Synergistic antimicrobial effects of polyaniline combined with silver nanoparticles

Silver/polyaniline nanocomposites (Ag NPs/PANI) containing PANI nanofiber and Ag nanoparticles were synthesized by one-step approach without using any extra reducing agent or surfactant and applied to new antimicrobial agents. Morphologies and crystallinity of the nanocomposites were characterized with SEM and XRD. The results showed that the average diameter of the PANI nanofibers is around 50–150 nm, and the average particle size of Ag NPs is around 100 nm. The crystallinity of PANI gets better with increasing silver nitride concentration. UV–vis absorption spectroscopy analysis indicated that the Ag NPs have some effect on the microstructure of PANI. The antimicrobial properties of Ag NPs/PANI against Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus and fungous Yeast were evaluated using viable cell counts. The test results demonstrated that Ag NPs/PANI have enhanced antimicrobial efficacy compared to that of pure Ag NPs or pure PANI under the same test condition. The mechanism of the synergistic antimicrobial effect of Ag NPs with PANI was also proposed. In addition, thermal gravity analysis indicated that pure PANI and Ag NPs/PANI exhibit better thermal stability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

In situ fabrication of polyaniline‐silver nanocomposites using soft template of sodium alginate

Polyaniline (PANI)‐Ag nanocomposites were synthesized by in situ chemical polymerization approach using ammonium persulfate and silver nitrate as oxidant. Characterizations of nanocomposites were done by ultraviolet–visible ( UV–vis), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM). UV–vis, XRD and FTIR analysis established the formation of PANI/Ag nanocomposites and face‐centered‐cubic phase of silver. PANInanofibers were of average diameter ～ 30 nm and several micrometers in length. Morphological analysis showed that the spherical‐shaped silver nanoparticles decorate the surface of PANI nanofibers. Silver nanoparticles of average diameter ～ 5–10 nm were observed on the TEM images for the PANI‐Ag nanocomposites. Such type of PANI‐Ag nanocomposites can be used as bistable switches as well as memory devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Polyaniline with high crystallinity degree: Synthesis,structure, and electrochemical properties

Polyaniline (PANI) with high crystallinity degree was facilely synthesized on the surface of stainless steel net by galvanostatic method. The effect of polymerization current density on the characteristics of morphology and structure had been investigated by field emission scanning electron microscopy (FE‐SEM), Fourier transforms infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), and X‐ray diffraction (XRD). FE‐SEM observations disclosed that PANI was deposited as nanofibers and their diameters decreased with the polymerization current density. FTIR studies revealed that degree of oxidation increased in order PANI‐2 < PANI‐6 < PANI‐10. XPS measurements displayed that PANI polymerized at 6 mA cm^?2 (PANI‐6) exhibited much higher doping level of 77.8%, which favored the conductivity. XRD analysis discovered that the obtained PANI showed high crystallinity degree in which PANI‐6 possessed highest crystallinity degree (X_cr) up to 67%. Electrochemical performances of PANI as electrode materials were studied via cyclic voltammetry. The results presented that PANI‐6 possessed greater discharge capacity and better reversibility. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40827.     

Room temperature preparation,electrical conductivity,and thermal behavior evaluation on silver nanoparticle embedded polyaniline tungstophosphate nanocomposite

An advanced nanocomposite, polyaniline tungstophosphate (PANI‐WP) cation exchanger, was synthesized by simple solution method and treated with silver nitrate resulting silver embedded PANI‐WP (PANI‐WP/Ag). Spectroscopic characterization of PANI‐WP/Ag was carried out by scanning electron microscopy, fourier transform infrared spectroscopy, UV‐Visible spectroscopy, and X‐ray diffraction. Electrical conductivity measurements and thermal effect on conductivity of PANI‐WP/Ag was studied after acid treatment. The dc electrical conductivity was found 3.06 × 10⁻³ S cm⁻¹ for HCl doped, measured by 4‐in line‐probe dc electrical conductivity measuring technique. Thermal conductivity is stable with all temperatures in isothermal studies showing excellent stability of PANI‐WP/Ag material. Hybrid showed better linear Arrhenius electric conducting response for semiconductors, stable upto 120°C. It was observed that conductivity is at the border of metallic and semiconductor region. POLYM. COMPOS., 37:2460–2466, 2016. © 2015 Society of Plastics Engineers     

Synthesis of PANI‐CaO composite nanofibers with controllable diameter and electrical conductivity

