·cm² in 5 wt. % NaCl solution even after 288 h, compared to EP (4.26×10⁵Ω·cm²) coating, which went to show that the corrosion inhibition of P(2,3‐DMA) could be effectively enhanced by incorporating MMT into the P(2,3‐DMA) matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4528–4533, 2013     

Preparation and properties of electrically conducting textiles by in situ polymerization of poly(3,4‐ethylenedioxythiophene)

Poly(3,4‐ethylenedioxythiophene) (PEDOT) was in situ polymerized on nylon 6, poly(ethylene terephthalate) (PET), and poly(trimethylene terephthalate) (PTT) fabrics using ferric p‐toluenesulfonic acid (FepTS) and ferric chloride (FeCl₃) as oxidants. The effect of the organic solvents used in the polymerization bath was investigated. Prepared PEDOT/nylon 6 composite fabrics have superior electrical conductivity (0.75 S/cm, in ethanol solvent) compared to those of the other PEDOT composite fabrics. In particular, after five cycles of polymerization, the electrical conductivity of the composite fabric reached about 2 S/cm. However, the nylon 6 fabric was damaged by EDOT radical cations and the strong acidity of FepTS during the polymerization process. It was concluded that PTT fabric, which has excellent elastic recovery and acid resistance, is a suitable substrate for in situ polymerization of PEDOT, because the PEDOT/PTT composite fabric was hardly damaged during the polymerization process and its electrical conductivity is comparatively good (0.36 S/cm, in butanol solvent). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1326–1332, 2005     

Morphology and thermodynamic analysis of composite polymer particles prepared by soap‐free emulsion polymerization in the presence of poly(methyl methacrylate) and polystyrene as biseeds

Biseeds emulsion polymerization was investigated with poly(methyl methacrylate) (PMMA) and polystyrene (PSt) as biseeds and styrene (St) as second‐stage monomer, as well as with thermodynamic analysis; namely, the principle of minimum interfacial free‐energy change was utilized to explain the competitiveness of different seeds for second‐stage monomer and the final equilibrium morphology of composite polymer particles. The experimental results indicated the polymeric particles prepared had bimodal size distribution and the PMMA seed particles showed a higher chance of obtaining St than that of the PSt seed particles, which was in agreement with the computational outcome by the principle of minimum interfacial free‐energy change. Owing to the kinetic factors, the equilibrium morphology could not be reached in the experiments. However, the results demonstrated that double or multiple seeds emulsion polymerization could be used as a model experiment to study the morphology of polymer particle and the morphological prediction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2675–2680, 2004     

Preparation and characterization of hybrid organic–inorganic epoxide‐based films and coatings prepared by the sol–gel process

Hybrid organic–inorganic coatings and free‐standing films were prepared and characterized. The hybrids were prepared from [3‐(glycidyloxy)propyl]trimethoxysilane, diethoxy[3‐(glycidyloxy)propyl]methylsilane, poly(oxypropylene)s of different molecular weights end‐capped with primary amino groups (Jeffamines D230, D400, and T403), and colloidal silica particles with hydrochloric acid as a catalyst for the sol–gel process and water/propan‐2‐ol mixtures as solvents. The structure evolution during the network formation was followed by NMR spectroscopy and small‐angle X‐ray scattering; the surface morphology was tested by atomic force microscopy. The influence of the reaction conditions (the organosilicon precursor, oligomeric amine, ratio of functional groups, and method of preparation) on the network buildup and product properties was studied and examined. The mechanical testing, based on stress–strain experiments, in combination with dynamic mechanical thermal analysis served as an effective instrument for the optimization of the reaction conditions for the preparation of products with desired properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 937–950, 2004     

Performance enhancement of dye-sensitized solar cells using nanostructural TiO2 films prepared by a graft polymerization and sol–gel process

Nanostructural TiO₂ films with large surface areas were prepared by the combined process of graft polymerization and sol–gel for use in dye-sensitized solar cells (DSSCs). The surface of the TiO₂ nanoparticles was first graft polymerized with photodegradable poly(methyl methacrylate) (PMMA) via atom transfer radical polymerization (ATRP), after which the particles were deposited onto a conducting glass. The PMMA chains were removed from the TiO₂ films by UV irradiation to generate secondary pores, into which titanium isopropoxide (TTIP) was infiltrated. The TTIP was then converted into small TiO₂ particles by calcination at 450 °C, as characterized by energy-filtering transmission electron microscopy (EF-TEM) and field emission scanning electron microscopy (FE-SEM). The nanostructural TiO₂ films were used as a photoelectrode in solid-state DSSCs; the energy conversion efficiency was 5.1% at 100 mW/cm², which was higher than the values achieved by the pristine TiO₂ (3.8%) and nongrafted TiO₂/TTIP photoelectrodes (3.3%). This performance enhancement is primarily due to the increased surface area and pore volume of TiO₂ films, as revealed by the N₂ adsorption–desorption isotherm.     

