Fabrication and characterization of chitosan/poly(vinyl alcohol) electrospun nanofibrous membranes containing silver nanoparticles for antibacterial water filtration

Electrospun nanofibrous membranes (ENMs) were fabricated based on chitosan/poly(vinyl alcohol) (CS/PVA) with a 70/30 mass ratio containing silver nanoparticles (AgNPs) via the electrospinning method. AgNPs were produced on the surface of CS/PVA nanofibers by adding AgNO₃ to a CS/PVA blend solution as a silver rendering component. The presence of AgNPs in the polymer blend solution was detected by UV spectrophotometry. The morphology of nanofibers before and after cross-linking with glutaraldehyde was investigated by the field emission scanning electron microscopy. The formation and size distribution of AgNPs onto the surface of nanofibers were observed by transmission electron microscopy and confirmed by energy dispersing X-ray spectroscopy. As-spun and cross-linked CS/PVA nanofibers revealed a smooth surface with diameters ranging from 58 to 73 nm and 95 to 109 nm, respectively. The effect of AgNP formation on the chemical structure of nanofibers was explored by Fourier transform infrared spectroscopy. Static and dynamic antibacterial filtration efficiencies of CS/PVA ENMs, containing differing amounts of AgNO₃, have been tested against Escherichia coli, a gram negative bacterium. The antibacterial assessment results exhibited a significant increase in both static and dynamic antibacterial filtration efficiencies of the prepared CS/PVA ENMs by addition of AgNO₃ as a bactericidal agent.     

Performance assessment of poly (methacrylic acid)/silver nanoparticles composite as corrosion inhibitor for aluminium in acidic environment

This article reports the preparation of poly (methacrylic acid)/silver nanoparticles composite (PMAA/AgNPs) by in situ mixing of aqueous solutions of PMAA and 1 mM AgNO₃ with natural honey as reducing and stabilizing agent. The prepared PMAA/AgNPs composite was characterized by UV–vis spectroscopy, Fourier transformed infrared, X-ray diffraction and energy dispersive spectroscopy (EDS) while the morphology of the AgNPs in the composite was obtained by transmission electron microscopy (TEM). TEM results revealed that the AgNPs were spherical in shape. The performance of PMAA/AgNPs composite as anticorrosion material for Al in acidic environment was examined by electrochemical, weight loss methods, complemented by surface analysis characterization with scanning electron microscopy (SEM), EDS and water contact angle measurements. Results obtained indicate that PMAA/AgNPs composite is effective corrosion inhibitor for Al in an acid-induced corrosive environment. Inhibition efficiency increased with increase in composite concentration but decreased with rise in temperature. From potentiodynamic polarization results, PMAA/AgNPs composite is found to function as a mixed-type corrosion inhibitor. The adsorption of the composite onto Al surface was found to follow El-Awady et al. adsorption isotherm model. SEM, EDS and water contact angle results confirmed the adsorption of the composite on Al surface.     

Maleic anhydride based copolymer dispersions for surface modification of polar substrates

In this article, we report the modification of poly(styrene-alt-maleic anhydride) (PSMA) with monofunctional amine-terminated poly(dimethyl siloxane) (PDMS–NH₂) by thermal imidization, followed by the preparation and characterization of a surfactant-free artificial latex thereof and application of this latex onto cotton fabric. The imidization reaction was monitored by NMR and attenuated total reflection Fourier transform infrared (ATR–FTIR) spectroscopy. 1,2-Cyclohexyldicarboxylic anhydride was chosen as a model compound for the PSMA copolymer; this allowed a more detailed characterization by NMR and ATR–FTIR spectroscopy. After the PSMA/PDMS–NH₂ imidization reached completion, a fraction of the anhydrides were ammonolyzed. In this way, a self-emulsifying latex with an average particle diameter of approximately 145 nm and a ζ potential of −56 mV was obtained. It was found that the PDMS-modified PSMA latex in which 30 mol% of the initial amount of anhydride groups were previously imidized by using PDMS-NH₂ and a fraction of the anhydrides were ammonolyzed with 0.3 eq. of NH₃ (PSMA30) was stable in the pH range 4–10. The water contact angle values of the latex-coated cotton textile fabric indicated a hydrophobized surface, with a static contact angle of 135.7°± 1.2°. The washing studies with a standard soap solution of the cotton samples with or without crosslinker showed that the crosslinked PSMA30 offered a good coating durability to the cotton. This waterborne resin based on surfactant-free latices displayed promising properties for coating applications and seemed to be very suitable for the hydrophobization of polar surfaces. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Peroxide‐catalyzed swell grafting of maleic anhydride onto polypropylene

