Polystyrene Phase Research Articles

Planar Orientation and Transparency of Nanoporous-Crystalline Polymer Films

The dependence of polymer film transparency on different kinds of planar orientations of nanoporous-crystalline (NC) phases of syndiotactic polystyrene (sPS) and poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) is described. The two polymers exhibit opposite behavior: film transparency is improved for sPS and PPO by orientations of the chain axes of the NC phases being parallel (c∥) and perpendicular (c⊥) to the film plane, respectively. This behavior can be rationalized by the negative and positive birefringence of sPS and PPO chains, respectively. In fact, to maximize transparency, the refractive index of the NC phase along the perpendicular to the film plane has to be increased to come closer to that of the corresponding amorphous phase. This can be pursued by controlling the orientation of the NC phases and hence of the associated refractive index ellipsoids.

Thin film composite solvent resistant nanofiltration membrane via interfacial polymerization on an engineered polyethylene membrane support coated with polydopamine

In this work, a thin film composite (TFC) membrane possessing outstanding properties for solvent resistant nanofiltration (SRNF) membrane application was fabricated. For this purpose, high density polyethylene (HDPE)-polystyrene (PS)-styrene-ethylene-butylene-styrene (SEBS) blends were fabricated in the first step with different compositions by using an internal mixer machine and hot press technique, respectively. Then, the fabrication of a novel HDPE support was conducted by etching the PS phase out of the as-prepared HDPE-PS-SEBS blends through solvent extraction method (Etched HDPE). In the next step, the prepared Etched HDPE membrane support was dipped in a dopamine solution, by which auto-oxidization and self-polymerization of dopamine monomers onto the Etched HDPE membrane supports surface was done, leading to the formation of an ultrathin polydopamine (PDA) layer with a strong chemical binding force. By the formation of the polydopamine layer, hydrophilic functional groups were introduced onto the HDPE membranes surface, causing the attraction of m-phenylenediamine (MPD) monomers onto the membrane surface and the formation of a uniform ultrathin PA top layer. Finally, the TFC layer was formed on the as-prepared membrane supports with different m-phenylenediamine and trimesoyl chloride (TMC) concentrations. The performance and properties of the prepared TFC-PE@PDA membrane was investigated for rejection of different dyes including Reactive Red, Direct Yellow, Methyl Blue, Rhodamine B, Crystal Violet and Methyl Orange in SRNF applications, based on which outstanding separation performance (dye rejections of 99.8, 99.5, 99.2, 98.5, 96.8 and 94.4 for RR, DY, MB, RDB, CV and MO, respectively, under the pressure of 9 bar), methanol flux as high as 1.8 L/m2 h bar along with excellent methanol flux as high as 3.7 L/m2 h bar after Dimethylformamide activation, were obtained. Furthermore, it is noteworthy that an outstanding solvent resistance (dye rejections of more than 99.2, 98.8, 98.5, 97.9, 96 and 93.8% for RR, DY, MB, RDB, CV and MO, respectively, being dipped in Dimethylformamide at 70 °C for 90 days) was also shown by the prepared TFC-PE@PDA membrane.

Stationary Phases for Capillary Gas Chromatography Obtained on the Basis of Hypercrosslinked Polystyrenes

Capillary columns with previously or in situ synthesized super-crosslinked polystyrene phases are prepared. It has been shown that columns with stationary phases based on presynthesized hypercrosslinked polystyrenes, spherical monodisperse particles, or “nano-sponges,” despite their microporous structure, show insufficient kinetic efficiency and selectivity in the separation of light hydrocarbons. Higher kinetic efficiency was observed in columns where the hypercrosslinked polystyrene phase was synthesized directly in the column, although the porosity structure of this phase remains unknown. All columns with hypercrosslinked polystyrene stationary phase have good thermal stability, with no observed chemical destruction and physical aging at temperatures up to 250°C.

Capillary Action-Inspired Nanoengineering of Spheres-on-Sphere Microspheres with Hollow Core and Hierarchical Shell.

