Polymer Blend Of Polystyrene Research Articles

The role of pore size and mechanical properties on the accumulation, retention and distribution of F98 glioblastoma cells in macroporous hydrogels

Glioblastoma (GBM) accounts for half of all central nervous system tumors. Once the tumor is removed, many GBM cells remain present near the surgical cavity and infiltrate the brain up to a distance of 20–30 mm, resulting in recurrence a few months later. GBM remains incurable due to the limited efficiency of current treatments, a result of the blood-brain barrier and sensitivity of healthy brain tissues to chemotherapy and radiation. A new therapeutic paradigm under development to treat GBM is to attract and accumulate GBM cells in a cancer cell trap inserted in the surgical cavity after tumor resection. In this work, porous gels were prepared using porous polylactide molds obtained from melt-processed co-continuous polymer blends of polystyrene and polylactide, with an average pore size ranging from 5 μm to over 500 μm. In order to efficiently accumulate and retain GBM brain cancer cells within a macroporous sodium alginate-based hydrogel trap, the pores must have an average diameter superior to 100 μm, with the best results obtained at 225 μm. In that case, the accumulation and retention of F98 GBM cells were more homogeneous, especially when functionalized with RGD adhesion peptides. At an alginate concentration of 1% w/v, the compression modulus reaches 15 kPa, close to the average value of 1–2 kPa reported for brain tissues, while adhesion and retention were also superior compared to 2% w/v gels. Overall, 1% w/v gels with 225 μm pores functionalized with the RGD peptide display the best performances.

Characterization of PS/PP/HDPE/LDPE Polymer Blend Obtained from Plastic Waste Collected on Beaches in Ilhéus-Bahia, Brazil.

A large volume of polymeric waste is generated in cities, and some of this reaches the sea and beaches. This waste stays for hundreds of years, damaging marine environments and organisms. To minimize the effects of pollution, collection and recycling allow a return to the production chain. This research aims to produce and evaluate a polymeric mixture obtained via processing plastic waste collected on the beaches of the city of Ilhéus-Bahia. Subsequently, the mixture is converted into a granulated form for application as fine aggregate in the production of cementitious matrices. A polymer blend of polystyrene, polypropylene, and high- and low-density polyethylene was obtained and evaluated by thermal, morphological, and mechanical tests in three processing stages. The degradation temperatures were close for the three processing stages and the level of processing influenced the mechanical strength. As for elastic modulus and deformation, there was no significant difference in using the mixture processed once or twice. The results showed that the reuse of the waste is applicable, the mixture presented a compact, reasonably homogeneous material with different morphology. Therefore, this work finds importance in the possibility of promoting waste recycling and adding value to a material that would become waste, thus showing its potential for application in the construction industry as an addition to cementitious mixtures and leading to savings in inputs.

Development of a nature-inspired polymeric fiber (BioFiber) for advanced delivery of self-healing agents into concrete

In this study, we developed nature-inspired multi-functional polymeric fibers (called BioFiber) to deliver bio-self-healing agents into cementitious materials. BioFibers were manufactured using a load-bearing core-fiber, a sheath of endospore-laden hydrogel, and an outer damage-responsive polymeric shell layer. The innovative BioFiber integrates three key functionalities into the quasi-brittle matrix: (i) autonomous bio-self-healing, (ii) crack growth control, and (iii) damage-responsiveness. The hydrogel sheath contained endospores, as bio-agents, to establish microbially-induced calcium carbonate precipitation (MICCP) as a self-healing end-product. The core-fibers provided crack growth control functionality into quasi-brittle engineering materials. Additionally, the outer shell coating integrated a robust damage-responsive self-healing activation strategy in concrete. A comprehensive parametric study was conducted to explore material options and the influential parameters for tailoring the processing-compositions-structure properties of the developed BioFiber. The findings of this study revealed that a concentration of 8 w/v sodium-alginate crosslinked with calcium acetate provided higher solution uptake capacity required for MICCP. As for the shell, the polymer blend of polystyrene and polylactic acid (1:1 wt%), with polymer/solvent ratio of 18 w/v-single layer coating, effectively protected BioFibers during simulated concrete casting process. Lastly, each BioFiber was able to produce 40–80 mg of calcium carbonate within the first 30 h of activation.