A new grafting method was developed to incorporate maleic anhydride directly onto solid‐state polypropylene powders. Maleic anhydride grafts altered the nonpolar characteristics of polypropylene so that much better mixing was achieved in blends and composites of polypropylene with many other polymers and fillers. Maleic anhydride was grafted onto polypropylene by the peroxide‐catalyzed swell grafting method, with a maximum extent of grafting of 4.60%. Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, tensile testing, and impact testing were used to characterize the isotactic polypropylene (iPP), maleic anhydride grafted polypropylene (MAH‐g‐iPP), and (isotactic polypropylene)/(calcium carbonate) composites (iPP/CaCO₃). The crystallinity and heat of fusion of the MAH‐g‐iPP decreased as the extent of grafting increased. The mechanical properties of the CaCO₃ filled polypropylene were improved by adding MAH‐g‐iPP as a compatibilizing agent. The dispersion of the fillers in the polymer matrix and the adhesion between the CaCO₃ particles and the polymer matrix were improved by adding the compatibilizer.     

Development of a nanocomposite of polypropylene with biocide action from silver nanoparticles

This article presents the production of films based on blends of polypropylene (PP) and modified PP with the insertion of silver nanoparticles (AgNPs) produced to generate a bactericidal effect. The 50/50 blend of PP and PP modified by irradiation in acetylene at a dose of 12.5 kGy was processed in a twin‐screw extruder. The addition of AgNPs in poly(N‐vinyl‐2‐pyrrolidone) (PVP) solution was performed during processing in the extruder. The material was characterized by ultraviolet–visible spectroscopy, scanning electron microscopy, energy‐dispersive spectroscopy, transmission electron microscopy, cytotoxicity assay, and a reduction in colony‐forming units. The PP–PVP1% AgNP film showed silver particles in the nanoscale, presented no cytotoxicity for mammalian cells, and presented antimicrobial effects against Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus bacteria. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42218.     

Nanocomposites based on high impact polystyrene/silver nanoparticles: Effect of silver nanoparticles concentration on the reaction evolution,morphology, and impact strength

Nanocomposites based on high impact polystyrene (HIPS) and silver nanoparticles (AgNPs) were synthesized via in situ bulk‐suspension polymerization adding a colloidal suspension of AgNPs in styrene from the beginning of the reaction. The concentrations of AgNPs in the final nanocomposites were 0, 0.025, 0.10, and 1.0 wt%. The rate of polymerization and free radicals concentration were found to decrease with increasing AgNPs concentration. For nanocomposites with 0.025 and 0.10 wt% of AgNPs, the phenomenon of phase inversion (PI) during the mass polymerization occurred within the same range as that for the blank HIPS. Further, the impact strength of these nanocomposites did not present any changes as compared to the blank HIPS. However, there was no sign of the PI phenomenon in the case of 1.0 wt% of AgNPs, due to a decrease in the amount of free and graft polystyrene onto the rubber chain as the free radicals concentration diminishes with an increase in AgNPs. In this case the impact strength doubles the values of the blank HIPS due to the presence of a interpenetrated polymer network of crosslinked grafted rubber and polystyrene (PS) instead of the formation of a defined morphology. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Functionalized polymeric silver nanoparticle hybrid network as a dual antimicrobe: Synthesis,characterization, and antibacterial application

