Electrospinning and characterization of poly(vinyl alcohol)/chitosan oligosaccharide/clay nanocomposite nanofibers in aqueous solutions

Submicron fibers of the composite of poly(vinyl alcohol) (PVA), chitosan oligosaccharide [COS, (1→4)2-amino-2-deoxy-β-d-glucose], and montmorillonite clay (MMT) were prepared using electrospinning method with aqueous solutions. Scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), thermal gravimetric analyzer, and tensile strength testing machine (Zwick) were utilized to characterize the PVA/COS/MMT nanofiber mats morphology and properties. The PVA/COS ratio and MMT concentration play important roles in nanofiber mat properties. XRD and TEM data demonstrated that exfoliated MMT layers were well-distributed within nanofiber. It was also found that the mechanical property and thermal stability were increased with COS and MMT contents.     

Preparation and characterization of polyvinyl alcohol/β‐cyclodextrin/GO‐Ag nanocomposite with improved antibacterial and strength properties

In this work, new hydrogel films based on polyvinyl alcohol (PVA) and β‐cyclodextrin (β‐CD) were prepared with the aim of studying their ability as an antibacterial and drug carrier system. Gallic acid (GA) was used as an antibacterial drug which was encapsulated into the β‐CD cavity, and finally, β‐CD inclusion complex (GA/βCD‐IC) was prepared. On the other hand, silver nanoparticles (AgNPs) were synthesized on the graphene oxide (GO) surface (GO‐Ag), and the obtained GO‐Ag was used to enhance the antibacterial properties and mechanical strength of their films. FT‐IR and DSC analysis approved the formation of cross‐linking with glutaraldehyde between the PVA and β‐CD. Hydrogel films were characterized using XRD and SEM. The disc diffusion method showed the antibacterial activity for the films containing GO‐Ag and GA. Due to the good strength, elasticity, WVP, and swelling ability, PVA/GA/βCD‐IC/GO‐Ag can be proposed as a potential antibacterial drug delivery system.     

Ag nanoparticle-embedded one-dimensional β-CD/PVP composite nanofibers prepared via electrospinning for use in antibacterial material

Ag nanoparticle-embedded one-dimensional β-CD (β-cyclodextrin)/PVP composite nanofibers were prepared using a one-step electrospinning technique. Ag nanoparticles were obtained in the AgNO₃/β-CD/DMF solution, in which silver nitrate been introduced as the precursor, DMF as solvent, β-CD as reducing and capping agent. After electrospinning of the composite solution at room temperature, the β-CD/PVP nanofibers containing Ag nanoparticles were obtained. The electrospun composite solution containning Ag nsnopsrticles were confirmed by UV-visible absorption spectra; the resulting composite nanofibers were characterized by scanning electron microscopy , transmission electron microscopy, and X-ray diffraction. Ag-β-CD/PVP nanofiber exhibits good antibacterial property for Escherichia coli and Staphylococcus aureus. Consequently, we propose that these Ag nanoparticle-embedded 1D-nanostructures prepared via electrospinning may be used as antibacterial material.     

Synthesis,characterization and antibacterial properties of a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag

In this study, a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag (PANI/PVA/Ag) has been successfully synthesized. The chemical reduction method was used to produce Ag nanoparticle colloidal solution from Ag⁺ ions. The polymerization of aniline occurred in situ for the preparation of polyaniline (PANI) in the presence of ammonium persulfate. With exposure to Ag nanoparticles on the PANI/PVA composite, a new nanocomposite was obtained. The morphology and particle size of the novel nanocomposite was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) analyses. According to XRD analysis, the size of nanoparticles was found to be in the range of 10–17 nm. SEM images showed the favored shape of nanoparticles as triangle which is a benign shape for antibacterial analysis. The antibacterial activity of the obtained nanocomposite was also evaluated against Gram positive bacteria Staphylococcus aureus (Staph. aureus) and Gram negative Escherichia coli (E. coli) using the paper disk diffusion method. The antibacterial study showed that the PANI/PVA composite did not have a very good antibacterial activity but PANI/PVA/Ag nanocomposites were found to be effective against two bacteria.     

