Preparation and antibacterial effects of PVA‐PVP hydrogels containing silver nanoparticles

The poly(vinyl alcohol)/poly(N‐vinyl pyrrolidone) (PVA–PVP) hydrogels containing silver nanoparticles were prepared by repeated freezing–thawing treatment. The silver content in the solid composition was in the range of 0.1–1.0 wt %, the silver particle size was from 20 to 100 nm, and the weight ratio of PVA to PVP was 70 : 30. The influence of silver nanoparticles on the properties of PVA–PVP matrix was investigated by differential scanning calorimeter, infrared spectroscopy and UV–vis spectroscopy, using PVA–PVP films containing silver particles as a model. The morphology of freeze‐dried PVA–PVP hydrogel matrix and dispersion of the silver nanoparticles in the matrix was examined by scanning electron microscopy. It was found that a three‐dimensional structure was formed during the process of freezing–thawing treatment and no serious aggregation of the silver nanoparticles occurred. Water absorption properties, release of silver ions from the hydrogels and the antibacterial effects of the hydrogels against Escherichia coli and Staphylococcus aureus were examined too. It was proved that the nanosilver‐containing hydrogels had an excellent antibacterial ability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 125–133, 2007     

Fumed SiO2 nanoparticle reinforced biopolymer blend nanocomposites with high dielectric constant and low dielectric loss for flexible organic electronics

In the present study, fumed silica (SiO₂) nanoparticle reinforced poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP) blend nanocomposite films were prepared via a simple solution‐blending technique. Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to elucidate the successful incorporation of SiO₂ nanoparticles in the PVA/PVP blend matrix. A thermogravimetric analyzer was used to evaluate the thermal stability of the nanocomposites. The dielectric properties such as dielectric constant (?) and dielectric loss (tan δ) of the PVA/PVP/SiO₂ nanocomposite films were evaluated in the broadband frequency range of 10^?2 Hz to 20 MHz and for temperatures in the range 40–150 °C. The FTIR and UV–vis spectroscopy results implied the presence of hydrogen bonding interaction between SiO₂ and the PVA/PVP blend matrix. The XRD and SEM results revealed that SiO₂ nanoparticles were uniformly dispersed in the PVA/PVP blend matrix. The dielectric property analysis revealed that the dielectric constant values of the nanocomposites are higher than those of PVA/PVP blends. The maximum dielectric constant and the dielectric loss were 125 (10^?2 Hz, 150 °C) and 1.1 (10^?2 Hz, 70 °C), respectively, for PVA/PVP/SiO₂ nanocomposites with 25 wt % SiO₂ content. These results enable the preparation of dielectric nanocomposites using a facile solution‐casting method that exhibit the desirable dielectric performance for flexible organic electronics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44427.     

Enhancement of pervaporation performance of composite membranes through in situ generation of silver nanoparticles in poly(vinyl alcohol) matrix

Composite membranes were prepared from an aqueous solution of poly(vinyl alcohol) (PVA) and silver sulphate. The silver nanoparticles were generated in situ before crosslinking PVA matrix by reduction of silver ions using sodium borohydride. Physico‐chemical properties of the resulting composite membranes were studied using Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy (UV–vis), thermogravimetric analysis (TGA), Wide‐angle X‐ray diffraction (WAXD), scanning electron microscopy (SEM), and universal testing machine (UTM). The UV–vis spectrum shows a single peak at 410 nm due to surface plasmon absorption of silver nanoparticles. This surely specified that silver nanoparticles are generated in PVA matrix. The membranes were under go pervaporation (PV) for separation of water from isopropanol at different temperatures. The results indicated that hydrophilicity and amorphous nature of the membranes were increased with increasing silver nanoparticles in PVA matrix. The swelling and separation performance of the membranes were studied. Both permeation flux and separation factor were increased with increasing silver nanoparticles in PVA matrix. The results showed that the membrane containing 2.5 mass% of Ag salt exhibited excellent PV performance. The values of total flux and flux of water are almost closed to each other, indicating that membranes could be effectively used to break the azeotropic point of water‐isopropanol. The long‐term test was performed at room temperature and ascertained that membranes were durable up to 30 days for the dehydration of IPA. On the basis of the estimate Arrhenius activation energy values, the efficiency of the membranes was discussed. The calculated ΔH_s values are negative for all the membranes, indicating that Longmuir's mode of sorption is predominant. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41248.     