Correlation between yttria stabilized zirconia particle size and morphological properties of NiO–YSZ films prepared by spray coating process

A systematic approach was taken to investigate the morphology of NiO–yttria stabilized zirconia (YSZ) films deposited by a spray coating process. The final morphological aspects of anode films were influenced by the particle size of YSZ powders and the milling time of the slurries used for film deposition. YSZ powders with average particle size of 17 and 52 nm were obtained from powders calcined at 800 and 1000 °C, respectively. The results obtained by rheological studies pointed out that slurries prepared from YSZ powders calcinated at 1000 °C and milling time of 20 h had more stability. All slurries presented thixotropic and pseudoplastic behaviors.     

Surface free‐energy analysis of poly(N‐vinyl‐2‐pyrrolidone–crotonic acid) copolymers prepared by γ‐ray‐induced polymerization technique

Composite hydrogels of pectin and polyacrylamide were synthesized and evaluated by scanning electron microscopy, atomic force microscopy, light microscopy, and dynamic mechanical analysis. The crosslinking polymerization of acrylamide in pectin solution resulted in a composite having a macroporous pectin domain with an interstitial polyacrylamide domain. This composite had improved mechanical properties compared to those of either polymer alone, and it absorbed and retained more water than crosslinked polyacrylamide alone. Furthermore, crosslinking polymerization of acrylamide in an existing pectinate scaffold resulted in a double‐network architecture, where filamentous polyacrylamide networks penetrated through pores of the pectin scaffold. It was found that pectins dictated the features of microstructure in the composites through regulating the coordination of phase separation of the two components and water partition between the two phases. Results from this study highlight potential new uses of pectins in protecting the physical structure of environmentally sensitive polymers from mechanical damage related to freezing, lyophilization, and other conditions experienced during their use in biomedical and industrial products. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1893–1901, 2004     

Thermal and chemical stability of Cu–Zn–Cr-LDHs prepared by accelerated carbonation

Layered double hydroxides Cu_xZn_6 − xCr₂(OH)₁₆(CO₃)·4H₂O with different molar ratios of Cu/Zn/Cr were synthesized by accelerated carbonation. The products were characterized by XRD, SEM, FT-IR and TG-DTG-DSC-MS. The chemical stability was tested by the modified Toxicity Characteristic Leaching Procedure (TCLP). The results showed that the products were the mixture of Cu_xZn_6 − xCr₂(OH)₁₆(CO₃)·4H₂O and (CuZn)₂(CO₃)(OH)₂, with similar thermal behavior. All products were chemically stable with reduced leaching at pH > 6 (Cu²⁺, Zn²⁺) or > 5 (Cr³⁺).     

Thermoresponsive poly(ϵ‐caprolactone)‐graft‐poly(N‐isopropylacrylamide) graft copolymers prepared by a combination of ring‐opening polymerization and sequential azide–alkyne click chemistry

A straightforward strategy is described to synthesize poly(?‐caprolactone)‐graft‐poly(N‐isopropylacrylamide) (PCL‐g‐PNIPAAm) amphiphilic graft copolymers consisting of potentially biodegradable polyester backbones and thermoresponsive grafting chains. PCL with pendent chlorides was prepared by ring‐opening polymerization, followed by conversion of the pendent chlorides to azides. Alkyne‐terminated PNIPAAm was synthesized by atom transfer radial polymerization. Then, the alkyne end‐functionalized PNIPAAm was grafted onto the PCL backbone by a copper‐catalyzed azide–alkyne cycloaddition. PCL‐g‐PNIPAAm graft copolymers self‐assembled into spherical micelles comprised of PCL cores and PNIPAAm coronas. The critical micelle concentrations of the graft copolymers were in the range 7.8–18.2 mg L^?1, depending on copolymer composition. Mean hydrodynamic diameters of micelles were in the range 65–135 nm, which increased as the length of grafting chains grew. PCL‐g‐PNIPAAm micelles were thermosensitive and aggregated upon heating. © 2014 Society of Chemical Industry     

Functionalization of carbon nanomaterials for advanced polymer nanocomposites: A comparison study between CNT and graphene

The allotropes of carbon nanomaterials (carbon nanotubes, graphene) are the most unique and promising substances of the last decade. Due to their nanoscale diameter and high aspect ratio, a small amount of these nanomaterials can produce a dramatic improvement in the properties of their composite materials. Although carbon nanotubes (CNTs) and graphene exhibit numerous extraordinary properties, their reported commercialization is still limited due to their bundle and layer forming behavior. Functionalization of CNTs and graphene is essential for achieving their outstanding mechanical, electrical and biological functions and enhancing their dispersion in polymer matrices. A considerable portion of the recent publications on CNTs and graphene have focused on enhancing their dispersion and solubilization using covalent and non-covalent functionalization methods. This review article collectively introduces a variety of reactions (e.g. click chemistry, radical polymerization, electrochemical polymerization, dendritic polymers, block copolymers, etc.) for functionalization of CNTs and graphene and fabrication of their polymer nanocomposites. A critical comparison between CNTs and graphene has focused on the significance of different functionalization approaches on their composite properties. In particular, the mechanical, electrical, and thermal behaviors of functionalized nanomaterials as well as their importance in the preparation of advanced hybrid materials for structures, solar cells, fuel cells, supercapacitors, drug delivery, etc. have been discussed thoroughly.