The present work describes a novel method for the synthesis of silver polymer nanocomposite for the delivery of amoxicillin (AMO). Silver nanoparticles (AgNPs) were synthesized with chitosan and silver nitrate. The reaction parameters were optimized. Three‐dimensional polymeric networks were synthesized by simple free‐radical graft copolymerization. UV–visible spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, SEM, atomic force microscopy, dynamic light scattering, and zeta potential analysis were used for the complete characterization of the samples. Swelling studies and swelling factors were evaluated. In vitro release of AMO and AgNPs at physiological pHs was analyzed using the Peppas kinetic model to explain the drug delivery mechanism. Cytotoxicity, free‐radical scavenging, and antibacterial activities were analyzed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43479.     

Facile modification of thin-film composite nanofiltration membrane with silver nanoparticles for anti-biofouling

This study focuses on the modification of a commercial nanofiltration (NF) membrane by an in-situ reaction to load silver nanoparticles (AgNPs) for anti-biofouling. Poly (vinyl alcohol) (PVA) was coated onto the NF membrane firstly, and silver salt was then deposited on the surface of PVA layer. Through thermal reduction, AgNPs with 10–20 nm in diameter were formed and immobilized onto the membrane surface by the interaction between AgNPs and PVA, as confirmed by UV–vis absorption spectrum, SEM and XPS analysis. Compared to the pristine NF90 membrane, the PVA composite membranes (NF90-PVA) and AgNPs (NF90-PVA-AgNPs) modified membranes exhibit lower water flux and slightly higher salt rejection. Release of silver ion experiments were assessed via batch method, and the results indicate silver ion can be released from the AgNPs modified membrane continuously and steadily, which may be responsible for the improved and long-time antibacterial ability of the membrane. Due to the simplicity of the method, the ability to immobilize the AgNPs to avoid leaching out, and the strong antibacterial activity, this NF90-PVA-AgNPs composite membrane displays potential applications in industrial water-treatment.     

Plasma‐enhanced deposition of silver nanoparticles onto polymer and metal surfaces for the generation of antimicrobial characteristics

Silver nanoparticle thin layers were deposited onto formaldehyde‐radio frequency (RF)‐plasma‐functionalized medical‐ and food‐grade silicone rubber, stainless steel, and paper surfaces. The silver deposition was carried out under ex situ plasma conditions using the Tollen's reaction. Results from survey and high‐resolution electron spectroscopy for chemical analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X‐ray spectroscopy investigations confirmed the presence of thin silver layers on the plasma‐exposed and subsequently modified substrate surfaces. In addition, SEM and AFM demonstrated the nanoparticle‐based morphology of the deposited layers. Our results showed that thin macromolecular layers bearing aldehyde functionalities can be deposited onto silicone rubber, stainless steel, and paper surfaces. The bactericidal properties of the silver‐coated surfaces were demonstrated by exposing them to Listeria monocytogenes. No viable bacteria were detected after 12 to 18 h on silver‐coated silicone rubber surfaces. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1411–1422, 2004     

One-pot synthesis of gelatin-based,slow-release polymer microparticles containing silver nanoparticles and their application in anti-fouling paint

Gelatinous polymer matrix microparticles containing silver nanoparticles (AgNPs) were prepared by a novel method to obtain quasi non-swelling anti-fouling paint additives with slow-release characteristics. A w/o type dispersion were elaborated with the aqueous phase of gelatin, urea, silver-nitrate and formaldehyde dispersed in linseed oil. Gelatin was cross-linked by formaldehyde, together with urea for limiting the swelling of the product. Silver-nitrate was reduced with the assistance of gelatin and formaldehyde into homogenously dispersed AgNPs. The microparticles and embedded AgNPs were visualized by scanning and transmission electronmicroscopy. Encapsulated AgNPs with ∼18 nm crystallite size were identified by X-ray powder diffraction. Characterization of gelatin–urea–formaldehyde polymer matrices was carried out by attenuated total reflectance FTIR spectroscopy. Silver dissolution from microparticles and paints with AgNP-containing microparticles was measured by inductively coupled plasma spectrometer and resulted in highly sustained release, compared to unmodified gelatin microparticles and paints containing uncapsulated silver salts. A 7-month-long fouling experiment run in natural sweetwater media showed that solvent-based acrylic paint with AgNPs-containing gelatinous microparticles as additives offered resistance against biofouling at low Ag-release ratio.     