Development of bio-inspired multi-functional polymeric-based fibers (BioFiber) for advanced delivery of bacterial-based self-healing agent in concrete

The goal of this research is to develop innovative damage-responsive bacterial-based self-healing fibers (hereafter called BioFiber) that can be incorporated into concrete to enable two functionalities simultaneously: (1) crack bridging functionality to control crack growth and (2) crack healing functionality when a crack occurs. The BioFiber is comprised of a load-bearing core fiber, a sheath of bacteria-laden hydrogel, and an outer impermeable strain-responsive shell coating. An instant soaking manufacturing process was used with multiple reservoirs containing bacteria-laden, hydrophilic prepolymer and crosslinking reagents to develop BioFiber. Sodium-alginate was used as a prepolymer to produce calcium-alginate hydrogel via ionic crosslinking on the core fiber. The dormant bacteria (spore) of Lysinibacillus sphaericus was incorporated in hydrogel as a self-healing agent. Then, an impermeable polymeric coating was applied to the hydrogel-coated core fibers. The impermeable strain-responsive shell coating material was manufactured using the polymer blend of polystyrene and polylactic acid. The high swelling capacity of calcium-alginate provides the water required for the microbially induced calcium carbonate precipitation (MICP) chemical pathway, i.e., ureolysis in this study. The strain-responsive impermeable coating provides adequate flexibility during concrete casting to protect the spores and alginate before cracking and sufficient stress-strain behavior to grant damage-responsiveness upon crack occurrence to activate MICP. To evaluate the behavior of developed BioFiber, the swelling capacity of the hydrogel, the impermeability of shell coating, the spore casting survivability, and MICP activities were investigated.

Transport properties of polymer blends and composite membranes for selective permeation of hydrogen

Graphene Oxide (GO) dispersed in a polymer blend of Polystyrene (PS)/Poly (methyl methacrylate) (PMMA) nanocomposite membranes have been prepared by the solution cast method for hydrogen gas permeation application. This paper reports a study of blends of PMMA and PS that were prepared in different ratios of weight percentage for PMMA: PS (80:20, 50:50 and 60:40) composite with 1 wt% of GO and 2 wt% of GO. The structural and morphological properties of these prepared composite membranes have been characterized using gas permeation, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). UV Spectroscopy and FT-IR have carried out the optical absorbance measurement of the composite membranes. The permeability measurements indicate that the GO nanofillers in blends of PS/PMMA have shown higher permeability for hydrogen gas than that of pure polymers. The gases used for the permeation measurements were H2, CO2, N2 and CH4. Selectivity has been calculated for H2/CO2, H2/N2 and H2/CH4 gas pairs and plotted to show Robeson's 2008 upper bound and compared with reported data. The transport properties of these gases have been compared with that of a neat membrane. The permeability of all gases has increased to that of the unmodified polymer membrane. The selectivity measurements show that GO composite with PS/PMMA blend membranes is highly selective for hydrogen gas from different gas pairs, therefore, these composite membranes can be used for hydrogen purification. There is a trade-off between permeability and selectivity parameters; GO nanofillers keep selectivity constant as permeability increases, which the nanogap theory could explain.

Quantifying nanoscale forces using machine learning in dynamic atomic force microscopy.

Dynamic atomic force microscopy (AFM) is a key platform that enables topological and nanomechanical characterization of novel materials. This is achieved by linking the nanoscale forces that exist between the AFM tip and the sample to specific mathematical functions through modeling. However, the main challenge in dynamic AFM is to quantify these nanoscale forces without the use of complex models that are routinely used to explain the physics of tip–sample interaction. Here, we make use of machine learning and data science to characterize tip–sample forces purely from experimental data with sub-microsecond resolution. Our machine learning approach is first trained on standard AFM models and then showcased experimentally on a polymer blend of polystyrene (PS) and low density polyethylene (LDPE) sample. Using this algorithm we probe the complex physics of tip–sample contact in polymers, estimate elasticity, and provide insight into energy dissipation during contact. Our study opens a new route in dynamic AFM characterization where machine learning can be combined with experimental methodologies to probe transient processes involved in phase transformation as well as complex chemical and biological phenomena in real-time.

Dispersion and Localization Behavior of Modified MWCNTs in Immiscible Polymer Blends of Polystyrene and Polybutadiene and in Corresponding Nanostructured Block Copolymers

