Polystyrene Microfibers Research Articles

CARACTERIZAÇÃO MORFOLÓGICA DE MICROFIBRAS ELETROFIADAS DE POLIESTIRENO

Since wastewater treatment is of great interest to society, it is important to develop techniques that perform this treatment by removing pollutants such as dyes, pesticides, and metals. In this context, adsorption stands out as a promising method in the treatment of effluents, allied to this, as polymeric membranes considerably improve the ability to remove pollutants. Carbon-based additives, such as graphene oxide, have been used in the area of adsorption because they are an adsorbent capable of removing metallic ions and dyes. Thus, it is interesting to carry out studies of the polystyrene polymer with graphene oxide, aiming at the production of adsorbent membranes. To this end, the production of polystyrene was first analyzed, with graphene oxide added to the polymer matrix in the future. Thus, polystyrene microfibers were produced using the electrospinning technique and analyzed morphologically using optical microscopy and scanning electron microscopy (SEM). With the help of ImageJ and OriginPro 8.5 software, a histogram of the frequency distribution of microfiber diameters and the normal curve was created. Through the results obtained, it was observed that there was the production of microfibers with considerable morphology, as fibers with beads and agglomerates were not observed.. From the histogram, it was noted that the microfibers had an average diameter of 5.73 µm.

Integrated FRET Polymers Spatially Reveal Micro- to Nanostructure and Irregularities in Electrospun Microfibers.

A spatial view of macroscopic polymer material properties, in terms of nanostructure and irregularities, can help to better understand engineering processes such as when materials may fail. However, bridging the gap between the molecular-scale arrangement of polymer chains and the spatially resolved macroscopic properties of a material poses numerous difficulties. Herein, an integrated messenger material that can report on the material micro- to nanostructure and its processes is introduced. It is based on polymer chains labeled with fluorescent dyes that feature Förster resonance energy transfer (FRET) dependent on chain conformation and concentration within a host polymer material. These FRET materials are integrated within electrospun polystyrene microfibers, and the FRET is analyzed by confocal laser scanning microscopy (CLSM). Importantly, the use of CLSM allows a spatial view of material nanostructure and irregularities within the microfibers, where changes in FRET are significant when differences in fiber geometries and regularities exist. Furthermore, changes in FRET observed in damaged regions of the fibers indicate changes in polymer conformation and/or concentration as the material changes during compression. The system promises high utility for applications where nano-to-macro communication is needed for a better understanding of material processes.

Pelletizing highly porous covalent triazine framework under mild conditions and applying it as adsorbent for Ru3+ ions

CTFs (Covalent triazine frameworks) exhibit exceptional porosity and the ability to incorporate hetero-atoms (e.g. Ru) into their microstructures makes them versatile for several applications. However, pelletized form of the catalysts is required for various industrial processes. Although there are several methods available for pelletizing catalysts, but porosity of the pelletized CTF particles is compromised by applying these processes. In this study, CTF was synthesized by polymerizing Terephthalonitrile (TN) and pelletizing it by using Polystyrene (PS) and PVP. In CTF-PS composites, CTF particles were interconnected by PS microfibers with thickness ranging from 3 to 230 μm, while PVP and CTF were bonded by weak Van der Waals bonding. BET analysis showed Type-I isotherms for CTF-PS, and CTF-PVP composites, indicating that the materials were typically microporous, with an average pore size of ∼2 nm. Surface area values for the CTF-PVP, and CTF-PS were measured as 1128.7, and 610.81 m2g-1, meanwhile, pore volumes for the same were recorded as 0.532, and 0.291 cm3g-1, respectively. Owing to the small amount (10 %) of PVP in its composites CTF-PVP pellets retained most of the pores, maintaining almost 80 % of the porosity but could not remain intact in protic solvents. However, the CTF-PS pellet demonstrated excellent stability in protic solvents, making it suitable for support for the Ru catalyst or Ru extraction from solution. At 60 °C, by using 500 μM solution of RuCl3.3H2O 26 % of Ru was attached to the CTF-PS pellet, which can be an excellent prospect for lab scale catalytic reaction or industrial application.

Electrospinning Preparation, Structure, and Properties of Fe3O4/Tb(acac)3phen/Polystyrene Bifunctional Microfibers.