Preparation of Silver Nanoparticles Incorporated Electrospun Polyurethane Nano-fibrous Mat for Wound Dressing

Polyurethane foam is currently used as an exudate absorptive wound dressing material. In this study silver (Ag) nanoparticles were incorporated into electrospun polyurethane (PU) nanofiber to enhance the antibacterial as well as wound healing properties. The electrospinning parameters were optimized for PU with and without silver nanoparticles. Silver nanoparticles were synthesized by aqueous and organic methods. The water absorption, antibacterial and cytocompatibility of the PU-Ag nanofibers were studied and compared to that of conventional PU foam. The results indicated that the PU-Ag nanofibers could be used for wound dressing applications.     

Effect of pullulan/poly(vinyl alcohol) blend system on the montmorillonite structure with property characterization of electrospun pullulan/poly(vinyl alcohol)/montmorillonite nanofibers

Nanofibers of the composite of pullulan (PULL), poly(vinyl alcohol) (PVA), and montmorillonite clay (MMT) were prepared using electrospinning method in aqueous solutions. Pullulan is an interesting natural polymer for many of its merits and good properties. Because of biocompatibility and non-toxicity of PVA, it could be used in numerous fields. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were done to characterize the PULL/PVA/MMT nanofibers morphology and properties. XRD patterns and FTIR data demonstrated that there were good interactions between PULL and PVA caused by possibly hydrogen bonds. Moreover, XRD data and TEM images indicated that intercalated and exfoliated MMT nanoplatelets can be obtained within the PULL/PVA/MMT nanofibers depending on the PULL/PVA blend ratios. Furthermore, the thermal stability and mechanical property (tensile strength) of PULL/PVA/MMT nanofibers could be enhanced more by exfoliated MMT nanoplatelets than intercalated structures of that nanoplatelets.     

An optimistic approach “from hydrophobic to super hydrophilic nanofibers” for enhanced absorption properties

Water holding capacity becomes essential for hygiene applications including baby diapers. Microfibers of hydrophilic polymers have been useful source for such applications. While, super hydrophilic and stable nanofibers incorporation with functional antibacterial agent are essential to get higher absorption of water along with antimicrobial activity against harmful bacteria. In current work, hydrophobic polymeric nanofibers are transformed to super hydrophilic nanofibers by addition of copper (II) oxide (CuO hereafter) nanoparticles. CuO nanoparticles provided two distinctive properties to existing nanofibers. Firstly, nanofibers surface area was significantly increased, and secondly copper (II) oxide itself is hydrophilic material which imparted hydrophilicity to base polymer. Polyacrylonitrile, crosslinked Polyvinyl Alcohol, and PICT were selected as super hydrophobic polymeric nanofibers. Copper II oxide nanoparticles (same concentration) were added in all polymer solution and electrospun. Surface, morphological, and hydrophilic properties were characterized and it was concluded that copper II oxide is suitable for transforming hydrophobic nanofibers to super hydrophilic nanofibers. Water holding capacity (WHC) was also improved for all prepared nanofiber mats. WHC for PVA/CuO, PAN/CuO, and PICT/CuO were recorded an average of 23 g/g, 21 g/g, and 18 g/g respectively. Combining all useful results from possible characterization of nanofiber mats, it is expected that CuO nanoparticles loaded nanofibers will have potential application as antibacterial, sustainable, and stable replacement of hygiene products.     

Natural rubber/clay nanocomposites: Influence of poly(ethylene glycol) on the silicate dispersion and local chain order of rubber network

A novel preparation of natural rubber (NR)/Na⁺-montmorillonite (MMT) nanocomposites in only one step by using poly(ethylene glycol) (PEG) has been investigated. PEG behaves as dispersing agent favouring the intercalation of rubber chains into the silicate galleries and providing substantially improved clay dispersion. Intercalated/exfoliated miscible hybrids were observed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The influence of PEG on the network structure has also been evaluated by static proton double-quantum nuclear magnetic resonance spectroscopy (¹H DQ NMR) at low-field. Silicate nanoparticles with a high aspect ratio (clay tactoids) and a more crosslinked rubber network have been obtained for an optimum PEG/MMT ratio. Both effects were responsible of the enhancement on mechanical properties.     