The current syntheses of spheres-on-sphere (SOS) microsphere, which possesses both hollow cavity and hierarchical structure, mainly rely on complicated routes and template removal. In this study, a one pot nanoengineering strategy inspired by the automatic transport behavior of water in plants is successfully developed to fabricate SOS microsphere in tandem with a traditional soft template method in the preparation of hollow structure. Amphiphilic siloxane oligomers generated in situ from methyltriethoxylsilane (MTES) under acidic conditions are anchored on the surface of soft template St monomer droplets, sequentially completing hydrolysis-polycondensation and forming a mesoporous polysilsesquioxane (PSQ) shell. Then, the St monomers located in cavity migrate outward under the combined action of capillary force stemming from mesoporous and osmotic pressure generating from inside-outside of the PSQ shell and polymerize on the outside of the hollow PSQ shell, in which residual siloxane oligomers further anchor on the polystyrene (PS) surface to reduce the surface energy of the system, finally resulting in the successful formation of SOS particles. To reduce thermal insulation coefficient of the material, the PS phase in SOS particles is removed to obtain the particles with multiscale hollow structure (SOS-MH), which have more hollow cavities to encapsulate more air. The presence of a much hollow structure in SOS-MH particles enables the thermal conductivity of polyacrylonitrile (PAN)/SOS-MH composite fibrous membranes (0.0307 W m-1 K-1) to decrease by about 40% compared to that of pure PAN fibrous films (0.0520 W m-1 K-1) at the same thickness of 1 mm, and the material also has moisture resistance due to the existence of a hierarchical shell.

Well dispersion of poly(acrylonitrile‐butadiene‐styrene) in isotactic polypropylene mediated by incorporation of graphene and the elevated toughness

Polymers with benzene rings in structures including polystyrene (PS) and poly(acrylonitrile‐butadiene‐styrene) (ABS) could function as rigid organic particles and macromolecular β nucleating agents to toughen isotactic polypropylene (iPP), and the toughening effect mainly depends on their dispersibility in iPP matrix. In this work, a third component of graphene (G) was introduced into the iPP/PS and iPP/ABS blends, respectively, to mediate the dispersibility of these polymers in the iPP via melt blending. Selective dispersion of graphene in these immiscible blends has been investigated with SEM, DSC, and a rheometer. It was interesting to obtain a more favorable dispersion of ABS in the iPP/ABS/G blend compared with the iPP/ABS blend, and the corresponding toughness showed a prominent improvement accompanied with an elevation in rigidity. The underlying mechanism for the improved dispersion of ABS in the iPP/ABS/G blends has been discussed in detail. However, because of a better affinity of the graphene to the PS than the iPP matrix, graphene could only locate in the PS phase, resulting in poor compatibilization for the iPP/PS blend followed by the deterioration of mechanical properties.

Bilayer PMMA antireflective coatings via microphase separation and MAPLE

Abstract A poly(methyl methacrylate) (PMMA) bilayer antireflective coating (ARC) is designed based on polymeric microphase separation and matrix-assisted pulsed laser evaporation (MAPLE). The spin-coated layer shows subwavelength porous network structures, after phase separation via annealing and removal of the polystyrene (PS) phase, while the MAPLE deposited surface layer exhibits a biomimic moth-eye structure on glass to trap the incident light. The elaborate spin coated structure can be controlled flexibly by changing the ratio of mixture, annealing time and temperature, and the moth-eye structure can also be tuned by deposition parameters. The transmittance of the ARC presents a maximum of 95.64% and an average of 94.81% in visible range. The moth-eye structure on glass substrate formed by nanoglobules makes positive contributions to the improvement of transmittance according to UV–Vis result and simulation. The wetting motion of PMMA globules is observed as well by the comparison of AFM surface morphologies and cross-sectional profiles of globules on glass and polymer thin film. This work is a novel attempt to fabricate bilayer ARC with two different structures by a single polymeric material and will provide new route for fabrication of multilayer ARCs.