Compared to single functional materials, multifunctional materials with magnetism and luminescence are more attractive and promising; Thus, it has become an important subject. In our work, bifunctional Fe3O4/Tb(acac)3phen/polystyrene) microfibers with magnetic and luminescent properties (acac: acetylacetone, phen: 1,10-phenanthroline) were synthesized by simple electrospinning process. The doping of Fe3O4 and Tb(acac)3phen made the fiber diameter larger. The surface of pure polystyrene microfibers and microfibers doped only with Fe3O4 nanoparticles were chapped similar to bark, whereas the surface of the microfibers was smoother after doping with Tb(acac)3phen complexes. The luminescent properties of the composite microfibers were systematically studied in contrast to pure Tb(acac)3phen complexes, including excitation and emission spectra, fluorescence dynamics, and the temperature dependence of intensity. Compared with the pure complexes, the thermal activation energy and thermal stability of composite microfiber was significantly improved, and the luminescence of the unit mass of Tb(acac)3phen complexes in composite microfibers was stronger than that in pure Tb(acac)3phen complexes. The magnetic properties of the composite microfibers were also investigated using hysteresis loops, and an interesting experimental phenomenon was found that the saturation magnetization of the composite microfibers gradually increased with the increase in the doping proportion of terbium complexes.

Simple fabrication of an electrospun polystyrene microfiber filter that meets N95 filtering facepiece respirator filtration and breathability standards.

During the global spread of COVID-19, high demand and limited availability of melt-blown filtration material led to a manufacturing backlog of N95 Filtering Facepiece Respirators (FFRs). This shortfall prompted the search for alternative filter materials that could be quickly mass produced while meeting N95 FFR filtration and breathability performance standards. Here, an unsupported, nonwoven layer of uncharged polystyrene (PS) microfibers was produced via electrospinning that achieves N95 performance standards based on physical parameters (e.g., filter thickness) alone. PS microfibers 3-6μm in diameter and deposited in an ~5 mm thick filter layer are favorable for use in FFRs, achieving high filtration efficiencies (≥97.5%) and low pressure drops (≤15 mm H2O). The PS microfiber filter demonstrates durability upon disinfection with hydroxyl radicals (•OH), maintaining high filtration efficiencies and low pressure drops over six rounds of disinfection. Additionally, the PS microfibers exhibit antibacterial activity (1-log removal of E. coli) and can be modified readily through integration of silver nanoparticles (AgNPs) during electrospinning to enhance their activity (≥3-log removal at 25 wt% AgNP integration). Because of their tunable performance, potential reusability with disinfection, and antimicrobial properties, these electrospun PS microfibers may represent a suitable, alternative filter material for use in N95 FFRs.

Inkjet Printing of Electrodes on Electrospun Micro- and Nanofiber Hydrophobic Membranes for Flexible and Smart Textile Applications.

With the increasing demand for smart textile and sensor applications, the interest in printed electronics is rising. In this study, we explore the applicability of electrospun membranes, characterized by high porosity and hydrophobicity, as potential substrates for printed electronics. The two most common inks, silver and carbon, were used in inkjet printing to create a conductive paths on electrospun membranes. As substrates, we selected hydrophobic polymers, such as polyimide (PI), low- and high-molecular-weight poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (PVB) and polystyrene (PS). Electrospinning of PI and PVB resulted in nanofibers in the range of 300-500 nm and PVB and PS microfibers (1-5 μm). The printed patterns were investigated with a scanning electron microscope (SEM) and resistance measurements. To verify the biocompatibility of printed electrodes on the membranes, an indirect cytotoxicity test with cells (MG-63) was performed. In this research, we demonstrated good printability of silver and carbon inks on flexible PI, PVB and PS electrospun membranes, leading to electrodes with excellent conductivity. The cytotoxicity study indicated the possibility of using manufactured printed electronics for various sensors and also as topical wearable devices.