Radiation synthesis and characterization of polyvinyl alcohol/chitosan/silver nanocomposite membranes: antimicrobial and blood compatibility studies

Polyvinyl alcohol/chitosan/silver (PVA/CS/Ag) nanocomposite membranes were synthesized by γ-radiation with promising antimicrobial and biomedical applications. The nanocomposite membranes were prepared by mixing PVA and CS solutions with different copolymer compositions in the presence of silver nitrate (AgNO₃) and glutaraldehyde as cross-linker, followed by in situ reduction with γ-radiation at different doses. The nanocomposite membranes were characterized by ultraviolet spectroscopy (UV), Fourier transform infrared, X-ray diffraction (XRD) and transmission electron microscopy (TEM). UV studies showed a strong peak around λ _max at 430 nm due to surface plasmon resonance of silver nanoparticles formed during irradiation. As the irradiation dose increased from 25 to 75 kGy, the plasmon band is shifted from 430 to 418 nm with high intensity, indicating the formation of smaller particles. TEM investigation showed uniform distribution of silver nanoparticles (AgNPs) in the membranes with mean diameter of 32–19 nm. XRD results confirmed that the mean diameter of AgNPs estimated from the Debye–Scherrer formula was in the range of 27.5–12.8 nm which confirms the TEM results. The PVA/CS/Ag nanocomposite membranes exhibited good antibacterial activity and were found to cause significant reduction in microbial growth. The nanocomposite membranes showed non-thrombogenicity effect and slightly haemolytic potential, suggesting their promising use in biomedical applications.     

Preparation and characterization of electrospun poly(ε‐caprolactone)/poly(vinyl pyrrolidone) nanofiber composites containing silver particles

A nanofiber membrane composed of poly(ε‐caprolactone) (PCL), poly(vinyl pyrrolidone) (PVP), and silver nanoparticles was prepared via electrospinning technique. The morphology and structure of the PCL/PVP/Ag nanofibers composite were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). The SEM images showed that various composites of PCL/PVP/Ag could be electrospun to yield continuous and uniform nanofibers. FTIR spectra indicated that the molecular interactions between PCL and PVP are weak. The hydrophilicity, mechanical property, and swelling behavior of the as‐spun composites can be manipulated by altering the blend ratio of PCL/PVP. XRD patterns and XPS spectra showed that the Ag nanoparticles were dispersed in the PCL/PVP nanofiber composites; and the Ag nanoparticles endowed the PCL/PVP/Ag composite with antibacterial activities. The obtained PCL/PVP/Ag nanofiber composites with the morphology similar to that of native extracellular matrix have the potential to create a moist environment and to kill bacteria, which make it possible to be used for wound dressing application. POLYM. COMPOS., 37:2847–2854, 2016. © 2015 Society of Plastics Engineers     

Perturbation-correlation moving-window two-dimensional correlation spectroscopic studies on the heat treatment of poly(vinyl alcohol)/silver nitrate film

In this paper, poly(vinyl alcohol)/silver nitrate (PVA/AgNO₃) films were annealed at 180 °C for 1 h to prepare highly electrically conductive poly(vinyl alcohol)/silver (PVA/Ag) nanohybrids. Ultraviolet (UV)-visible absorption spectra, X-ray diffraction (XRD) scans, and scanning electronic microscopy (SEM) were applied to investigate the structures and morphology of the PVA hybrids. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to study the thermal property of PVA/AgNO₃ films. Furthermore, perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy combined with temperature-dependent Fourier transform infrared (FTIR) spectroscopy was used to investigate the conversion of AgNO₃ into Ag nanoparticles in PVA matrix. The results show that the chelates for AgNO₃ coordinated with hydroxyl groups are primarily decomposed in the temperature regions of 39.7–72.6 °C and 182.7–199.6 °C. AgNO₃ is reduced into Ag⁰ and the hydroxyl groups of PVA are oxidized into carbonyl groups. The PVA-AgNO₃ chelates are very rapidly decomposed in the temperature region of 182.7–199.6 °C. Large amounts of Ag⁰ produced by the reduction of AgNO₃ are aggregated into Ag nanoparticles which are homogeneously dispersed into the PVA matrix. When the temperature increases to 212.7 °C, the unhydrolyzed acetate groups in PVA chains are sharply decomposed.     