Porous Fe3O4 submicron particles for use in magnetorheological fluids

The magnetorheological (MR) performance and stability of various suspensions based on core-shell-structured polystyrene(PS) / Fe3O4 particles, the Fe3O4-coated particles, the hollow and porous Fe3O4-particles were investigated by using a rotational rheometer and Turbiscan, while magnetic properties of all the magnetic particles used were examined by using a vibrating sample magnetometer (VSM). The PS (core)/Fe3O4(shell) was synthesized by the Pickering-emulsion polymerization method using Fe3O4 nanoparticles as a solid surfactant. Hollow and porous Fe3O4 nanoparticles were obtained after extraction of the core PS phase by Soxhlet extractor. The density of the hollow Fe3O4 nanoparticles was markedly decreased compared to that of pure Fe3O4, but slightly increased compared to that of the PS/Fe3O4 particle. All suspensions, prepared by dispersing the synthesized particles in the liquid medium (silicone oil), exhibited similar MR behaviors, but the MR performance of the hollow and porous Fe3O4 particle suspension was remarkably better than that of the PS/Fe3O4 particle suspension. The hollow Fe3O4 particle suspension showed a significantly better stability than the pure Fe3O4 particle suspension due to the reduced density mismatch between the particle and the liquid medium and the rough and bumpy surface morphology. The optimal density for the MR performance and the suspension stability was determined from the MR property analysis.

Preparation of Cylindrical Janus Particles Using a Stirring Method.

We previously discovered a novel method for the preparation of polymer particles that have a cylindrical shape. Polystyrene (PS) or poly methyl methacrylate (PMMA) spherical particles were deformed into a cylindrical shape by stirring with a magnetic stirrer in a polyvinylpyrrolidone (PVP) aqueous solution. In this study, cylindrical “Janus” particles consisting of PS and PMMA were prepared by this stirring method. In the case of spherical Janus particles, cylindrical particles were obtained after stirring; however, the direction of the interface between the PS and PMMA phases was random. However, in the case of snowman-like Janus particles, cylindrical Janus particles with the interface at the center of the long axis were successfully prepared. This indicated that the extension direction can be controlled owing to the anisotropic shape and supported the proposed deformation mechanism of the cylindrical particles. Moreover, amphiphilic cylindrical Janus particles were also successfully prepared by hydrolysis of only one phase to introduce carboxy groups.

Influences of high‐impact polystyrene loading on the foaming behavior andflame‐retardantproperties of polyphenylene oxide composites blown withCO2

AbstractPolymeric foam with high expansion ratio, well‐defined cell structure, and excellent flame retardant properties is essential for broadening its applications. Polyphenylene oxide (PPO) is a kind of cost‐effective engineering plastic with excellent flame retardancy, anti‐dripping behavior, and good mechanical strength, but suffers from its poor processability. In this study, microcellular PPO composite foams were fabricated by applying a solid‐state foaming technology using compressed CO2as the blowing agent. High‐impact polystyrene (HIPS) phase was introduced with the aim to improve the fluidity and foaming ability of PPO composites. It was interesting to find that the 18–48% HIPS loading significantly increased the expansion ratio, that is, 1.8–3.3 versus, 10.8–14.3, and broadened the optimum foaming temperature of PPO composite foams, attributing to the miscible character between PPO and HIPS and excellent foaming ability of HIPS. Furthermore, the as‐prepared PPO/HIPS composite foams exhibited high limited oxygen index (LOI) of 22.0–29.9%, low horizontal flammability rate (HFR) of 60.5–141.2 mm/min, and anti‐dripping behavior, and the void fraction was verified to be a critical parameter to determine the flame retardant performance of the composite foam. Besides its lightweight and excellent flame retardant properties, PPO composite foams also presented uncompromised tensile properties and well‐defined thermal insulation properties.