Structural and spectroscopic properties of some neodymium-boro-germanate glasses and glass ceramics embedded with silver nanoparticles

Neodymium-boro-germanate glasses and glass ceramics (with Nd₂O₃ contents up to 40 mol%) embedded with silver metallic nanoparticles (AgNPs) were prepared by the melt-quenching technique. Two series of samples (with AgNPs and without AgNPs) were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance ultraviolet–visible (DR-UV–vis) spectroscopy and photoluminescence (PL) spectroscopy. XRD data reveal that for both series the samples with x < 40 mol% Nd₂O₃ are basically amorphous containing only small amounts of a crystalline phase (identified as crystalline B₂O₃) while for samples x = 40 mol% Nd₂O₃ an important amount of a crystalline phase (identified as the NdBO₃ orthorhombic phase) is present. FT-IR spectroscopy data show that addition of controlled amounts of Nd₂O₃ and AgNPs changes the structural units that build up the host glass ceramic network. These changes were confirmed also by the photoluminescence spectra that show that addition of AgNPs to the host matrix produces changes at the level of emission peaks. The positive values of bonding parameter (δ) calculated based on DR-UV–vis data indicate a covalent character of the bonds from the studied samples.     

Tunable release of silver nanoparticles from temperature-responsive polymer blends

Polymer blends of thermoresponsive poly(N-isopropylacrylamide) and poly(methyl methacrylate) with in situ synthesized silver nanoparticles (AgNPs) are proposed as stimuli-responsive antimicrobial materials. AgNPs were prepared in the semi-dried polymer blends by N-methyl-2-pyrrolidone reduction. Temperature controlled kinetic of silver release was examined for different weight ratios of the polymers. Synthesized AgNPs were characterized by transmission electron microscopy and temperature-dependent releasing was analyzed by ultraviolet–visible and atomic absorption spectroscopies. Temperature-dependent changes of polymer matrices were observed by confocal microscopy and infrared spectroscopy. It was shown that the polymer weight ratio determines both, starting time and kinetic of nanoparticle release. Antibacterial activities of the prepared material were demonstrated on Gram-positive Staphylococcus aureus (S. aureus) and gram-negative Pseudomonas aeruginosa (P. aeruginosa). Quantitative evaluation of antimicrobial efficacy of prepared materials was performed on the base of inhibition zone size. It was shown that prepared materials could serve as effective antibacterial coating with quick antimicrobial response.     

Hydrophilic modification of a polyimide film surface

The surface of a polyimide [poly(biphenyl 3,3′,4,4′-dianhydride-p-phenylene diamine)] film was modified with an O₂ glow plasma and subsequent treatment with polyethyleneimine (PEI) and poly(maleic anhydride-co-vinyl methyl ether) (PMAVM). The density of peroxide groups formed on the surface after O₂ plasma exposure was determined with 1,1-diphenyl-2-picrylhydrazyl and was found to level off to 1.2 nmol/cm² within the plasma exposure time of 20-60 s. The peroxide groups formed were utilized to immobilize PEI covalently onto the plasma-treated polymer film. After that, PMAVM was immobilized on the surface through the formation of amide bonds between the amino groups of PEI and the anhydride groups of PMAVM. The water contact angle on the modified films showed that the hydrophilic durability of the PMAVM-PEI-modified polyimide film was superior to that of the polyimide film treated by O₂ plasma alone.     