The modification of optical behavior of polystyrene microfibers by the incorporation of Gd doped ZnO nanoparticles

The paper reports the synthesis of Zinc Oxide (ZnO) nano particles in pure and Gadolinium (Gd) doped forms via hydrothermal method. The annealing temperatures for the samples were fixed at 600 °C and 800 °C. The ZnO nano particles in their pure and Gd doped forms were incorporated in the Polystyrene matrix and drawn to microfibers by the method of electrospinning (ES). The structural studies were carried out using Scanning Electron Microscopy-Energy Dispersive x-ray Spectroscopy (SEM-EDS), Transmission Electron Microscopy (TEM), x-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The optical absorption and emission properties were studied using UV-Visible Absorption spectroscopy and Fluorescence Spectroscopy. The SEM-EDS confirmed the presence of Gd in ZnO. In the ZnO structures more crystallinity was observed for samples annealed at 800 °C. The particle size of the prepared nano particles were found to vary from 77 nm to 194 nm. The optical absorption behavior of the samples was explained using Brus effective mass model. The fluorescence emission spectrum of the nano particle samples were analyzed and found that the emission properties depend on their particle size. The XRD, UV-Visible and Fluorescence analysis of fibers confirmed the presence of ZnO and Gd doped ZnO nano particles in the polystyrene fibers. The distinct optical absorption and emission behavior of the microfibers were greatly affected due to the presence of nano particles in the polymer matrix.

Improvised centrifugal spinning for the production of polystyrene microfibers from waste expanded polystyrene foam and its potential application for oil adsorption

A straightforward approach to recycle waste expanded polystyrene (EPS) foam to produce polystyrene (PS) microfibers using the improvised centrifugal spinning technique is demonstrated in this work. A typical benchtop centrifuge was improvised and used as a centrifugal spinning device. The obtained PS microfibers were characterized for their potential application for oil adsorption. Fourier transform infrared spectroscopy results revealed similarity on the transmission bands of EPS foam and PS microfibers suggesting the preservation of the EPS foam’s chemical composition after the centrifugal spinning process. Scanning electron microscopy displayed well-defined fibers with an average diameter of 3.14 ± 0.59 μm. At the same time, energy dispersive X-ray spectroscopy revealed the presence of carbon and oxygen as the primary components of the fibers. Contact angle (θCA) measurements showed the more enhanced hydrophobicity of the PS microfiber (θCA = 100.2 ± 1.3°) compared to the untreated EPS foam (θCA = 92.9 ± 3.5°). The PS microfiber also displayed better oleophilicity compared to EPS foam. Finally, the fabricated PS microfibers demonstrated promising potential for oil removal in water with a calculated sorption capacity value of about 15.5 g/g even at a very short contact time. The fabricated PS fiber from the waste EPS foam may provide valuable insights into the valorization of polymeric waste materials for environmental and other related applications.

Coloration of electrospun polystyrene (PS) microfibers by the continuous dyeing method

Herein the research on coloration of polystyrene (PS) microfibers with disperse dyes by the pad-dry-cure method has been reported. The PS microfibers were fabricated via electrospinning technique and pretreated with a wetting agent (Hostapal MRN) for 5 min prior to padding in dye liquor for over-coming hydrophobicity and improving dye up-take. The microfiber samples were dipped and nipped twice in the dye solutions and between the padding-mangles, respectively. The curing temperature and curing time were optimized to be 80 °C and 90 s, respectively. The influence of effect of dye concentrations on K/S values was also studied. Highest K/S values were obtained at 3% dye concentrations. The optimized samples demonstrated good to very good color bleeding resistance in color fastness to washing, light and hot-pressing. The scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) did not show any significant effect of the dyeing process on morphology and chemical structures of the PS microfibers.

Activated carbon-doped polystyrene fibers for direct contact membrane desalination

Membranes for direct contact membrane distillation were produced from electrospun polystyrene microfibers doped with activated carbon. The addition of activated carbon reduced the hydrophobicity of the fibers. Therefore, desalination membranes were fabricated in a multi-layer construction with undoped polystyrene as the outer layers and activated carbon-doped polystyrene as an inner layer. Membranes including activated carbon-doped layers showed a 20× greater specific surface area as compared to undoped membranes. The vapor flux of the membranes containing layers doped with activated carbon (6.3 ± 0.7 kg/m2/h) was not statistically different from that with an all polystyrene construction (8.1 ± 1.2 kg/m2/h). The membranes retained their desalination capabilities despite the addition of the activated carbon.