The influence of carbon nanotube (CNT) modification on the dispersion and localization behavior of the CNTs in immiscible blends of polystyrene (PS) and polybutadiene (PB), and in the nanostructured morphology of a star-shaped styrene-butadiene based block copolymer (BCP), was studied to form a basis for the development of functional materials with defined electrical property profiles. Unmodified multi-walled CNTs (MWCNTs) were dispersed in PS, PB and PS/PB blends by solution mixing. Additionally, MWCNTs were functionalized with n-octadecylamine and monoamino-terminated polystyrene to increase the compatibility between the homopolymers and the nanofiller. The MWCNT dispersion and the blend morphology formation were studied using transmission light microscopy and scanning electron microscopy. The MWCNT dispersion could be significantly improved by the modification of the MWCNTs. All MWCNT types were found to preferably localize in the PS phase of the PS/PB blend. However, only blends containing unmodified MWCNTs were electrically conductive. Similar effects were found in BCP/MWCNT composites. The BCP was already electrically conductive with a filler content of 0.1 wt % of unmodified MWCNTs. The stress–strain behavior of the BCP was slightly influenced by MWCNT addition and CNT modification. The dispersability of MWCNTs was significantly improved by CNT functionalization, which indicates a strong polymer-filler interaction.

Effect of Polymer Demixed Nanotopographies on Bacterial Adhesion and Biofilm Formation.

As the current global threat of antimicrobial resistance (AMR) persists, developing alternatives to antibiotics that are less susceptible to resistance is becoming an urgent necessity. Recent advances in biomaterials have allowed for the development and fabrication of materials with discrete surface nanotopographies that can deter bacteria from adhering to their surface. Using binary polymer blends of polystyrene (PS), poly(methyl methacrylate) (PMMA) and polycaprolactone (PCL) and varying their relative concentrations, PS/PCL, PS/PMMA and PCL/PMMA polymer demixed thin films were developed with nanoisland, nanoribbon and nanopit topographies. In the PS/PCL system, PS segregates to the air-polymer interface, with the lower solubility PCL preferring the substrate-polymer interface. In the PS/PMMA and PCL/PMMA systems, PMMA prefers the air-polymer interface due to its greater solubility and lower surface energy. The anti-adhesion efficacy of the demixed films were tested against Pseudomonas aeruginosa (PA14). PS/PCL and PCL/PMMA demixed films showed a significant reduction in cell counts adhered on their surfaces compared to pure polymer control films, while no reduction was observed in the counts adhered on PS/PMMA demixed films. While the specific morphology did not affect the adhesion, a relationship between bacterial cell and topographical surface feature size was apparent. If the surface feature was smaller than the cell, then an anti-adhesion effect was observed; if the surface feature was larger than the cell, then the bacteria preferred to adhere.

Facile Synthesis of Silver Hydroxyapatite (AgHAP) Reinforced Nanocomposites of Poly (styrene)‐Poly (methyl methacrylate) and Study of Their Mechanical and Blood‐Compatible Behavior

AbstractThe present work focused on the synthesis of native silver hydroxyapatite (AgHAP) nanoparticles and their reinforcement into the host matrix of binary polymer blend of polystyrene (PS) and poly (methyl methacrylate) (PMMA). The structural and morphological studies of prepared nanoparticles and AgHAP reinforced PS‐PMMA nanocomposites were performed by various characterization techniques like Fourier transform infrared (FT‐IR) and Raman spectroscopy, X‐ray diffraction, atomic force microscopy (AFM), and Field emission scanning electron microscopy (FESEM). The particle size analysis and zeta potential measurements were used to confirm nanosize of the AgHAP nanoparticles and their surface charges. The mechanical properties of AgHAP/PS/PMMA nanocomposites, such as microhardness and compressive strength, were also determined. The blood compatibility tests were performed to investigate biocompatible nature of the nanocomposites. The antibacterial property of the nanocomposites was also studied against S. aureus and E. coli species and the cytotoxic nature of the nanocomposites was conducted following 3‐(4,5‐Dimethylthiazol‐2‐Yl)‐2,5‐Diphenyltetrazolium Bromide (MTT) assay test.

Compatibilization and mechanical properties of compression-molded polypropylene/high-impact polystyrene blends

This research work focused on polypropylene/high-impact polystyrene polymer blends. Since this blend (80/20 in weight) was incompatible, styrene–ethylene–butylene–styrene (SEBS) block copolymer, styrene–butadiene–styrene (SBS), and ethylene vinyl acetate were tested as compatibilizers (2.5 or 7.5 wt% in relation to blend). After blending via extrusion, the compositions were compression molded and their mechanical (tensile and impact), morphological (scanning electron microscopy), and rheological (melt flow index and viscosity) properties were evaluated. Blends containing SBS and 7.5 wt% of SEBS showed a positive effect regarding impact strength, although with a decrease in Young’s modulus and tensile strength. Rheological characteristics were also affected by the compatibilizers.