Functional Copolymer/Organo-MMT Nanoarchitectures: XXVI. Fabrication and Characterization of Electrospun Nanofibers from PCL/ODA-MMT and Copolymer-g-PLA/ Ag-MMT Blends

We synthesized poly(?-caprolactone)/octadecyl amine-montmorillonite clay nanocomposite as a matrix polymer by solution intercalative method and new amphiphilic poly(maleic anhydrde-alt-1-octadecene)-g-poly(L-lactic acid)/Ag⁺-montmorillonite clay nanocomposite as a partner polymer by interlamellar graft copolymerization of lactic acid onto anhydride copolymer in the presence of silver salt of montmorillonite clay as catalyst-nanofiller. Novel polymer nanofibers were fabricated by electrospinning of matrix/partner blends with different volume ratios. The nanocomposites and nanofibers were investigated by Fourier transform infrared spectroscopy, thermal gravimetric analysis–differential scanning calorimetry, and scanning electron microscope–transmission electron microscope methods. The diameters, morphologies, and thermal behavior of fibers were strongly depended on the partner-polymer nanocomposites loadings. The fabricated biocompatible and biodegradable nanofibers can be utilized for biomedical and filtration applications.     

Preparation of modified sodium lignosulfonate hydrogel–silver nanocomposites

In this article, modified sodium lignosulfonate (MSLS) hydrogel particles were prepared using sodium lignosulfonate as starting material. The hydrogel particles exhibit a reversible property transformed between the two states of macrohydrogel and microhydrogel by ultrasonic dispersion and vacuum drying. Using this property, highly stable and uniformly dispersed silver nanoparticles (AgNPs) have been prepared via in situ reduction of silver ions (silver nitrate) in the microhydrogel aqueous dispersion with sodium borhydride. The hybrid microhydrogel with AgNPs was transformed into MSLS hydrogel–silver nanocomposites by drying under vacuum at 40°C. X‐ray diffraction, ultraviolet–visible (UV–vis) spectrophotometry, Fourier transform infrared spectra, atomic absorption spectroscopy, transmission electron microscopy, and scanning electron microscopy were used to characterize the composite system. The results show that the size of spherical silver nanoparticles incorporated in the hydrogel framework is about 10 nm. POLYM. COMPOS., 34:860–866, 2013. © 2013 Society of Plastics Engineers     

Preparation of AgNPs/PS composite via reverse microemulsion polymerization

Silver nanoparticles (AgNPs) were synthesized in reverse microemulsions using silver nitrate as silver source, hydrazine hydrate as reducing agent, n‐heptane as oil phase, cetyl trimethyl ammonium bromide (CTAB) as surfactant, and isoamyl alcohol as cosurfactant. A uniform silver nanoparticles/polystyrene (AgNPs/PS) composite was further prepared by a reverse microemulsion polymerization method. The morphologies and structures of the AgNPs and the AgNPs/PS composite were characterized by UV‐visible spectroscopy (UV–vis), X‐ray diffraction (XRD), fourier transform infrared spectra (FTIR), and transmission electron microscopy (TEM). Furthermore, the molecular weight of the AgNPs/PS composite was measured by gel permeation chromatography (GPC), and the thermal stability of the AgNPs/PS composite was determined by thermal gravimetric (TG) analysis. Results show that the AgNPs have a particle size of 3–10 nm, and are almost spherical, uniform, and monodisperse both in a AgNPs colloid and in the AgNPs/PS composite. There are no characteristic peaks of silver oxide in the synthetic AgNPs and AgNPs/PS composite. The AgNPs/PS composite has a better thermal stability and a higher molecular weight than virgin PS. POLYM. COMPOS., 35:1325–1329, 2014. © 2013 Society of Plastics Engineers     

Influence of water addition on the structure of plasma-deposited allyl alcohol polymer films