We report the direct evidence of the control of diameter, surface morphology, and conductivity of polyaniline (PANI) nanofibers by systematically varying the addition of CaO in the range from 0.005 to 1.00 g. The possible incorporation of CaO in PANI was revealed by Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy. The diameter of PANI nanofibers was varied with the variation of CaO loadings. The low diameter, 30 nm was obtained for the highest loading of CaO (1.00 g). Field emission scanning electron microscopy analysis showed that the addition of CaO between the range of 0.005 and 1.00 g, always produces nanofibers with regular and uniform surface morphology and without secondary growth and agglomeration of primary nanoparticles. Conductivity measurements showed that the highest conductivity value of 6.329 S cm⁻¹ could be obtained by the addition of the lowest amount of CaO (0.005 g). Furthermore, we observed the decreasing trend of conductivity with the increasing of CaO loadings. POLYM. COMPOS., 36:359–366, 2015. © 2014 Society of Plastics Engineers     

Interfacial polymerization of morphologically modified polyaniline: from hollow microspheres to nanowires

BACKGROUND: Polyaniline (PANI) has attracted much attention in many fields due to its chemical and physical properties, and different nanostructures of PANI changing from one‐dimensional to three‐dimensional have been obtained. By changing the concentration of cetyltrimethylammonium bromide (CTAB), the morphology of hydrochloric acid‐doped polyaniline could be changed from one‐dimensional nanoneedles or nanowires with a network structure (50–100 nm in diameter) to three‐dimensional hollow microspheres (ca 400 nm in outer diameter) via combining interfacial polymerization and self‐assembly process. RESULTS These different nanostructures of PANI were proved using scanning electron and transmission electron microscopies. A plausible mechanism of the formation of the changeable nanostructures of PANI may be different from that of interfacial polymerization without surfactant or a traditional homogenous reaction system using CTAB as surfactant. CONCLUSION The results obtained from Fourier transform infrared spectrometry, X‐ray diffraction and the four‐probe method showed that the molecular structure of PANI does not change with increasing CTAB concentration, but crystallinity and conductivity of PANI increase with surfactant concentration. Copyright © 2007 Society of Chemical Industry     

Characterization and electron transport properties of polyaniline nanocomposites containing silver chloride nanoparticles embedded on the gelatin surface

ABSTRACT

Polyaniline (PANI) encapsulating silver chloride nanoparticles embedded on the surface of gelatin nanofibers were prepared. The interaction of PANI/gelatin with AgCl and crystallinity of the composites are characterized by FTIR and XRD. The surface framework of the composites was studied by SEM and TEM. Increase of AgCl has brought out significant increase of DC conductivity of the composites. The hydrophilic GEL acts as a plasticizer in the PANI/GeL-AgCl increases the mobility of charge carriers in the composites which influences the conductivity. Such composites are used in electric devices, sensors, and functional coatings for their high electrical conductivity.     

Polyaniline–nylon 6 composite nanowires prepared by emulsion polymerization and electrospinning process

Polyaniline (PANI) nanoparticles doped with the dodecylbenzene sulfonic acid (DBSA) were prepared and these nanoparticles were electrospun with nylon 6 as matrix material into fiber web. Depending on the contents and concentrations of PANI and nylon 6, either nylon 6 nanofibers (～96 nm) or PANI‐nylon 6 composite nanofibers (～12 nm) were obtained. The electrical conductivity of PANI(DBSA)–nylon 6 electrospun fiber web was lower than that of PANI(DBSA)‐nylon 6 film because of the low crystallinity of the PANI(DBSA)–nylon 6 composite electrospun fiber web. However, it showed that the PANI–nylon 6 composite nanofibers would have applications as the nanowires for connecting the microelectromechanical system (MEMS). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1277–1286, 2006     

Polyaniline/silver nanocomposites synthesized via UV–Vis‐assisted aniline polymerization with a reversed micellar microemulsion system

Polyaniline (PANI)/silver (Ag) nanocomposites were successfully synthesized within a sodium dodecyl sulfate reverse micro‐emulsion system and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, ultraviolet spectrometry, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and electrochemical methods. The results show that the core‐shell nanoparticles of less than 100 nm may be synthesized with PANI as shell formed around a core of nanoparticle. PANI/Ag nanocomposite prepared by this method has better thermal stability, higher conductivity, and electrochemical performance. The maximum conductivity (95.5 S/cm) was obtained when W₀ (water‐oil ratio) is 22. Cyclic voltammograms results show that PANI/Ag prepared by this method has a high response current and large capacitance. Polarization results show that E_corr (174.1 mV) and I_corr (50.6 μA/cm²) are better than the results for PANI and for PANI/Ag prepared by micro‐emulsion method. PANI/Ag nanocomposites prepared by the current method have potential applications in electrode materials, capacitors, conductive adhesives, and anticorrosion materials. POLYM. COMPOS. 37:1064–1071, 2016. © 2014 Society of Plastics Engineers     