Unravelling the surface composition of symmetric linear-cyclic polymer blends

We perform molecular dynamics computer simulations of free-standing films of symmetric binary linear-cyclic polymer mixtures at equimolar composition. We show that the density of linear polymers at the free-surface is enhanced with respect to the bulk value for short chains, but it is depleted for long chains. Our findings suggest that the enhancement of the composition of linear chains reported for polystyrene polymer blends might hold in a more extended composition range than the one considered in previous experiments at the free surface. Focusing on the equimolar regime of the two polymer species with the identical chain length allows us to safely conclude that the observed surface deviations from the bulk are driven by the topological differences between the two polymer species, and rule out any role played by the different concentration of the two polymer species.

Enhanced phase and amplitude image contrasts of polymers in bimodal atomic force microscopy

Higher second free amplitudes beyond the commonly used values show remarkable phase and amplitude contrasts.

A Small-Scale Experimental Extrusion Set-Up for Exploring Relationships Between Process-Induced Structures and Characteristics of Multiphase Polymer Systems

Taking immiscible polymer blends of polystyrene (PS)/poly(methyl methacrylate) (PMMA) as a case study, we present the capabilities of a small-scale experimental extrusion set-up for sightseeing the morphological evolution during processing and identify relationships between process-induced structure, blend rheology, and product (extruded sheet) properties. In-line rheo-optical data collected with an instrumented slit die coupled to the small-scale extrusion line are in agreement with the results reported elsewhere for model polymer blends studied with simpler and slower flow fields with less relevance to industrial application. Shear stress and first normal stress difference transients relate to the stretching, orientation, break up, and subsequent string arrangement of droplets probed in the die by in-line polarized optical microscopy and small-angle light scattering. The partially relaxed droplet morphology in extruded sheets has no impact on their mechanical properties which are essentially linked to those of PS and PMMA.

Preparation and Characterization of Subsurface Silver Particulate Films on Polymer Blends of Polystyrene/Poly(2-vinylpyridine)/Poly(vinylpyrollidone)/Poly(4-vinylpyridine)

Silver particulate thin films on softened polymer blends of Polystyrene (PS)/Poly(2-vinyl pyridine) (P2VP), PS/Poly(4-vinylpyridine) (P4VP), and Poly(vinylpyrollidone) (PVP)/P4VP at a rate of 0.4 nm/s held at a temperature of 457 K in vacuum of 8 × 10-6 Torr by evaporation are deposited. These silver films were characterized by their electrical behavior, optical properties and Scanning electron microscopy (SEM). Silver films deposited on softened PS, and PVP give rise to a very high room temperature resistance approaching that of the substrate resistance due to the formation of a highly agglomerated structure. On the other hand, silver films on softened P2VP and P4VP give rise to a room temperature resistance in the range of tens to a few hundred MΩ/ which is desirable for device applications. Silver films on the composites of PS/P2VP, PS/P4VP and PVP/P4VP show resistances at room temperature. The optical and plasmonic response of Ag nanoparticles onto thin layers of blends shows encapsulation of nanoparticles. The electrical properties and SEM of silver nanoparticles on the thin layers of polymer blends indicate the formation of much smaller, narrower dispersion and wide size distribution.

Effects of HIPS on the Sound Absorption and Impedance Ratio of SEBS/HIPS/CaCO3 Polymer Composites

A sound absorption material composed of styrene ethylene butadiene styrene, high impact polystyrene and CaCO3 has been developed. Its sound absorbing characteristic was investigated in the impedance tube, according to transfer function method. Measurements show that HIPS ratios have effect on the absorption performance of the blend because of their microstructures and features. The structure and properties of the blend is characterized using a scanning electron microscopy (SEM). Furthermore, styrene ethylene butadiene styrene and high impact polystyrene polymer blend was subjected to examinations to obtain their hardness and Izod impact strength. When the sound absorption characteristics of the materials are examined, a unsteady behaviour is observed up to the level of 1600 Hz. It is determined that sound absorption characteristics of all materials increase after this point. A high and steady behaviour is observed, particularly after 4800 Hz.

Quantitative Image Analysis of Broadband CARS Hyperspectral Images of Polymer Blends

We demonstrate that broadband coherent anti-Stokes Raman scattering (CARS) microscopy can be very useful for fast acquisition of quantitative chemical images of multilayer polymer blends. This is challenging because the raw CARS signal results from the coherent interference of resonant Raman and nonresonant background and its intensity is not linearly proportional to the concentration of molecules of interest. Here we have developed a sequence of data-processing steps to retrieve background-free and noise-reduced Raman spectra over the whole frequency range including both the fingerprint and C-H regions. Using a classical least-squares approach, we are able to decompose a Raman hyperspectral image of a tertiary polymer blend into quantitative chemical images of individual components. We use this method to acquire 3-D sectioned quantitative chemical images of a multilayer polymer blend of polystyrene, styrene-ethylene/propylene copolymer, and polypropylene that have overlapping spectral peaks.