Hierarchical Composite Meshes of Electrospun PS Microfibers with PA6 Nanofibers for Regenerative Medicine.

One of the most frequently applied polymers in regenerative medicine is polystyrene (PS), which is commonly used as a flat surface and requires surface modifications for cell culture study. Here, hierarchical composite meshes were fabricated via electrospinning PS with nylon 6 (PA6) to obtain enhanced cell proliferation, development, and integration with nondegradable polymer fibers. The biomimetic approach of designed meshes was verified with a scanning electron microscope (SEM) and MTS assay up to 7 days of cell culture. In particular, adding PA6 nanofibers changes the fibroblast attachment to meshes and their development, which can be observed by cell flattening, filopodia formation, and spreading. The proposed single-step manufacturing of meshes controlled the surface properties and roughness of produced composites, allowing governing cell behavior. Within this study, we show the alternative engineering of nondegradable meshes without post-treatment steps, which can be used in various applications in regenerative medicine.

Effects of surface morphology of electrospun polystyrene fiber on its air filtration performance

A series of membranes, made from polystyrene microfibers and with different morphologies, were fabricated via electrospinning method in this study. In addition, not only porous fibers but also beaded fibers were obtained by adjusting the experimental temperature in a reasonable and appropriate way. Assisted by a high-speed camera, the images of jet behaviors at different experimental temperatures were captured for the purpose of in-depth and comprehensive understanding of formation mechanism of different fiber morphologies. Mono-disperse sodium chloride aerosol particles with different sizes and cigarette smoke were used, for the attainment of the objective of evaluation on the filtration performance of fabricated membranes. The experimental results showed that straight fiber with narrow pores on its surface can be obtained at 20°C spinning temperature because of the rapid jet motion and solvent evaporation, and also, beaded fibers can be fabricated in the situation of spinning temperature higher than 25°C due to the sudden change of surface tension resulted from the fast solvent evaporation. The porous straight fibers exhibited excellent filtration performance to cigarette smoke and aerosol containing particles of all sizes (99.76%, 99.92%, and 99.99% filtration efficiency for particles with sizes of 0.3 µm, 0.5 µm, and 1 µm, respectively).

In situ synthesized hydro-lipophilic nano and micro fibrous bacterial cellulose: polystyrene composites for tissue scaffolds

3D networks of fibrous materials are preferred for cell growth and proliferation as they mimic the extracellular matrix. Moreover, materials with the multi-dimensional fibers, that is, a combination of nano- and microfibers, are preferred as they would benefit from the high surface area offered by nanofibers and structural integrity imparted by the microfibers. This paper presents a unique and facile way of making such fiber-on-fiber composites from bacterial cellulose nanofibers and polystyrene (PS) microfibers. These composites are unique as the PS microfibers are lipophilic, while the cellulose nanofibers are hydrophilic. This not only enables cell attachment but also ensures nutrition supply. Two types of composites were obtained in this work—interpenetrated and layered—by in situ growth of bacterial cellulose into compressed and uncompressed nonwoven PS fabrics, respectively. The layered composite showed two times the cell growth exhibited by the control, while the interpenetrated composite offered a fourfold cell growth, after 24 h. Later (at 48 h), the interpenetrated composites show a decline in cell growth, while the layered composite showed an increase. The role of hydrophilic cellulose fibers in nutrition supply, lipophilic PS in cell attachment, optimal pore size in cell trapping and surface area in enhanced growth is discussed, in addition to the role of the composite morphology (layered or interpenetrated) in cell growth.

Enhancement of the Spontaneous Emission Rate of Perovskite Nanowires Coupled into Cylindrical Hollow Nanocavities Formed on the Surface of Polystyrene Microfibers

Fluorescent CsPbBr3 nanowires are uniformly integrated into a porous polystyrene matrix in the form of microfibers to investigate the changes in their spontaneous emission rate. Cylindrical hollow ...