Nanocomposites of silver nanoparticle and dinonylnaphthalene disulfonic acid‐doped thermoreversible polyaniline gel

Silver/polyaniline‐dinonylnaphthalene disulfonic acid (PANI‐DNNDSA) gel nanocomposites are prepared from the reduction of silver salt by polyaniline in formic acid medium. Scanning electron micrographs (SEM) indicate the presence of three‐dimensional fibrillar network structure and the silver nanoparticles remain dispersed within the PANI‐DNNDSA fibrillar network. Differential scanning calorimetric (DSC) study shows reversible first‐order phase transition characterizing the composite to behave as a thermoreversible gel. Transmission electron micrographs (TEM) show a decrease of nanoparticle size with increasing AgNO₃ concentration. Wide angle X‐ray scattering (WAXS) patterns show lamellar structure in the gel as well as in the gel metal nanocomposites (GMNCs) and the two melting peaks in the DSC patterns correspond to the melting of monolayer and bilayer crystals produced from the interdigitation of DNNDSA tails anchored from PANI chains within the PANI lamella. The above melting points are greater in the GMNCs than that of pure gel indicating the formation of complex melting thermogram with crystallites produced from the anchored surfactants tails at the surface of Ag nanoparticles. The GMNCs show a higher thermal stability than that of pure PANI‐DNNDSA gel. PANI‐DNNDSA gel has an emission peak at 354 nm but fluorescence quenching occurs in the GMNCs and the emission peak becomes red shifted. Also in the UV–vis spectra the π band‐polaron band transition peak shows a red shift and the DC conductivity increases with increasing Ag nanoparticle concentration in the GMNCs. The current (I)–voltage (V) characteristic curves indicate Ohmic nature of conductivity of the gel and the current at the same voltage increases appreciably with increasing Ag nanoparticle concentration. These GMNCs are easily processible due to its thermoreversible nature. So, an easily processible, thermally stable and highly conducting DNNDSA‐doped PANI‐Ag gel nanocomposite with interesting photoluminescent property has been successfully developed suitable for optoelectronic applications. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Preparation and characterization of polyaniline nanofiber colloids

Polyaniline (PANI) nanofibers were prepared via the reaction of aniline with ammonium persulfate carried out in ethylene glycol (EG) medium without water. These purified PANI nanofibers could be dispersed in water and other polar solvents, such as ethanol, EG, and N,N‐dimethylformamide, to form colloids. The morphology and structure of the PANI nanofibers were characterized and the effects of mechanical stirring on the morphology, structure, and electrical performance of PANI were investigated. The results indicated that the intermolecular H‐bonding interaction between molecules of PANI and alcohol is advantageous to the one‐dimensional growth of PANI, and a stirring reaction results in a lager size, a higher doping level, conductivity, degree of crystallinity, and oxidation than a nonstirring reaction. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.     

Poloxamer and gelatin gel guided polyaniline nanofibers: synthesis and characterization

A rapid polymerization technique was successfully employed to synthesize interconnected polyaniline (PANI) nanofibers using chemical oxidative polymerization inside a soft template. The thermoreversible hydrogels of Lutrol F 127 and gelatin were used as templates where the interstices present in the hydrogel were responsible for the formation of PANI nanofibers with a diameter in the range ca 70?75 nm and ca 50?55 nm respectively and several micrometers in length. The doped emeraldine salt of PANI was confirmed by Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy. The crystallinity of as‐synthesized PANI nanofibers for both cases was verified by an X‐ray diffraction study while thermogravimetric analysis was performed to compare the relative stability of the synthesized PANI nanofibers. The electrical conductivities of polymerized PANI are of the order of 10^?3 S cm^?1 and are compared with those of template fabricated PANI. The Lutrol F 127 gel guided PANI nanofibers showed a rectifying property while the gelatin gel guided PANI provided a simple ohmic nature. © 2013 Society of Chemical Industry     

Synthesis of high conductivity Polyaniline/Ag/graphite nanosheet composites via ultrasonic technique