Radiation synthesis and characterization of poly(vinyl alcohol)/poly(N-vinyl-2-pyrrolidone) based hydrogels containing silver nanoparticles

A series of PVA/PVP based hydrogels at different compositions were prepared by gamma irradiation. The gel fraction degree of swelling were investigated. Highly stable and uniformly distributed silver nanoparticles have been obtained onto hydrogel networks. The morphology and structure of (PVA/PVP) hydrogel and dispersion of the silver nanoparticles in the polymeric matrix were examined by scanning electron microscopy (SEM) and infrared spectroscopy (FT-IR), respectively. The formation of silver nanoparticles has been confirmed by ultraviolet visible (UV–vis) spectroscopy. A strong characteristic absorption peak was found to be around 420 nm for the silver nanoparticles in the hydrogel nanocomposite. The X-ray diffraction pattern confirmed the formation of silver nanoparticles with average particle size of 12 nm. The diameter distribution of silver nanoparticles was determined by dynamic light scattering DLS. Transmission electron microscope (TEM) showed almost spherical and uniform distribution of silver nanoparticles through the hydrogel network and the mean size of silver nanoparticles ranging is 23 nm. The good swelling properties and antibacterial of PVA/PVP-Ag hydrogel suggest that it can be a good candidate as wound dressing.     

Formation of silver nanoparticles created in situ in an amphiphilic block copolymer film

In this work, silver nanoparticles were synthesized with an amphiphilic diblock copolymer, polystyrene‐block‐poly(1‐vinyl‐2‐pyrrolidone) (PS‐b‐PVP), as a template film. First, microphase‐separated amphiphilic PS‐b‐PVP (70 : 30 wt %) was synthesized through atom transfer radical polymerization. The self‐assembled block copolymer film was used to template the growth of silver nanoparticles by the introduction of a silver trifluoromethanesulfonate precursor and an ultraviolet irradiation process. The in situ formation of silver nanoparticles with an average size of 4–6 nm within the block copolymer template film was confirmed with transmission electron microscopy, ultraviolet–visible spectroscopy, and wide‐angle X‐ray scattering. Fourier transform infrared spectroscopy also demonstrated the selective incorporation and in situ formation of silver nanoparticles within the hydrophilic poly(1‐vinyl‐2‐pyrrolidone) domains, which were mostly due to the stronger interaction strength of the silver with the carbonyl oxygens of poly(1‐vinyl‐2‐pyrrolidone) in the block copolymer. This work provides a simple route for the in situ synthesis of silver nanoparticles within a polymer film. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Thermal and spectroscopic studies of poly(N‐vinyl pyrrolidone)/poly(vinyl alcohol) blend films

Poly(N‐vinyl pyrrolidone) (PVP) and poly (vinyl alcohol) (PVA) homopolymers and their blended samples with different compositions were prepared using cast technique and subjected to X‐ray diffraction (XRD) measurements, infrared (IR) spectroscopy, ultraviolet/visible spectroscopy, and thermogravimetric analysis (TGA). XRD patterns of homopolymers and their blended samples indicated that blending amorphous materials, such as PVP, with semicrystalline polymer, such as PVA, gives rise to an amorphous structure with two halo peaks at positions identical to those found in pure PVP. Identification of structure and assignments of the most evident IR ‐ absorption bands of PVP and PVA as well as their blends in the range 400–2000 cm^?1 were studied. UV–vis spectra were used to study absorption spectra and estimate the values of absorption edge, E_g, and band tail, E_e, for all samples. Making use of Coats‐Redfern relation, thermogravimetric (TG) data allowed the calculation of the values of some thermodynamic parameters, such as activation energy E, entropy ΔS^#, enthalpy ΔH, and free energy of activation ΔG^# for different decomposition steps in the samples under investigation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poly(vinyl alcohol)‐g‐lactic acid copolymers and films with silver nanoparticles