Self-propulsion of bent bimetallic Janus rods

In this paper, the sideways self-propulsion behaviour of straight and bent Janus micro-rods is presented. Janus micro-rods are prepared by consecutively sputter-coating platinum and gold on different sides of aligned polystyrene micro-fibers produced via electrospinning. Self-propulsion is induced via the reaction of hydrogen peroxide at the Janus particle interface, and the effect of the particles shape on their self-propulsion trajectories is studied. We show that the self-propulsion trajectories change from straight to circular when the particle shape is changed from a straight to an ‘L’ shaped rod. In order to understand and quantitatively describe the particle shape effects, we adopted a mathematical model developed by Hagen et al (2011 J. Phys.: Condens. Matter. 23 194119) to predict their trajectories. We show that the trajectory of irregularly shaped micro-rods depends only on the particle shape. The predicted trajectories for various particle shapes are in good agreement with the experimental observations.

Nanocellular foams confined within PS microfibers obtained by CO2 batch foaming process

Nanocellular foams localized in PS (polystyrene) microfibers with 10.0---20.0 µm-diameter were prepared by CO2 (carbon dioxide) one-step foaming method. The CO2-soaking conditions were operated at the slightly above Tg (glass transition temperature) of PS that maintains the fiber structures was investigated. The control of bubble nucleation in the foaming mechanism was driven by the depressurization rate adjustment. The higher depressurization rate and the use of the lower diameter of PS microfibers have resulted in the reduction of the obtained cell diameter and larger of cell density. The average of the smallest cell size diameter of 60---70 nm with the number of cell density of 1.1 × 1014 cmź3 was obtained by the depressurization rate of 3.0 MPa/min using PS microfibers of 10 µm-diameter. The ratio of foamed region (core region) and the fiber radius was slightly increased by the reduction of the depressurization rate and using the larger diameter of PS microfibers. The formation of cellular structures could be clarified by P---T (pressure---temperature) profiles combined phase diagram of CO2---PS system. The changed in thermal properties and mechanical properties of the PS fibers caused by the formation of the nanocellular foams were reported in this study.

Cell Adhesion Induced Using Surface Modification with Cell-Penetrating Peptide-Conjugated Poly(ethylene glycol)-Lipid: A New Cell Glue for 3D Cell-Based Structures.

We synthesized a novel material, cell-penetrating peptide-conjugated poly(ethylene glycol)-lipid (CPP-PEG-lipid), that can induce the adhesion of floating cells. Firm cell adhesion with spreading could be induced by cell surface modification with the CPP-PEG-lipids. Cell adhesion was induced by CPPs but not by any other cationic short peptides we tested. Here, we demonstrated adherence using the floating cell line CCRF-CEM as well as primary human T cells, B cells, erythrocytes, and hepatocytes. As compared to cells grown in suspension, adherent cells were more rapidly induced to attach to substrates with the cell-surface modification. The critical factor for attachment was localization of CPPs at the cell membrane by PEG-lipids with PEG > 20 kDa. These cationic CPPs on PEG chains were able to interact with substrate surfaces such as polystyrene (PS) surfaces, glass surfaces, and PS microfibers that are negatively charged, inducing firm cell adhesion and cell spreading. Also, as opposed to normal cationic peptides that interact strongly with cell membranes, CPPs were less interactive with the cell surfaces because of their cell-penetrating property, making them more available for adhering cells to the substrate surface. No effects on cell viability or cell proliferation were observed after the induction of cell adhesion. With this technique, cells could be easily immobilized onto PS microfibers, an important step in fabricating 3D cell-based structures. Cells immobilized onto 3D PS microfibers were alive, and human hepatocytes showed normal production of urea and albumin on the microfibers. This method is novel in inducing firm cell adhesion via a one-step treatment.

Biaxial reinforcements for polybutene-1 medical-tubes achieved via flow-design controlled morphological development of incorporated polystyrene: In-situ microfibrillation, alignment manipulation and performance optimization