Preparation of Polymer Nanofibers Containing Silver Nanoparticles by Using Poly(N‐vinylpyrrolidone)

Summary: Poly(N‐vinylpyrrolidone) (PVP) was used in two methods to prepare polymer nanofibers containing Ag nanoparticles. The first method involved electrospinning the PVP nanofibers containing Ag nanoparticles directly from the PVP solutions containing the Ag nanoparticles. N,N‐Dimethylformamide was used as a solvent for the PVP as well as a reducing agent for the Ag⁺ ions in the PVP solutions. In the second method, poly(vinyl alcohol) (PVA) aqueous solutions were electrospun with 5 wt.‐% of the PVP containing Ag nanoparticles. The Ag nanoparticles were evenly distributed in the PVA nanofibers. PVP containing Ag nanoparticles could be used to introduce Ag nanoparticles to other polymer nanofibers that are miscible with PVP.

TEM image of a PVA nanofiber electrospun with 5 wt.‐% of the PVP containing Ag nanoparticles.     

Structure and rheology of aqueous poly(vinyl acetate) dispersions modified with montmorillonite

It has been shown that the rheological properties and resistance to sedimentation of aqueous poly(vinyl acetate) (PVA) latexes, which are used for the preparation of coatings and adhesives, can be controlled by adding sodium montmorillonite (MMT). The adding of MMT initiates gelation of the PVA dispersions, which manifests itself as the appearance of the yield stress, thixotropy, and viscoelasticity. X-ray diffraction analysis of the complex dispersions and films based on them has shown a transition from exfoliated to intercalated clay tactoids with an increase in their content. In view of the complex composition of the PVA latexes, which contain a stabilizer (poly(vinyl alcohol)) and a plasticizer (dibutyl phthalate), the components that are predominantly intercalated into the MMT interplanar space, have been identified. The highest yield stress and rigidity of the structural network, which arises in a sample as a result of the joint coagulation of PVA and MMT particles, are observed upon the incorporation of 1.2 wt % MMT into the latex.     

Preparation and characterization of silver-modified poly(vinyl alcohol)/polyethyleneimine hybrids as a chemical and biological protective material

Nanohybrid membranes based on the silver (Ag) and a poly(vinyl alcohol)/polyethyleneimine (PVA/PEI) blend were prepared by an in-situ reduction method, in which the silver nitrate, PVA and PEI acted as precursor, linker and polyamine reductant, respectively. The objective of the study was to develop and evaluate permeable membranes (PVA/PEI) impregnated with Ag nanoparticulates that can protect against simulants of chemical and biological warfare agents. The physical properties of the PVA/PEI-Ag hybrids were examined using SEM, TEM, TGA, and UV-vis spectroscopy, the results indicated that the Ag was incorporated in the PVA/PEI matrix after impregnation. The Ag content and surface morphology of the PVA/PEI-Ag hybrids depended on the initial concentration of AgNO₃. The chemical barrier properties against 2-chloroethyl-ethyl sulfide (CEES) were investigated based on static-diffusion method with gas chromatograph (GC). The antibacterial effects of the PVA/PEI-Ag hybrids were assessed by the zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and plate-counting methods. The results of this study showed that PVA/PEI-Ag hybrids that act against simulants of chemical and biological weapons while retaining their ability to transmit moisture vapor could be obtained.     

热塑性淀粉/聚乙烯醇/蒙脱土三元纳米复合材料

用熔融挤出的方法制备了甘油塑化热塑性淀粉（TPS）/聚乙烯醇（PVA）/蒙脱土（MMT）纳米复合材料,添加蒙脱土和聚乙烯醇用以提高热塑性淀粉材料的力学性能。 在相对湿度50%的条件下,复合材料的XRD衍射谱图和透射电子显微镜测试表明,MMT以剥离状态均匀分布在TPS/PVA基体中;力学测试表明,当MMT的质量分数从0％增至5％时,复合材料的力学性能明显提高。 当蒙脱土的质量分数为3%时,复合材料最大抗张强度达到13.24 MPa,杨氏模量达到61.46 MPa。 这说明蒙脱土在复合材料中可以起到物理交联点的作用,提高了复合材料的力学性能。     

Influence of the nanoparticle type on the thermal decomposition of the green starch/poly(vinyl alcohol)/montmorillonite nanocomposites

