Polystyrene Solutions Research Articles

Polymer Concentration Effect on Nanofiber Growth Using Pulsed Electrospinning

In this paper, a new electrospinning device is designed and fabricated based on the pulsed system. The general model of electrospinning process is represented. Moreover, the produced nanofibers are characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR). The effects of concentration and voltage depended on the collector rotation are investigated on the electrospinning process. The three different polystyrene solutions with the three various voltages are used to produce several polymer nanofibers. The experimental results reveal that the increase in polymer concentration enlarges the thickness of nanofiber while increase in applied voltage causes to decrease the nanofiber thickness. The results are compared with similar research. For our research, we applied the 10 KV voltage instead of 20 KV voltage as indicated in the literature. The measured results show that the proposed model has good adjacency with respect to analytical and experimental data.

Self-organized nanocrystal rings formed by microemulsion for selective recognition of proteins and immunoassays.

A simple and cheap method to fabricate a nanocrystal ring pattern was developed by utilization of a microemulsion in this study. The mixture of polystyrene and stabilizer dichloromethane solution that contained nanocrystal aqueous solution, prepared through shaking, was applied to fabricate a reverse microemulsion. After spreading and evaporating the solvent of microemulsion on a glass slide, an ordered honeycomb film was produced, accompanied by the formation of a nanocrystal ring pattern. The nanocrystal pattern could be readily applied for immunoassays and recognition of proteins. The pattern with antibody marked by a green colored nanocrystal specifically bound with antigen labeled by a red colored nanocrystal, leading to the enhancement in red fluorescent ring pattern and decrease in green fluorescent pattern. When the unlabeled antigen was added, the green fluorescent pattern was recovered. In addition, the ring pattern with immunocomplex could selectively recognize antigen and transferrin proteins. This strategy reveals that these patterns have potential applications in biochips, biosensors, imaging analysis and so forth.

SYNTHESIS AND CHARACTERIZATION OF PLATINUM NANOCOMPOSITES

This work related to fabrication of platinum nano particles, reveals considerably outstanding catalytic and electrical properties and preparation of Pt- PS nano composite. For this study Pt nano particles were synthesized by wet chemical method. Pt particles with 0.25%, 0.5%, 1% and 2% concentration amounts were added into the polystyrene solution, acquired by recycled PS. Three different composites which possess a distinct percentage of platinum were produced. Fibers were fabricated by electro spinning method afterward. Pt particles which were produced by wet chemical method and fibers were analyzed by SEM-EDS. There were various test and measurement methods performed to determine the characteristics of the platinum nano composite.

Polystyrene bioactive nanofibers using orange oil as an ecofriendly solvent

ABSTRACTSolution blow spun polystyrene (PS) nanofibers were produced from 20 to 30 wt % PS solutions using toluene (industrial solvent) and orange oil (green solvent). The latter being composed of d‐limonene (97.06%) as determined by gas chromatography–mass spectroscopy. The rheological behavior and volatility of the solvents and polymer solutions were correlated with fiber morphology, accessed by scanning electron microscopy. Thermal analysis was used to determine the thermal behavior of fibers. The antimicrobial activity of orange oil was tested for potential applications of the spun mats in active food packaging. Results showed that the nanofibers spun from orange oil solutions had average diameters of 306 ± 74 nm as opposed to 441 ± 110 nm for toluene. Moreover, when compared with fiber spun from toluene solutions, orange oil yielded more flexible fibers with slightly lower contact angles and better antimicrobial properties due to the presence of residual oil confirmed by Fourier‐transform infrared spectroscopy. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47337.

Dispersion state of carbon black in polystyrene produced with different dispersion media and its effects on composite rheological properties

The dispersion state and aggregate structure of carbon black in polystyrene composites prepared by solvent casting suspensions in different dispersion media, i.e., chloroform, tetrahydrofuran, and toluene, with different particle contents and their effects on the bulk rheological properties of the composites were investigated by transmission electron microscopy, ultrasmall-angle and small-angle X-ray scattering, and dynamic viscoelasticity measurements. The macroscopic dispersion state of carbon black in the solvent-cast films was largely affected by the dispersion medium, reflecting the stability of the suspension in the polystyrene solution. The mass fractal dimension of carbon black in the polymeric matrix, which was evaluated by X-ray scattering techniques with a resolution of nanometers, tended to exhibit a higher value for the dispersion media with less carbon black dispersibility. The surface fractal dimension of carbon black in the polymer was independent of the dispersion medium and exhibited a lower value than carbon black powder due to physical adsorption of the polymer on the particle surface. The viscoelastic moduli for the melt polymer composites below and above the percolation limit varied according to the dispersion media, reflecting the difference in the macroscopic dispersion state and aggregate structure of carbon black in polystyrene. The dispersion state and aggregate structure of carbon black in polystyrene composites prepared by solvent casting suspensions in different dispersion media with different particle contents and their effects on the bulk rheological properties of the composites were investigated by transmission electron microscopy, ultrasmall-angle and small-angle X-ray scattering, and dynamic viscoelasticity measurements. The viscoelastic moduli of the melt polymer composites below and above the percolation limit varied with the dispersion medium, reflecting the difference in the macroscopic dispersion state and aggregate structure of carbon black in polystyrene.