One hundred and fifty nanometre thick polymer films made of allyl alcohol and H₂O addition were deposited onto aluminium substrates using the radio-frequency (rf) pulsed plasma mode. The structure–property relationships of polymer films were studied in dependence on the precursor ratio allyl alcohol-water. Both the regularity of structure and composition of such thin films in comparison to chemically polymerized allyl alcohol were investigated using by bulk-sensitive Fourier transform infrared spectroscopy (FTIR) in the spectral range of 4000–500 cm^?1 as well as surface-sensitive X-ray photoelectron spectroscopy (XPS). The intention of this work was to increase the yield in OH groups by addition of water to the allyl alcohol precursor. For an unambiguous identification of the functionality of the deposited films, the OH groups were labelled with trifluoroacetic anhydride and subsequently measured by XPS as well as quantitatively by FTIR. As expected, the O/C ratio grew with increasing water admixture by oxidation of both the plasma polymerized allyl alcohol layer to preferably aldehyde and/or carboxylic acid groups. In contrary, the concentration of OH groups in the deposited polymer film decreases dramatically with increasing admixture of water to the allyl alcohol plasma. It has been shown that the additional water has produced preferably higher oxidized C-O_x species with two or three C–O bonds. This fits also very well with the observation that almost no deuterium is introduced into the surface of plasma polymer if D₂O was added instead of H₂O.     

Properties and antimicrobial efficacy of cellulose fiber coated with silver nanoparticles and 3‐mercaptopropyltrimethoxysilane (3‐MPTMS)

Silver nanoparticles were coated onto cotton fabrics with 3‐mercaptopropyltrimethoxysilane (3‐MPTMS). The coating process was accomplished by soaking the cotton fabrics into silver colloid/3‐MPTMS solution at 43°C for 90 min. The coated fabrics were characterized by scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). SEM images showed a layer of silver nanoparticles and 3‐MPTMS on cotton. The XPS data showed that distinguishable binding energy peaks of Ag 3d, Si 2p, Si 2s, S 2p were 368/374, 102, 153, and 162 eV, respectively, which confirms the existence of silver and 3‐MPTMS on cotton fabrics. The treated cotton fabrics showed prominent antimicrobial effectiveness against Staphylococcus aureus (ATCC 6538) and Klebsiella pneumonia (ATCC 4352). Furthermore, the laundry test showed that 66% of silver nanoparticles were retained after five washing cycles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Facile polyacrylamide graft based on poly (2-chloroaniline) silver nano-composites as antimicrobial

Series of polymers based on the grafting of polyacrylamide with both poly(2-methoxyaniline) P2-MeOANI and poly(2-chloroaniline) P2-ClANI were synthesized by the oxidative chemical grafting copolymerization of individually 2-methoxyaniline (2-MeOANI) and 2-chloroaniline (2-ClANI) onto polyacrylamide (PACM). The grafting was performed in aqueous hydrochloric acid solution (HCl) using ammonium persulfate (APS) as oxidant. The optimum conditions of the grafting based on the yield was achieved. The obtained polymer samples at optimum conditions were assembling on colloidal silver nanoparticles (AgNPs). The obtained polymer samples and their AgNPs were characterized by UV- visible & IR spectroscopy, EM, TEM & TGA to confirm the suggested structure of obtained polymers. The efficiency of the prepared polymeric samples to using as anti-microbial including as sulfate reducing bacteria (SRB) was investigated.     

Growth and characterization of fluorocarbon thin films grown from trifluoromethane (CHF3) using pulsed‐plasma enhanced CVD

Trifluoromethane (CHF₃) was used as a precursor gas in pulsed‐plasma enhanced CVD to deposit fluorocarbon films onto Si substrates. The film composition, as measured by X‐ray photoelectron spectroscopy (XPS) of the C1s peak, was observed to change as the plasma duty cycle was changed by varying the plasma off‐time; this offers a route to control the molecular architecture of deposited films. FTIR results indicate that the film is primarily composed of CF_x components, with little or no C H incorporation into the film. The rms roughness of the films is extremely low, approaching that of the Si substrate; the low growth rate and consequent high‐power input/thickness is believed to be partly responsible. CHF₃ produces films with higher % CF₂ compared to other hydrofluorocompound (HFC) monomers (CH₂F₂ and C₂H₂F₄). However, the deposition kinetics for all three HFC gases display similar trends. In particular, at a fixed on‐time of 10 ms, the deposition rate per pulse cycle reaches a maximum at an off‐time of approximately 100 ms. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 842–849, 2000