Poly(vinyl alcohol) (PVA), a well‐known synthetic biodegradable, biocompatible, and hydrophilic polymer is susceptible to several structural modifications, due to the presence of hydroxyl groups in its backbone. PVA was grafted with L (+)‐lactic acid (LA) in molar ratios VA/LA (1/1, 1.5/1, and 2.2/1), manganese acetate as catalyst, by solution polycondensation procedure, resulting the poly(vinyl alcohol)‐g‐lactic acid copolymers. Aqueous solutions of copolymers with glycerol as plasticizer, silver nanoparticles (Ag^o), and sodium tetraborate as crosslinking agent were used for films casting. The copolymers were characterized by FTIR and ¹H RMN spectroscopy, gel permeation chromatography, thermal analyses (DTG and DSC), silver particles size, while films were characterized by mechanical properties and mechanodynamic analyses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electron Beam Synthesis and Characterization of Poly Vinyl Alcohol/Poly Acrylic Acid Embedded Ni and Ag Nanoparticles

Electron beam irradiation was applied to prepare poly (vinyl alcohol) and poly (acrylic acid) P (PVA/AAc) containing nickel and silver nanoparticles. The prepared P (PVA/AAc)–Ni and P (PVA/AAc)–Ag nanoparticles were characterized by Fourier-transform infrared, UV–Visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscope (TEM). The electrical conductivity and thermal gravimetrical analysis (TGA) have been investigated. Bacterial sensitivity toward nickel and silver nanoparticles was studied. The XRD and TEM confirmed that by increasing the Ni or Ag contents from 10 to 150?mmol in the copolymers, the metal particle size increases from 27.6 to 45.6?nm for Ni and from 14.8 to 37.4?nm for Ag. Meanwhile, the mean size particle increases from 33.02 to 45.05?nm for Ni and from 15.5 to 44.03?nm for Ag. The electrical conductivity of the polymer containing Ag is higher than that of Ni and it increased by increasing the metal content. The TGA studies confirmed that, the thermal stability increase by the introduction of metal into polymeric complex. Bacterial sensitivity to metal nanoparticles was found to vary depending on the microbial species. Disc diffusion studies with P. aeruginosa, E. coli and K. pneumoniae revealed greater effectiveness of the silver nanoparticles compared to the nickel nanoparticles, S. aureus depicted the highest sensitivity to nanoparticles compared to the other strains and was more adversely affected by the nickel nanoparticles.     

Preparation and characterization by radiation of hydrogels of PVA and PVP containing Aloe vera

In these studies, hydrogels for wound dressing were made from a mixture of Aloe vera, poly(vinyl alcohol) (PVA) and poly(N‐vinylpyrrolidone) (PVP) by freeze‐thaw, gamma‐ray irradiation, or a two‐step process of freeze‐thaw and gamma‐ray irradiation. Physical properties, such as gelation, water absorptivity, gel strength and degree of water evaporation were examined to evaluate the applicability of these hydrogels to wound dressing. The PVA:PVP ratio was 6:4, and the dry weight of Aloe vera was in the range of 0.4‐1.2 wt %. The solid concentration of PVA/PVP/Aloe vera solution was 15 wt %. Mixtures of PVA/PVP/Aloe vera were exposed to gamma irradiation doses of 25, 35 and 50 kGy to evaluate the effect of irradiation dose on the physical properties of the hydrogels. Gel content and gel strength increased as the concentration of Aloe vera in PVA/PVP/Aloe vera decreased and as irradiation dose increased and freeze‐thaw was repeated. Swelling degree was inversely proportional to gel content and gel strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1612–1618, 2004     

Ultraviolet‐induced crosslinking of poly(vinyl alcohol) evaluated by principal component analysis of FTIR spectra

The crosslinking of poly(vinyl alcohol) (PVA) films under ultraviolet irradiation for between 1 and 4 h was studied in air at 25 °C in the presence of sodium benzoate by Fourier‐transform infrared spectroscopy (FTIR) using the attenuated total reflectance technique (ATR). Principal component analysis (PCA) is a mathematical procedure that allows treatment of the entire infrared spectrum and is very appropriate for analysing the chemical modifications initiated by sodium benzoate which occur in PVA upon UV irradiation. By PCA it was possible to clarify the mechanism of crosslinking of PVA. From this FTIR–PCA study, it is suggested that a free radical arising from the photolysis of sensitizer would abstract a tertiary hydrogen atom from the polymer chain to yield a polymeric radical. This radical reacts with O? H groups, leading to the formation of ether bonds between the polymeric chains and hence to crosslinking and insolubilization of the PVA. © 2001 Society of Chemical Industry     