Porosity control of nanoporous CuO by polymer confinement effect

We propose a simple method for fabricating porous CuO, which is elementally abundant, nontoxic, environmentally stable, and a good electrochemical performing material, and easily controlling pore size by using a mixture of Cu precursor and polystyrene solutions followed by heat treatment, which we named polymer-confined direct solution pyrolysis (PDSP). We mixed an ionized metal solution and polymer template with different molecular weights, and then burned out the polymer template in air. The fabrication technique and application of nanoporous CuO produced by PDSP are presented herein. The applications studied were metal oxides for nanoenergetic materials and a non-enzyme glucose sensor.

Pore‐Selective SnS Functionalization in Honeycomb‐Patterned Films by a Breath Figure Process Accompanied by Chemical Reaction

AbstractA new fabrication process for the pore‐selective functionalization of honeycomb‐patterned porous (HCP) films is demonstrated by a modified breath figure method accompanied by an in situ chemical reaction. A polymer solution containing one reactant is cast under humid conditions containing counter reactant to facilitate a chemical reaction at condensed droplet/polymer solution interface, which results in the pore‐selective functionalization of HCP films. Polystyrene (PS) solution containing tin(II) chloride is cast under humid conditions containing aqueous hydrogen sulfide for the formation of tin sulfide (SnS)‐functionalized PS HCP films. H2S humidity is generated by pumping ambient air through the aqueous sodium sulfide solution. Scanning electron microscopy, transmission electron microscopy, and elemental mapping analyses indicate the formation of SnS as thin layers selectively in the pores of PS HCP films.

Sorption of Methylene Blue on Polystyrene/Bentonite Film Composites

The method of mechanochemical dispersion of bentonite in a polystyrene solution was used to modify the polymer and obtain film materials with improved sorption characteristics with respect to the methylene blue (MB) thiazine dye. It is found that the kinetics of the dye sorption are described by the pseudo-first-order equation. The sorption equilibrium is described by the Langmuir isotherm. The values of the limiting sorption capacity and specific surface area of the composite are determined. It is shown that the sorption efficiency of the dye on the PS/bentonite composite increases tenfold as compared with the non-modified sorbent; the extraction rate increases from 10 to 90%. The method of IR spectroscopy is used to show that MB sorption on polystyrene and the PS/bentonite composite is accompanied by electrostatic and donor–acceptor interactions of the reaction sites of MB with the hydroxyl–containing groups of the composite.

The peculiar elongational viscosity of concentrated solutions of monodisperse PMMA in oligomeric MMA

Concentrated solutions of nearly monodisperse poly(methyl methacrylate), PMMA-270k and PMMA-86k, in oligo(methyl methacrylate), MMA o-4k and MMA o-2k, investigated by Wingstrand et al. (Phys Rev Lett 115:078302, 2015) and Wingstrand (2015) do not follow the linear-viscoelastic scaling relations of monodisperse polystyrenes (PS) dissolved in oligomeric styrene (Wagner in Rheol Acta 53:765–777, 2014a, in Non-Newtonian Fluid Mech 222:121–131, 2014b; Wagner et al. in J Rheol 59:1113–1130, 2015). Rather, PMMA-270k shows an attractive interaction with MMA, in contrast to the interaction of PMMA-86k and MMA. This different behavior can be traced back to different tacticities of the two polymers. The attractive interaction of PMMA-270k with o-4k creates pseudo entanglements, which increase the interchain tube pressure, and therefore, the solution PMMA-270k/o-4k shows, as reported by Wingstrand et al. (Phys Rev Lett 115:078302, 2015), qualitatively a similar scaling of the elongational viscosity with $$ {\left(\dot{\varepsilon}{\tau}_R\right)}^{-1/2} $$ as observed for polystyrene melts. For the solution PMMA-270/o-2k, this effect is only seen at the highest elongation rates investigated. The elongational viscosity of PMMA-86k dissolved in oligomeric MMA is determined by the Rouse time of the melt, as in the case of polystyrene solutions.