The ways of connecting crystalline phases having tubular cavities like stringing beads: New conductive polymer composites prepared by the polymerization of aniline in highly oriented ε crystalline phase of syndiotactic polystyrene

We prepared the syndiotactic polystyrene (SPS) films such that its ε crystalline phase and its channeling cavity were oriented to be parallel to the direction of the film thickness with a high regularity. Moreover, we introduced aniline molecules to these oriented cavities and successfully polymerized them to polyaniline (PANI). This is the mild and intelligent way of preparing polymer composites where the orientation and arrangements of the polymers are highly controlled. These SPS/PANI films showed the electrical conductivity to be ~0.05 S/cm and the maximum molecular weight of PANI to be 30 units of aniline. Interestingly, the film thickness was found to increase by 110–200%. This is because some ε crystalline phase is connected by the polymerization of aniline in the cavity, like sewing beads (some SPS ε crystalline phase) with a thread (polymerizing PANI). The paper examined the reaction temperature of aniline in SPS films, and other properties such as conductivity, molecular weight, and yield of PANI.

Chain Extension, Phase Interface Reparation and Mechanical Property of Recycled Acrylonitrile‐Butadiene‐Styrene by Epoxidized Styrene‐Butadiene‐Styrene

AbstractThe demand for processing recycled acrylonitrile‐butadiene‐styrene copolymer plastics (R‐ABS) grows fast. Herein, epoxidized styrene‐butadiene‐styrene (ESBS) with reactive groups including polybutadiene (PB) phase, epoxidized polybutadiene (EPB) phase and polystyrene phase is prepared by modifying SBS with an in situ peroxyformic acid method. Both chain extension and phase interface reparation of R‐ABS are successfully reported by simple melt blending. Compared with R‐ABS, when ESBS content is 15 wt%, the average molecular weight (Mw) of the ESBS/R‐ABS is increased from 118.01 to 612.51 kDa. The particle size of the dispersed phase is decreased obviously. The compatibility between these two phases became better. The average notch impact strength of R‐ABS is 5.72 kJ m−2. When the ESBS content is 15 wt%, the average notch impact strength of ESBS/R‐ABS reaches 13.90 kJ m−2, which is increased by 143% compared with that of R‐ABS. The notch impact strength of ESBS/R‐ABS is close to that of virgin ABS. The reported high‐value usage of R‐ABS has a great potential for industrial‐scale applications.

Morphology, thermal behavior, rheological, and mechanical properties of polypropylene/polystyrene blends based on elongation flow

Binary blends comprised of polypropylene (PP) and polystyrene (PS) were prepared by a novel eccentric rotor extruder based on elongation flow. The morphology, thermal behavior, rheological and mechanical properties were investigated. As the enhanced mixed dispersion based on the novel extruder, the dispersed PS phase were uniformly dispersed in the PP matrix when the PS not more than 40%, and a distinct cocontinuous phase structure emerged when the PS content was 50%. The size of the dispersed PS phase related to the PS content and the processing flow filed influenced the crystallization behavior and the thermal stability of the blends. The PS droplet with small size could act as a nucleating agent for PP to improve the crystallinity, and PS droplet with large size could promote the thermal and heat transfer between the PS droplets and PP matrix which decreased the thermal stability. The rheological results showed that the compounding with PS into the PP matrix increased the storage and loss modulus as well as the complex viscosity of the materials. When the PS content not more than 20%, the blends showed good impact resistance, and PP/PS blends 30% PS showed good tensile and flexural properties. This study gives a new perspective for the structure and properties of the binary PP/PS blends prepared based on elongation flow.

Robust cellulose nanofibrils reinforced poly(methyl methacrylate)/polystyrene binary blend composites with pebble‐shaped structure using Pickering emulsion gel