A new process for the synthesis of high conductivity polyaniline/Ag/graphite nanosheet (PANI/Ag/NanoG) composites was developed. Graphite nanosheet was prepared by treating the expanded graphite in aqueous alcohol solution using sonication, and a uniform silver film about 470 nm thick was obtained on graphite nanosheet surface via an improved electroless plating method. Then PANI/Ag/NanoG composites were fabricated via in situ polymerization of aniline monomer in the presence of silver coated graphite nanosheet through using ultrasonic technique. The sliver particles and composites were evidenced by scanning and transmission electron microscopy examinations, the results showed that the silver coated graphite nanosheet particles played an important role in forming conducting bridge in polyaniline matrix. According to the electrically test, the conductivity of the PANI/Ag/NanoG composites was dramatically increased compared with pure PANI. From the thermogravimetric analysis, the PANI/Ag/NanoG composites exhibited a beneficial effect on the thermal stability of pure PANI.     

Studies on the synthesis of electrospun PAN‐Ag composite nanofibers for antibacterial application

We have successfully synthesized polyacrylonitrile (PAN) nanofibers impregnated with Ag nanoparticles by electrospinning method at room temperature. Briefly, the PAN‐Ag composite nanofibers were prepared by electrospinning PAN (10% w/v) in dimethyl formamide (DMF) solvent containing silver nitrate (AgNO₃) in the amounts of 8% by weight of PAN. The silver ions were reduced into silver particles in three different methods i.e., by refluxing the solution before electrospinning, treating with sodium borohydride (NaBH₄), as reducing agent, and heating the prepared composite nanofibers at 160°C. The prepared PAN nanofibers functionalized with Ag nanoparticles were characterized by field emission scanning electron microscopy (FESEM), SEM elemental detection X‐ray analysis (SEM‐EDAX), transmission electron microscopy (TEM), and ultraviolet‐visible spectroscopy (UV‐VIS) analytical techniques. UV‐VIS spectra analysis showed distinct absorption band at 410 nm, suggesting the formation of Ag nanoparticles. TEM micrographs confirmed homogeneous dispersion of Ag nanoparticles on the surface of PAN nanofibers, and particle diameter was found to be 5–15 nm. It was found that all the three electrospun PAN‐Ag composite nanofibers showed strong antibacterial activity toward both gram positive and gram negative bacteria. However, the antibacterial activity of PAN‐Ag composite nanofibers membrane prepared by refluxed method was most prominent against S. aureus bacteria. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Melt‐processed polyaniline nanofibers/LDPE/EAA conducting composites

The melt‐processable polyaniline nanofibers doped with superfluous dodecylbenzenesulfonic acid (PANI‐DBSA) were synthesized using the interfacial polymerization and thermal doping technique. Conducting composites composed of PANI‐DBSA nanofibers, low‐density polyethylene (LDPE), and ethylene‐acrylic acid copolymer (EAA) as compatibilizer were prepared by melt processing. The effects of PANI‐DBSA nanofibers on the electrical conductivity, and mechanical properties, and morphological structure of the composites were investigated. As a result, the conducting composites had lower percolation threshold (4 wt%) due to the easy formation of conducting paths for fibrillar‐like PANI‐DBSA in the LDPE matrix, which was also confirmed by the frequency dependence of the real part of the AC conductivity. The Scanning electron microscopy (SEM) images indicated that the PANI‐DBSA nanofibers were dispersed uniformly in the matrix. The mechanical properties of the composites were improved at the low PANI‐DBSA load (about 1 wt%), but they were deteriorated at high PANI‐DBSA content. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Effect of β‐cyclodextrin on the solid‐state synthesized polyaniline doped with hydrochloric acid

Polyaniline (PANI) salts doped with hydrochloric acid were prepared by using solid‐state polymerization in the presence of β‐cyclodextrin (β‐CD) at room temperature. The fourier transform infrared (FTIR) spectra, ultraviolet‐visible absorption spectra, X‐ray diffraction patterns were used to characterize the molecular structures of these polymers. Cyclic voltammetry study and conductivity measurements were done to investigate their electrochemical behaviors. The morphology of polymers was studied by the scanning electron microscopy and transmission electron microscopy. The results showed that PANI salts prepared in the presence of β‐CD had different physicochemical characteristics compared with PANI salt prepared in the absence of β‐CD. When the molar ratio of aniline to β‐CD was 80/20, the obtained PANI salt displayed higher crystallinity, conductivity and electrochemical properties. However, these properties were opposite on condition that the molar ratio of aniline to β‐CD was 50/50. The results also revealed that the morphology of PANI salt was affected by β‐CD, especially at aniline/β‐CD molar ratio in the feed of 50/50, in which PANI salt displayed rodlike structure morphology with a diameter of near 80–100 nm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of nanosize polyaniline by solid‐state polymerization and determination of crystal structure