In this study, some aspects concerning the thermal decomposition of starch/poly(vinyl alcohol) (PVA)/montmorillonite (MMT) nanocomposites with 2 wt% nanoclay, prepared by melt mixing method, were studied. For these loadings, the inorganic fillers are well dispersed through the PVA/starch matrix, i.e., the nanocomposites formed are mostly intercalated hybrids. The aim of this article is to establish the effect of the nanofiller nature on the thermal decomposition of the starch/PVA/MMT nanocomposites. The thermal behavior of the 50 wt% starch/50 wt% PVA blend and its nanocomposites with 2 wt% nanoclay has been investigated by thermogravimetric analysis coupled with Fourier transform-infrared spectroscopy and mass spectrometry (MS). The volatile compounds resulting during the thermal degradation were studied by in situ vapor phase FT-IR spectroscopy and MS technique under a controlled temperature/time program. Apart from the identification of the volatile compounds, some conclusions on the nanoclays effect on the degradation mechanism and formation of the volatile compounds in accordance with the previously developed general mechanisms for PVA and starch degradation have been formulated. The clay–PVA/starch nanocomposites show completely different degradation product distribution patterns, which may be attributed to the presence of the head-to-head structures and Si–O–C linkages formed between clay and blend components.     

Highly efficient catalytic performances of nitro compounds via hierarchical PdNPs-loaded MXene/polymer nanocomposites synthesized through electrospinning strategy for wastewater treatment

The problem of water pollution has become increasingly serious,and it has already threatened the survival of mankind and has become an obstacle to the healthy development of human health.Here,we prepared a novel polyvinyl alcohol(PVA)/polyacrylic acid(PAA)/MXene fiber membrane by electrospinning.After heat treatment of film and subsequent modification with Pd nanoparticles,PVA/PAA/MXene@PdNPs composite nanofiber membrane with high specific surface area and excellent catalytic performance was finally prepared.The uniform distribution of MXene sheets in the composite fiber membrane not only solves the problem that the MXene sheet is not easy to be monolayerized,but also can grow the self-reduced Pd nanoparticles on the MXene sheets.In addition,the composite nanofiber membrane exhibits excellent catalytic ability and cycle stability for 4-nitrophenol(4-NP) and 2-nitrophenol(2-NA),providing new strategy for the study of catalytic composite materials related to degradation of wastewater.     

聚乙烯醇/氟基蒙脱土纳米复合材料的合成及性能研究

采用水热方法,在493 K条件下反应72小时,合成了氟基蒙脱土(F-MMT),在这种F-MMT中,硅酸盐结构中的一些OH-被F-取代。采用溶液插层方法,制备了聚乙烯醇/F-MMT纳米复合材料(PVA/F-MMT)。采用X 射线衍射、扫描电镜和透射电镜对F-MMT 和 PVA/F-MMT纳米复合材料进行了表征;结果表明,片状结构的F-MMT均匀分散于PVA中,形成了层离结构的纳米复合材料。热重分析、力学性能和紫外可见光谱的测试结果表明,在没有牺牲光学性能情况下,PVA/F-MMT纳米复合材料的热稳定性和力学性能都得到了提高。力学和热学性能的提高归功于F-MMT均匀而好的分散于聚合物基体中,以及PVA中的 OH- 和F-MMT 中F-之间强的氢键作用。     

Silver Nanoparticle-Anchored Human Hair Kerateine/PEO/PVA Nanofibers for Antibacterial Application and Cell Proliferation

The main core of wound treatment is cell growth and anti-infection. To accelerate the proliferation of fibroblasts in the wound and prevent wound infections, various strategies have been tried. It remains a challenge to obtain good cell proliferation and antibacterial effects. Here, human hair kerateine (HHK)/poly(ethylene oxide) (PEO)/poly(vinyl alcohol) (PVA) nanofibers were prepared using cysteine-rich HHK, and then, silver nanoparticles (AgNPs) were in situ anchored in the sulfur-containing amino acid residues of HHK. After the ultrasonic degradation test, HHK/PEO/PVA nanofibrous mats treated with 0.005-M silver nitrate were selected due to their relatively complete structures. It was observed by TEM-EDS that the sulfur-containing amino acids in HHK were the main anchor points of AgNPs. The results of FTIR, XRD and the thermal analysis suggested that the hydrogen bonds between PEO and PVA were broken by HHK and, further, by AgNPs. AgNPs could act as a catalyst to promote the thermal degradation reaction of PVA, PEO and HHK, which was beneficial for silver recycling and medical waste treatment. The antibacterial properties of AgNP-HHK/PEO/PVA nanofibers were examined by the disk diffusion method, and it was observed that they had potential antibacterial capability against Gram-positive bacteria, Gram-negative bacteria and fungi. In addition, HHK in the nanofibrous mats significantly improved the cell proliferation of NIH3T3 cells. These results illustrated that the AgNP-HHK/PEO/PVA nanofibrous mats exhibited excellent antibacterial activity and the ability to promote the proliferation of fibroblasts, reaching our target applications.     