Preparation,characterization, electrical and antibacterial properties of sericin/poly(vinyl alcohol)/poly(vinyl pyrrolidone) composites

In this study, we focused on the fabrication of poly(vinyl alcohol) (PVA)/poly(vinyl pyrrolidone) (PVP)/sericin composites via a simple solution‐blending method. The composites were characterized by Fourier transform infrared (FTIR) spectroscopy, UV spectroscopy, X‐ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry, thermogravimetric analysis (TGA), and measurements of the conductivity, tensile strength, and antibacterial activity against Staphylococcus aureus. The results of FTIR and UV spectroscopy implied the occurrence of hydrogen bonding between sericin and the PVA/PVP blend. The structure and morphology, studied by XRD and SEM, revealed that the sericin particles were well dispersed and arranged in an orderly fashion in the blend. The glass‐transition temperature (T_g) of the composite was higher than that of the pure blend, and the T_g value shifted toward higher temperatures when the volume fraction of sericin increased. TGA indicated that sericin retarded the thermal degradation; this depended on the filler concentration. The mechanical and electrical properties, such as the tensile strength, alternating‐current electrical conductivity, dielectric constant, and dielectric loss of the composites, were higher than those of the pure blend, and these properties were enhanced when the concentration of sericin was increased up to 10 wt % filler content, whereas the elongation at break of the composite decreased with the addition of sericin particles. The antibacterial properties of the composite showed that sericin had a significant inhibitory effect against S. aureus. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43535.     

Studies of chitosan. I. Preparation and characterization of chitosan/poly(vinyl alcohol) blend films

Various blending ratios of chitosan/poly (vinyl alcohol) (CS/PVA) blend films were prepared by solution blend method in this study. The thermal properties and chemical structure characterization of the CS/PVA blend films were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and Fourier transform infrared (FTIR). Based upon the observation on the DSC thermal analysis, the melting point of PVA is decreased when the amount of CS in the blend film is increased. The FTIR absorption characteristic is changed when the amount of CS in the blend film is varied. Results of X‐ray diffraction (XRD) analysis indicate that the intensity of diffraction peak at 19° of PVA becomes lower and broader with increasing the amount of CS in the CS/PVA blend film. This trend illustrates that the existence of CS decreases the crystallinity of PVA. Although both PVA and CS are hydrophilic biodegradable polymers, the results of water contact angle measurement are still shown as high as 68° and 83° for PVA and for CS films, respectively. A minimum water contact angle (56°) was observed when the blend film contains 50 wt % CS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation and antibacterial activity of polyvinyl alcohol/regenerated silk fibroin composite fibers containing Ag nanoparticles

Polyvinyl alcohol (PVA)/regenerated silk fibroin (SF)/AgNO₃ composite nanofibers were prepared by electrospinning. A large number of nanoparticles containing silver were generated in situ and well‐dispersed nanoparticles were confirmed by transmission electron microscopy (TEM) intuitionally. Ultraviolet (UV)‐visible spectroscopy and X‐ray diffraction (XRD) patterns indicated that nanoparticles containing Ag were present both in blend solution and in composite nanofibers after heat treatment and after subsequent UV irradiation. By annealing the nanofibers, Ag⁺ therein was reduced so as to produce nanoparticles containing silver. By combining heat treatment with UV irradiation, Ag⁺ was transformed into Ag clusters and further oxidized into Ag₃O₄ and Ag₂O₂. Especially size of the nanoparticles increased with heat treatment and subsequent UV irradiation. This indicated that the nanoparticles containing silver could be regulated by heat treatment and UV irradiation. The antimicrobial activity of heat‐treated composite nanofibers was evaluated by Halo test method and the resultant nanofibers showed very strong antimicrobial activity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of poly(vinyl alcohol) cryogel‐silver nanocomposites and evaluation of blood compatibility,cytotoxicity, and antimicrobial behaviors