Formation of Monolayer Polystyrene Array Template for Gold Nanomesh Structure

In this study, the preparation of monolayer array template was performed using 0.2 µm polystyrene (PS) nanospheres monodisperse micro particle deposited onto Indium Tin Oxide (ITO) coated glass substrate. The template was used to arrange the gold (Au) in nanomesh structure thus, enhance its homogeneity for having better sensitivity and repeatability in the plasmonic sensor application. PS nanosphere template was prepared by diluting 0.2 µm PS liquid with ethanol in the ratio of 1:3 and stirred with 400 rpm for 1 hours at 40 °C. Next, the PS solution was spin coated on ITO substrate at different speed variation starting from 200 rpm to 800 rpm in 3 minutes at room temperature. The template structure was then inspected with Field Emission-Scanning Electron Microscopy (FESEM). It was found that, the PS nanosphere template with 600 rpm speed shows the most orderly arrangement of PS array. Subsequently, the PS array template was used as a mask to deposit gold (Au) and performed via direct current (DC) sputtering method. Finally, the Au nanomesh structure was obtained using the lift ‒ off process of PS nanosphere template.

Mechanical spectral hole burning of an entangled polymer solution in the stress-controlled domain.

Nonresonant spectral hole burning has proven to be a versatile method to characterize the dynamics of complex fluids, including polymers. Early work focused on dielectric susceptibility measurements in glass forming liquids, while recent work from our lab used mechanical viscoelastic measurements to investigate polymer melts and solutions. While the observed results were similar, the interpretations were different, with the former being interpreted by attributing the "holes" in the response as being due to dynamic heterogeneity in the system that is related to the glass or other transition, while the latter was interpreted in a way that suggested that the observed holes depend on the type of dynamics (Rouse, terminal, etc.) rather than an identifiable spatial heterogeneity. In this work, we have expanded mechanical spectral hole burning (MSHB) into the stress-controlled domain and carried out experiments in the rubbery regime of a polystyrene solution, similar to one which was tested previously with strain-controlled MSHB. The effects of pump stress amplitude, pump frequency, and waiting time were investigated. The mechanical holes in both directions (vertical and horizontal) were successfully burned, unlike the strain-controlled MSHB experiments on the same polystyrene solution, in which vertical holes were at best incomplete. The hole intensity exhibits a linear relationship with the amount of energy dissipated in the system during the large mechanical pump modification. The results suggest that the stress-controlled MSHB can be combined with strain-controlled MSHB to build a more complete framework to investigate the dynamics of polymeric materials and is consistent with the dynamic heterogeneity being related to the type of dynamics rather than to localized heating effects.

Shear thinning in dilute and semidilute solutions of polystyrene and DNA

The viscosity of dilute and semidilute unentangled DNA solutions, in steady simple shear flow, has been measured across a range of temperatures and concentrations. For polystyrene solutions, measurements of viscosity have been carried out in the semidilute unentangled regime, while results of prior experimental measurements in the dilute regime have been used for the purpose of data analysis, and for comparison with the behaviour of DNA solutions. Interpretation of the shear rate dependence of viscosity in terms of suitably defined non-dimensional variables, is shown to lead to master plots, independent of temperature and concentration, in each of the two concentration regimes. In the case of semidilute unentangled solutions, defining the Weissenberg number in terms of a concentration dependent large scale relaxation time is found not to lead to data collapse across different concentrations. On the other hand, the use of an alternative relaxation time, with the concentration dependence of a single correlation blob, suggests the existence of universal shear thinning behaviour at large shear rates.

Decomposition of Q0 from FT-rheology into elastic and viscous parts: Intrinsic-nonlinear master curves for polymer solutions