Morphology of silver particulate films deposited on softened polymer blends of polystyrene and poly (4‐vinylpyridine)

AbstractResults of the morphological studies of silver particulate films deposited at a rate of 0.4 nm/s on polymeric blends of polystyrene (PS) and poly (4‐vinylpyridine) (P4VP) held at a temperature 457 K by evaporation in a vacuum of 8 × 10−6 Torr are reported here. The morphology of silver particulate films was characterized by their size, size distribution, shape and interparticle separation. It has been observed that morphology depends on the composition of polymer matrix and the amount of silver deposited. The red shift in the plasmon resonance was observed with the increasing amount of P4VP in the blends in comparison to the pure PS. This indicates the modification in the silver particulate films deposited on the PS/P4VP blends. Scanning electron microscopy (SEM) was used to study the change in morphology of the silver nanoparticles and was correlated with the optical properties of silver particulate films on PS/P4VP blends. The silver nanoparticles deposited on the thin layers of polymer blends exhibit smaller size with narrower dispersion and wider size distribution due to blending of P4VP with PS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effect of recycling on rheological and mechanical properties of poly(lactic acid)/polystyrene polymer blend

A continued increase in the use of plastics has led to an increasing amount of plastics ending up in the waste stream; and the increasing cost of landfill disposal and public interest in support of recycling has meant that plastics recycling must increase. In this work, the effect of multiple extrusion and injection of poly(lactic acid)/polystyrene polymer blend (PLA/PS) on its rheological and mechanical properties is presented. Rheological properties were studied using a capillary rheometer, apparent shear rate (γ a), apparent shear stress (τ a), apparent viscosity (η a), and flow activation energy were determined. The mechanical properties of the blend were investigated on dog bone-shaped samples obtained by injection molding, tensile tests were performed, stress at break, strain at break, and Young’s modulus were determined. The results showed that the apparent viscosity of PLA/PS blend decreases monotonously with increasing the processing number. Also it was found that stress and strain at break of the blend decrease sharply after two processing cycles, whereas the processing number has a little effect on Young’s modulus.

Rheological and mechanical properties of poly(lactic acid)/polystyrene polymer blend

Properties modification by blending polymers has been an area of immense interest. In this work, rheological and mechanical properties of poly(lactic acid)/polystyrene (PLA/PS) blends were investigated. PLA/PS blends in different ratios were prepared using a laboratory scale single screw extruder to obtain (3 mm) granules. Rheological properties were studied using a capillary rheometer and the Bagley’s correction was performed. True shear rate (γr), true shear stress (τr), and true viscosity (ηr) were determined, the relationship between true viscosity and (1/T) was studied for PLA70 blend and the flow activation energy at a constant shear stress (Eτ) and a constant shear rate (Eγ) was determined. The mechanical property measurements were performed at room temperature. Stress at break and strain at break were determined. The results showed that PLA/PS blend exhibited a typical shear-thinning behavior over the range of the studied shear rates, and the viscosity of the blend decreased with increasing PLA content. Also it was found that no equal-viscosity temperature exists between PLA and PS. The mechanical results showed immiscibility between PLA and PS in the blend.

Influence of polystyrene/phenyl substituents in precursors on microstructures of Si–O–C composite anodes for lithium-ion batteries

Pyrolysis of methylphenyl-substituted branched polysilane–polystyrene polymer blends led to the formation of silicon oxycarbide (Si–O–C) glasses with microstructures similar to those found in hard carbon. Electrochemical measurements showed that the Si–O–C composite materials had lithium storage capacities of more than 500 mA h g −1, with a short but characteristic pseudo-voltage plateau at ca. 0.1 V upon delithiation. This voltage plateau indicates the existence of micropores where less-ionic lithium species can be formed, as seen in the case of hard carbon. The micropores were minor electrochemically active sites but led to an increase in the capacities. 7Li NMR spectra of the Si–O–C composite materials had two resonances in the fully lithiated state, and one resonance could be attributed to less-ionic lithium species in the micropores. No voltage plateau was observed upon delithiation, and only a singular 7Li NMR resonance was observed when the polysilanes alone were pyrolyzed. Although there was no decrease in the capacities, the voltage plateau disappeared with electrochemical cycling. Furthermore, different 7Li NMR resonances from those observed in the first lithiation were clearly seen. These results indicate changes in the lithium environments in the Si–O–C composite materials.