BACKGROUND: Nanosize polyaniline has several advantages in both the fabrication of nanodevices and for preparing nanoscale electrical connections in highly conducting polymer composites. RESULTS: Nanosize polyaniline with a diameter of 30–60 nm was prepared using a solid‐state polymerization process (PANI‐S) by mixing an equimolar quantity of ammonium persulfate and anilinium chloride crystals with a mortar and pestle. Polyaniline was also synthesized using a conventional oxidative polymerization method (PANI‐C) in an aqueous medium for comparison. Conductivity and contact angle measurements, infrared spectroscopy, ultraviolet spectroscopy, transmission electron microscopy and thermogravimetric analysis were carried out. An in‐depth investigation of the crystal structure of these polymers was carried out through powder X‐ray diffraction analysis. CONCLUSION: PANI‐S exhibited lower conductivity due to the presence of less emeraldine base form, lower crystallinity, greater d‐spacing and greater inter‐chain separation than PANI‐C. The hydrophilicity and thermal stability of PANI‐S were higher than those of PANI‐C. The unit cell volume of PANI‐S was much higher, resulting in a larger crystallite size and a greater number of atoms in the unit cell than PANI‐C. Copyright © 2009 Society of Chemical Industry     

Electromagnetic interference shielding with polyaniline nanofibers composite coatings

Hydrochloric acid doped polyaniline (PANI) nanofibers were synthesized by an interfacial polymerization with tetrachloride as the organic solvent and with a relatively higher aniline concentration. The doped PANI nanofibers were dispersed in cyclohexanone and the dispersion was mixed with solution of polyacrylate to prepare PANI nanofibers composite coatings. It was found that the yield of the doped PANI nanofibers can be as high as 23%, though a small amount of irregular shaped PANI particles and PANI nanofibers with relatively larger diameter were also obtained. The conductivity of the PANI nanofibers based composite coatings increased with the PANI nanofibers contents and a percolation threshold of 0.2 was demonstrated. The shielding effectiveness of the PANI nanofibers based coatings increased with PANI nanofibers loadings and shielding effectiveness as high as 63 dB can be achieved with PANI nanofibers loadings of 45%. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers     

Conducting polyaniline nanofiber networks prepared by the doping induction of camphor sulfonic acid

Branched nanofibers of conducting polyaniline (PANI) buried in the crystals of camphor sulfonic acid (CSA) were prepared from an m‐cresol solution of PANI and excessive CSA. After the excessive CSA was dissolved through ultrasonication in deionized water, networks of PANI nanofibers with spherical nodes, nanoparticles, leaf‐vein‐shaped nanofibers, and so forth were obtained according to the strength of the ultrasonic treatment. The X‐ray diffraction patterns of the CSA‐doped PANI showed high crystallinity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1537–1540, 2003     

Synthesis of higher soluble nanostructured polyaniline by vapor‐phase polymerization and determination of its crystal structure

Higher soluble nanostructured polyaniline was prepared by vapor‐phase polymerization after passing aniline vapor through an aqueous acidic solution of ammonium persulfate (PANI‐V). Polyaniline was also synthesized by the conventional oxidative polymerization method (PANI‐C) in an aqueous medium for the comparison of its properties with PANI‐V. PANI‐V exhibited lower conductivity but higher hydrophilicity and higher solubility (2–3 times) in different solvents, such as tetrahydrofuran, N‐methyl‐2‐pyrrolidone, dimethylsulfoxide, N,N‐dimethyl formamide, and m‐cresol at room temperature compared with that of PANI‐C. The thermal stability of PANI‐V was higher than that of PANI‐C. In‐depth investigations of the crystal structures of PANI‐C and PANI‐V were performed through powder X‐ray diffraction analysis. The PANI‐V showed a less ordered structure with a lower crystallinity and crystallite size and with a higher d‐spacing and interchain separation compared with PANI‐C. The unit cell volume of PANI‐V was significantly higher with a greater number of atoms in the unit cell than that of PANI‐C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009