Abstract By means of goal-directed flow designing and morphology controlling, this paper opened up an efficient method of continuously mass-producing biaxially reinforced polystyrene (PS)/polybutene-1(PB-1) tubes for medical application. The experimental results showed that the PS microfibers were in-situ formed by imposing a specific convergent flow onto the off-die PS/PB-1 blend melt, exhibiting excellent dispersion, high aspect ratio and good interfacial contact. As a result, the ultimate axial strength (UAS) of the microfibrillar PS/PB-1 tubes was enhanced from 29.9 MPa of conventional neat PB-1 tubes to 41.3 MPa. Moreover, by introducing the rotating mandrel or die to modify the flow to helical convergent flow, the formed PS microfiber deviated from axial direction to further improve hoop damage strength (HDS) performances. Particularly, via counter-helical convergent flow extrusion controlled by the counter-rotating mandrel and die system, the opposite-handed helical configuration of PS microfibers was brought out to eliminate the inter-fiber relative slip. As a result, the PS/PB-1 composite tubes exhibited remarkably reinforced mechanical performances in both UAS (40.3PMa) and HDS (34.9 MPa) tests, improved by 34.8% and 48.5% compared to Conv-E neat PB-1. These results suggest that such bi-axially reinforced microfibrillar tubes could be of benefit to ensure the structural integrity of artificial medical tubing systems.

In-situ microfibrillation of polystyrene(PS)/polybutene-1 (PB-1) composites prepared via melt drawing:morphological evolution and properties

In-situ Polystyrene (PS)/Polybutene-1 (PB-1) microfibrillar composites were prepared by applying “melt drawing” technique. The phase morphology, crystal structure, and mechanical performances of the produced sheets were investigated. The mechanical tests showed distinct rise of samples’ strength and modules with the increasing of melt drawing ratio (MDR). And, the discernible differences in mechanical performances between the PS added and neat PB-1 systems were also detected. The 2D-WAXD results proved that by increasing the melt drawing ratio (MDR), the orientation degree of PB-1 and PS/PB-1 composites increased gradually indicating the formation of highly oriented PB-1 crystals. Interestingly, as a respond to the external drawing field, the morphologies of PS phase dispersed in the PB-1 matrix were transformed from isotropic spherical droplets to anisotropic microfibers at high aspect ratio during the melt-drawing process. Different from the widely reported mechanism for cool-drawing microfibrillation, in this study, PS phase firstly assembled together due to its fine fluidity, and then deformed to form microfiber structure as observed in SEM pictures. Accordingly, new mechanism for in-situ microfibrillation of PS/PB-1 composites during melt drawing was proposed as: “coalescing”, “deforming”, “needle-like tails growing and propagating” and “microfibrillating”. As a result, the as-prepared microfibrillar composites at high value of MDR (4.89) exhibited superior mechanical performances (120.2 MPa in tensile strength) than that of as-prepared neat PB-1 samples (91.4 MPa). The reinforcing effect of PS microfibers on the PS/PB-1 composites was also confirmed through annealing experiments. This study illustrate the morphological evolution mechanism and morphology-property relationship in PS/PB-1 systems and indicate a technique to transform “defects” into “reinforcements”.

The self-assembled Ru(bpy)3(PF6)2 nanoparticle on polystyrene microfibers and its application for ECL sensing

Ruthenium nanoparticle tris(2,2'-bipyridyl)ruthenium(II) bis(hexafluorophosphate) (Ru(bpy)3(PF6)2, RuNP) was self-assembled on polystyrene (PS) electrospun microfibers. The formation of RuNP is attributed to the sulfonated PS (SPS) microfibers' high adsorptive capability of 94% for Ru(bpy)3(2+), as well as the strong interaction between the Ru(bpy)3(2+) and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6). The RuNP/SPS microfibers exhibited an enhanced electrochemiluminescence (ECL) emission, 2.3 times higher than that from Ru(bpy)3(2+)/SPS microfibers and 6.6 times higher than that from Ru(bpy)3(2+)/SPS continuous thin films. It is worthy of note that, as a result of the hydrophobic nature of the RuNP, the transfer of water-insoluble α-naphthol is accelerated, and thus the α-naphthol ECL quenching efficiency is enhanced. An ECL sensor based on the RuNP/SPS microfibers was fabricated and used to detect low concentrations of α-naphthol. The detection limit was of 1.0 nM (S/N > 3), and the linear response ranged from 0 to 18 μM. This sensor has been successfully applied to measure the α-naphthol content in pesticide carbaryl samples. Our work provides a very simple and cost-effective method to fabricate RuNP on polymer microfibers with great potential in the field of chemo/biosensors.