In this investigation, cryogels composed of poly(vinyl alcohol) (PVA) were prepared by repeated freeze‐thaw method. The prepared cryogels served as templates for producing highly stable and uniformly distributed silver nanoparticles via in situ reduction of silver nitrate (AgNO₃) using alkaline formaldehyde solution as reducing agent. The structure of the PVA/Ag cryogel nanocomposites was characterized by a Fourier transform infrared and Raman spectroscopy. The morphologies of pure PVA cryogels and PVA/Ag nanocomposites were observed by a scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The SEM analysis suggested that cryogels show a well defined porous morphology whereas TEM micrographs revealed the presence of nearly spherical and well separated Ag nanoparticles with diameter about 100 nm. XRD results showed all relevant Bragg's reflections for crystal structure of silver nanoparticles. The amount of silver in cryogel nanocomposites and thermal stability were determined by inductively coupled plasma atomic emission spectrometry (ICP‐AES) and thermogravimetric analysis measurements. Mechanical properties of nanocomposites were observed in terms of tensile strength. The antibacterial studies of the synthesized nanosilver containing cryogels showed good antibacterial activity against both gram‐negative and gram‐positive bacteria. The prepared PVA/Ag nanocomposites were also investigated for swelling and deswelling behaviors. The results reveal that both the swelling and deswelling process depends on the chemical composition of the cryogel silver nanocomposites, number of freeze‐Thaw cycles and pH and temperature of the swelling medium. The biocompatibility of the prepared nanocomposites was judged by in vitro methods of percent hemolysis and protein (BSA) adsorption. POLYM. COMPOS., 36:1983–1997, 2015. © 2014 Society of Plastics Engineer     

Preparation of hydrophobic polymer particles by radical polymerization and subsequent modification into magnetically doped particles

The application potential of hydrophobic polymer is numerous. Lauryl methacrylate (LMA) having long alkyl chain is a commercially available hydrophobic monomer. In this investigation, poly‐LMA (PLMA) latex particles were prepared by suspension polymerization in aqueous media using 2,2′‐azobis(isobutyronitrile) (AIBN) in presence of poly(vinyl alcohol) (PVA) as steric stabilizer. The preparation kinetics was studied in detail in terms of percentage yield and particle size variation. Low glass transition temperature (～ ?65°C) associated with high flexibility did not allow electron micrographic observation though ¹H‐NMR and particle size measurement confirmed the formation of PLMA latex. To improve the glass transition temperature, aqueous emulsion copolymerization of LMA with methyl methacrylate (MMA) was carried out. The solubility of LMA was improved by adding ethanol to the aqueous phase. Two types of polymeric stabilizers, PVA and poly(vinyl pyrrolidone) (PVP) were used to stabilize the colloidal particles. The nature of the stabilizer affected both morphology and final rate of polymerization. The hydrophobic P(LMA‐MMA) copolymer particles were subsequently modified by nanosized magnetic (Fe₃O₄) particles by two different methods. The in situ formation of Fe₃O₄ particles in presence of P(LMA‐MMA) was found to be suitable for the preparation of magnetic latex particles. Scanning electron microscope (SEM), FTIR, transmission electron microscope (TEM), X‐ray diffraction (XRD) and energy‐dispersive X‐ray spectroscopy (EDX) were used for the characterization of magnetically doped particles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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.     

Swollen behavior of crosslinked network hydrogels based on poly(vinyl alcohol) and polydimethylsiloxane

Poly(vinyl alcohol) (PVA) was dissolved in the water to make a 10 wt % aqueous solution, and polydimethylsiloxane (PDMS) was mixed with 1 wt % 2,2‐dimethyl‐2‐phenylacetophenone (DMPAP) and 0.5 mol % methylenebisacrylamide (MBAAm) in isopropyl alcohol. This mixture was added to a PVA aqueous solution and heated at 90°C for 7 h. Various crosslinked networks were prepared at different molar ratios of PVA/PDMS (1:1, 1:3, and 3:1). The characterization of PVA/PDMS crosslinked networks was determined by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), a universal testing machine (UTM), and the equilibrium water content (EWC). The DSC melting endotherms showed, at 219.49°C, a sharp endothermic peak of PVA, and PVA/PDMS crosslinked networks had melting peaks close to this point. The value of EWC increased with the content of PVA in the crosslinked networks, simultaneously depending on the temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 957–964, 2002