In the medium amplitude oscillatory shear (MAOS) test, intrinsic nonlinearity Q0(ω) derived from Fourier-transform (FT)-rheology is an important material function for investigating the nonlinear responses of complex fluids. However, Q0 consists of elastic and viscous components without phase information, such as complex modulus |G*| obtained from the small amplitude oscillatory shear (SAOS) test. In this study, we decomposed Q0 into Q 0 ′(ω) and Q 0 ″(ω), as done for storage modulus G′ and loss modulus G″ in the SAOS test. Furthermore, intrinsic-nonlinear tan δ (≡tan δ3,0), which provides third-harmonic phase information, was calculated by dividing Q 0 ″ by Q 0 ′. First, we defined mathematically elastic nonlinearity Q 0 ′ and viscous nonlinearity Q 0 ″, and then investigated the physical meanings of Q 0 ′ and Q 0 ″. Second, we applied the intrinsic parameters Q 0 ′ and Q 0 ″ to monodisperse polystyrene solutions. All intrinsic-nonlinear master curves of Q 0 ′(ω) and Q 0 ″(ω) for model solutions showed similar behavior in the terminal regime (at low frequencies). Unentangled polymer solutions had the same intrinsic-nonlinear master curves. However, although the intrinsic-nonlinear master curves of entangled polymer solutions superimposed well at low De (near the terminal regime), they deviated at high De due to different entanglement densities. Therefore, two characteristic times, MAOS relaxation time and inflection time (τN and τinf), were determined from intrinsic-nonlinear master curves by comparing with terminal relaxation time and Rouse time (τL and τR) obtained from linear master curves. The results showed that intrinsic nonlinearities from the MAOS test are sensitive to relaxation processes (terminal and Rouse) of polymer chains. Finally, master curves were compared with predictions by the molecular stress function (MSF) model and the Pom-Pom model. The single-mode predictions of these two models described behavior changes qualitatively. However, both failed to achieve quantitative predictions of Q 0 ′(ω) and Q 0 ″(ω). On the other hand, the multimode MSF model agreed well with experimental data from the terminal regime to the inflection time scale under the terminal relaxation mode assumption.

Effects of interfacial interactions and interpenetrating brushes on the electrospinning of cellulose nanocrystals-polystyrene fibers

This study investigated the electrospinning of polystyrene solutions using added unmodified and modified (with grafted nitrobenzene and trifluoromethyl benzene functionalities and polystyrene brushes) cellulose nanocrystals (CNCs). A strong correlation existed between the formation of beads on the fibers and the degree of dispersion of CNC particles in the electrospinning mixtures. Agglomerates of CNC particles always concentrated in the form of beads. The best dispersion in N,N dimethylformamide (DMF) mixtures was obtained using CNC-2 surfaces that were modified using trifluoromethyl benzene functional groups. Using CNC-2 also resulted in both uniform and bead-free electrospun fibers. Despite good dispersion in DMF, the use of grafted polystyrene (PS) chains with CNC-g resulted in beads above a 1.0% concentration level. This result is attributed to more favorable interactions between the CNC-g brushes during the DMF solvent evaporation stage of electrospinning. The electrospinning of CNC/PS nanocomposites at very low CNC concentrations (<1.0%) showed strong adhesion bonds at the polymer-CNC interfaces. Excellent mechanical properties were also produced by using interpenetrating networks of surface brushes.

The Fractal Dimensions of Carbon-Black-Filled Polymers and Elastomers. Part 1. Materials and Methods of Investigation, and Morphology

Methods for preparing specimens and for processing the results obtained are described. Carbon black of grades T1 and KhS-72, monodispersed polystyrene (molecular weight 200 kDa), polyethylene, polybutadiene rubber, polyisoprene rubber, styrene butadiene elastomer, and butyl rubber were investigated. Two methods were used to prepare filled specimens. In the first case (model systems), the filler and polymer were mixed via a 1–5% solution of polystyrene in toluene. The carbon black content in the suspensions was varied in the range 1–60 wt%. After mixing, the specimens were subjected to ultrasound treatment on a UZDM-2T disperser (44 kHz) for ~10 min. In the second case, sulphur vulcanisates were obtained by the standard procedure. The morphology was studied by transmission electron microscopy (EM-301 electron microscope, Japan) using thin films or etching in high-frequency oxygen discharge plasma on a vacuum reactor (Edwards, UK). A procedure for processing electron micrographs with the aim of obtaining information about local and global fractal dimensions of particle aggregates is described.

Measuring and assessing first and second normal stress differences of polymeric fluids with a modular cone-partitioned plate geometry

We propose a simple, robust method to measure both the first and second normal stress differences of polymers, hence obtaining the full set of viscometric material functions in nonlinear shear flow. The method is based on the use of a modular cone-partitioned plate (CPP) setup with two different diameters of the inner plate, mounted on a rotational strain-controlled rheometer. The use of CPP allows extending the measured range of shear rates without edge fracture problems. The main advantage of such a protocol is that it overcomes limitations of previous approaches based on CPP (moderate temperatures not exceeding 120 °C, multiple measurements of samples with different volume) and yields data over a wide temperature range by performing a two-step measurement on two different samples with the same volume. The method was tested with two entangled polystyrene solutions at elevated temperatures, and the results were favorably compared with both the limited literature data on the second normal stress difference and the predictions obtained with a recent tube-based model of entangled polymers accounting for shear flow-induced molecular tumbling. Limitations and possible improvements of the proposed simple experimental protocol are also discussed.