Both poly(methyl methacrylate) (PMMA) and polystyrene (PS) have excellent transparency, but a blend of the two typically has low mechanical properties and poor transparency owing to phase separation. Herein, oil‐in‐water Pickering emulsion gel technology was combined with the hot pressing process to prepare cellulose nanofibrils (CNFs) reinforced PMMA/PS binary blend composite film materials (CNFs/PMMA/PS). The CNFs/PMMA/PS composites with a pebble‐shaped structure had a unique three‐dimensional crosslinked network structure and endowed the composite film with better thermal stability, and excellent transparency and mechanical properties. Particularly, the derivative thermogravimetry and differential scanning calorimetry results revealed that the compatibility between the PMMA and the PS phases in the composite film is remarkably improved. The optimal tensile strength (58 MPa) and maximum strain (4.2%) were obtained when the content of CNFs was 52%, which represented approximately 3‐fold and 2‐fold improvements, respectively, than those of the PMMA/PS blend films. Moreover, the C‐CNFs/PMMA/PS composite films maintained an excellent light transmittance of approximately 80% in the wavelength range of 600 to 800 nm. The facile preparation method is proposed to achieve an excellent dispersion of unmodified CNFs in hydrophobic and binary polymer mixture, which constitutes a new approach for using CNFs to enhance the high performance of polymer materials.

Rheology and foaming behaviour of styrene–ethylene–butylene–styrene nanocomposites

The dependence of the foaming behaviour of a polymeric material on its material characteristics and foaming temperature gives rise to the research question that how the degree of dispersion/distribution of nanoparticles and the resulting viscosity changes affect the foaming behaviour and properties of nanocomposite foams. In the study reported here, styrene–ethylene–butylene–styrene was selected as a model polymer, because of its complex microstructure and its commercial importance. Styrene–ethylene–butylene–styrene nanocomposites, with different nanoclay loadings, were processed in a twin-screw extruder. The nanocomposite structure was correlated with the rheological properties to evaluate the batch-foaming performance of nanocomposite using carbon dioxide at different temperatures. At 35 °C, selective foaming of the elastomeric phase, hindered by the stiff polystyrene phase, resulted in foams with more than 74% shrinkage. At 80 °C, higher viscosities and moduli resulted in foams with higher volume expansion ratios. Increases in the degree of delamination of silicate layers in nanocomposites resulted in cell sizes up to 41% and 75% lower than that of neat polymer foams produced at 35 °C and 80 °C, respectively. Dynamic mechanical analysis results suggest heterogeneous nucleation and the presence of nanoclay in both phases. The study results show that the nanocomposite structure plays an important role in the production of thermoplastic elastomer foams of superior morphology and low shrinkage.

Preparation of tough, high modulus, and creep-resistant PS/SIS/halloysite blend nanocomposites

In this work, polystyrene (PS)/poly(styrene-b-isoprene-b-styrene) (SIS)/organophilic halloysite nanotube (Org-HNT) blend nanocomposites were produced by melt compounding technique. The significant improvements in both toughness and impact strength values were obtained in PS/SIS blends containing 20%, 30%, and 40% SIS elastomer as compared to neat PS. Among them, PS-30SIS blend with a co-continuous morphology exhibited moderate tensile and impact properties and its nanocomposites having 3, 5, 7 and 10 phr Org-HNT were prepared through the melt mixing method. All the nanocomposites exhibited continuous/fibrillar morphologies with smaller elastomer domains and higher tensile modulus and toughness as compared to PS-30SIS blend. Among them, the nanocomposite having 7 phr Org-HNT and 30% SIS phase (7H-30SIS) exhibited the highest impact strength with enhanced tensile properties. The same nanocomposite exhibited about 21% and 100% increments in the modulus and toughness in comparison to its blend, respectively. The 7H-30SIS nanocomposite increased storage moduli of PS-30SIS blend at glass transition regions of both polyisoprene and PS phases and also at room temperature. Moreover, the rubbery storage moduli of the nanocomposites were found to be about 37% and 53% higher for 7 and 10 phr Org-HNT loaded nanocomposites, respectively, in comparison with that of PS-30SIS blend. The creep deformation and permanent deformation of the blend both decreased via introduction of the nanotubes which is in agreement with aforementioned improvements in the stiffness.