Controlled magnetic nanofiber hydrogels by clustering ferritin

We have fabricated biocompatible nanofiber hydrogels with diverse sizes of ferritin clusters according to the mixing temperature of solutions employing electrospinning. Poly(vinyl alcohol) (PVA) was used as a polymeric matrix for fabricating nanocomposites. By thermal means we controlled the interaction between the host PVA hydrogel and the protein shell on ferritin bionanoparticles to vary the size and concentration of ferritin clusters. The clustering of ferritin was based on the partial unfolding of a protein shell of ferritin. By studying the magnetic properties of the PVA/ferritin nanofibers according to the mixing temperature of the PVA/ferritin solutions, we confirmed that the clustering process of the ferritin was related to changes in the superparamagnetic properties and magnetic resonance imaging (MRI) contrast of the PVA/ferritin nanofibers. PVA/ferritin nanofiber hydrogels with diverse spatial distributions of ferritin nanoparticles are applicable as MRI-based noninvasive detectable cell culture scaffolds and as artificial muscles because of their improved superparamagnetic properties.     

聚丙烯酰胺/蒙脱土纳米复合物-聚乙烯醇共混膜的制备及其渗透汽化性能

用原位聚合法制备聚丙烯酰胺/蒙脱土(PAM/MMT)纳米复合材料, 通过透射电镜研究了蒙脱土在聚丙烯酰胺基体中的形貌和分布. 结果表明, 蒙脱土以片层结构分布在聚合物基体中. 用超声波分散聚乙烯醇和聚丙烯酰胺-蒙脱土共混铸膜液制得共混膜, 用红外吸收光谱和扫描电镜研究了两者的相互作用和形貌. 考察了共混膜在异丙醇-水混合溶液中的溶胀吸附性能及共混比和蒙脱土含量对膜分离性能的影响, 结果显示, 聚乙烯醇膜中添加适量的蒙脱土纳米粒子可以大大改善膜的分离选择性.     

Novel TEMPO-oxidized cellulose nanofiber/polyvinyl alcohol/polyethyleneimine nanoparticles for Cu2+ removal in water

Cellulose - In this study, environmentally friendly TEMPO-oxidized cellulose nanofiber (TO-CNF)/polyvinyl alcohol (PVA)/polyethyleneimine (PEI) nanoparticles were obtained by assembling PEI into...     

Propolis-Based Nanofiber Patches to Repair Corneal Microbial Keratitis

In this research, polyvinyl-alcohol (PVA)/gelatin (GEL)/propolis (Ps) biocompatible nanofiber patches were fabricated via electrospinning technique. The controlled release of Propolis, surface wettability behaviors, antimicrobial activities against the S. aureus and P. aeruginosa, and biocompatibility properties with the mesenchymal stem cells (MSCs) were investigated in detail. By adding 0.5, 1, and 3 wt.% GEL into the 13 wt.% PVA, the morphological and mechanical results suggested that 13 wt.% PVA/0.5 wt.% GEL patch can be an ideal matrix for 3 and 5 wt.% propolis addition. Morphological results revealed that the diameters of the electrospun nanofiber patches were increased with GEL (from 290 nm to 400 nm) and Ps addition and crosslinking process cause the formation of thicker nanofibers. The tensile strength and elongation at break enhancement were also determined for 13 wt.% PVA/0.5 wt.% GEL/3 wt.% Ps patch. Propolis was released quickly in the first hour and arrived at a plateau. Cell culture and contact angle results confirmed that the 3 wt.% addition of propolis reinforced mesenchymal stem cell proliferation and wettability properties of the patches. The antimicrobial activity demonstrated that propolis loaded patches had antibacterial activity against the S. aureus, but for P. aeruginosa, more studies should be performed.