Improvement of the mode I interlaminar fracture toughness of glass fiber/epoxy composites using polystyrene electrospun nanofibres

In this paper, the polystyrene nanofiber (PSnF) with diameter in range 40–80 nm were fabricated using electrospinning technique from solution of polystyrene in toluene and used as an effective filler for glass fiber reinforced epoxy composite materials (GF/EP) with contents in range from 0 to 0.1 wt%. GF/EP composites with absence and presence of PSnF were characterized by different techniques, namely; mode I interlaminar fracture toughness, tensile testing and scanning electron microscope. The bonding between GF and EP were also accessed by interfacial shear strength test (IFSS). The obtained results indicated that at 0.07 wt% of PSnF incorporation in epoxy matrix the stress intensity factor (KIC), initiation and propagation interlaminar fracture toughness in mode I were improved by 42.2% from 0.631 to 0.839 MPa m1/2, and 43% from 389.82 to 512.09 J/m2 and 47% from 401.38 to 545.34 J/m2, respectively, when compared to pristine epoxy resin as well as pristine composite material. The scanning electron microscopy (SEM) observation pointed out that fibers pull out during initiation delamination accounting for fracture toughness improvement the fracture surface of GF/EP.

Iron diselenide combined with hollow graphitic carbon nanospheres as a high-performance anode material for sodium-ion batteries

A scalable method for the synthesis of iron diselenide (FeSe2) nanoparticles composited with hollow graphitic-carbon nanospheres (HGCNS) is presented. The resultant composite exhibits high sodium-ion-storage performance. A solution of iron acetylacetonate, polystyrene, and polyacrylonitrile dissolved in dimethylformamide is subjected to three continuous heat treatment steps. During this process, the amorphous carbon formed around the Fe species in the composite is selectively transformed into graphitic carbon by the catalytic action of the Fe. Residual amorphous carbon was selectively removed. Subsequent selenization of this carbonaceous material affords FeSe2-HGCNS composite. The discharge capacity of this composite is 425 mA h g−1 after 100 cycles at a current density of 0.5 A g−1, and its capacity retention compared to that in the third cycle is 94%. The excellent sodium-ion-storage performance of the composite is attributed to both ultrafine FeSe2 and HGCNS, which decrease Na+ ion diffusion length, increase electrical conductivity and allow easy penetration of the electrolyte.

A fractional dashpot for nonlinear viscoelastic fluids

In this paper, we present a fractional dashpot that is capable of continuously adjusting the degree of dissipation between the whole dashpot and the Maxwell model (spring and dashpot in serial connection). It is related to the springpot by a frequency shift of the relaxation modulus in the complex domain. In contrast to the springpot, which is a viscoelastic solid-like model, the fractional dashpot is an intrinsically viscoelastic fluid model. We demonstrate that the fractional dashpot allows one to better model the polydispersity effect of typical viscoelastic fluids, overcoming undesired stationary predictions and reducing or even eliminating multiple modes in data fitting. The linear version of the fractional dashpot model is also scaled up to large deformation by incorporation of corotational tensor derivatives and a projected strain rate tensor for constructing an objective fractional constitutive equation. The resulting model having five model parameters (one for fractionality, two for linear viscoelasticity, one for straining, and the last one for rotation) is able to fit startup shear viscosity of a high molecular weight polystyrene solution in high accuracy, and yet using only a single mode.

Phosphor Polymer Nanocomposite: ZnO:Tb3+ Embedded Polystyrene Nanocomposite Thin Films for Solid-State Lighting Applications

Producing novel functional nanomaterials with high reproducibility is extremely desirable but very challenging. Further treatment by reliably combining or embedding nanoparticles (NPs) into a protecting medium could be a promising approach to retaining their properties and realizing practical applications. In this work, we report the preparation, characterization, and potential applications of flexible and self-standing polymer nanocomposite films embedded with ZnO:Tb3+ nanophosphors suitable for optical devices. The nanocomposite films were prepared from ZnO:Tb3+ phosphor NPs synthesized by a solution combustion method and a solution of polystyrene (PS) in toluene. The structural, morphological, thermal, and optical properties of phosphor polymer nanocomposite (PS/ZnO:Tb3+) films were studied. These studies showed that the ZnO:Tb3+ phosphor NPs were uniformly distributed throughout the polymer films, providing higher stability to the thermal and photoluminescence (PL) properties of the films. The PL prop...