Rheological Properties and Phase Structure of Polypropylene/Polystyrene/Multiwalled Carbon Nanotube Composites

In this work, nanocomposites of polypropylene (PP)/polystyrene (PS)/multi-walled carbon nanotube (MWCNT) were prepared by the sonochemical polymerization of styrene in the presence of PP and MWCNT. This procedure offered a composite (PP-g-PS/MWCNT) having a unique phase structure in which MWCNTs are distributed in both phases of PP and PS, which is contrary to the typical observations in the composites made by the melt blending process (PP/PS/MWCNT) where MWCNTs are preferentially located in PS phase. It is shown that the PP-g-PS/MWCNT samples exhibit a strong solid-like behavior and viscosity upturn at a low-frequency range whose extent increases with MWCNTs content, while such features are not significant in the case of PP/PS/MWCNT. In addition, it is demonstrated that the storage modulus measured from dynamic mechanical analysis and electrical conductivity of PP-g-PS/MWCNT are also superior to those of PP/PS/MWCNT at the same loadings of MWCNTs, which can be attributed to the state of MWCNTs dispersion and their localization behavior in the biphasic systems of PP and PS.

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.

An Effective Strategy to Achieve Ultralow Electrical Percolation Threshold with CNTs Anchoring at the Interface of PVDF/PS Bi‐Continuous Structures to Form an Interfacial Conductive Layer

AbstractConductive composites based on polymers and conductive nanofillers are widely studied as a promising material. The rational design of 3D conductive networks in composites is crucial to improve their electrical conductivity and reduce the dosage of nanofillers. Herein, poly(vinylidene fluoride) (PVDF) and polystyrene (PS) bi‐continuous structures with modified carbon nanotubes (CNTs) tailored to anchor at the interface are designed to achieve an ultralow electrical percolation threshold because of the formation of a thin interfacial conductive layer. In this work, the modification of CNTs with poly(methyl methacrylate) (PMMA), which contributes to the improvement of the compatibility between PVDF and CNTs, is effective to control the distribution of CNTs in composites. It promotes the migration of CNTs from the PS phase to the interface of PVDF and PS. Consequently, the interfacial conductive layer is formed at a low CNT content, and the electrical percolation threshold of PVDF/PS/CNTs‐PMMA nanocomposites is only 0.07 vol%, having a great decrease of about 50% compared with that of PVDF/PS/CNTs nanocomposites. Thus, it is demonstrated that the distribution of CNTs can be tailored to anchor at the interface by proper chemical modification to form an interfacial conductive layer and a decrease of percolation threshold can also be achieved.

Application of Ethylene-α-olefin Co-oligomers to Functional Compounds

The effect of blending ethylene-α-olefin co-oligomer as a modifier with polystyrene-block-poly[ethylene-co-(ethylene-propylene)]-block-polystyrene (SEEPS) triblock copolymer/polypropylene (PP) compounds was investigated. Compared with mineral oil, ethylene-α-olefin co-oligomer improved the compression set (CS) and the permanent set (PS) of the compound and increased the fracture strength of the compound. Small-angle X-ray scattering (SAXS) measurements showed that the ethylene-α-olefin co-oligomer was localized at the center of the poly[ethylene-co-(ethylene-propylene)](EEP) phase, while the mineral oil was widely distributed in the EEP phase and reached even near the interface between the polystyrene (PSt) phase and the EEP phase. This suggests that, in the case of the ethylene-α-olefin co-oligomer, the stress of the EEP block chain can be kept during the deformation more than in the case of the mineral oil, resulting in the good properties of CS and PS.

Reinforced and toughened PP/PS composites prepared by Fused Filament Fabrication (FFF) with in-situ microfibril and shish-kebab structure

In this work, in-situ microfibrillar composites (MFC) of polypropylene (PP)/polystyrene (PS) were produced by Fused Filament Fabrication (FFF) with a self-designed build platform. Due to the high shearing and stretching effect during the FFF process, PS phase underwent a large deformation. A large number of PS microfibrils could be observed in the samples. Meanwhile the molecular chain of PP was also stretched and arranged along the flow direction in the 3D Printing process. Finally, microfibrils, shish-kebab and hybrid shish-kebab crystal structures can be found and they make contributions to the mechanical performance. This work confirms the applicability of semi-crystalline polymer in FFF technology and discusses the development of phase morphology and crystalline morphology during printing. These obtained results will provide new ideas for broadening the amount of available materials and the application fields of FFF samples.