Prepared Polystyrene Research Articles

Synergetic effect of nanoclay and nano-CaCO3 hybrid filler systems on the foaming properties and cellular structure of polystyrene nanocomposite foams using supercritical CO2

Supercritical fluids have been widely used to prepare various polymer nanocomposite foams due to their high-efficiency, rich-resource, and environment-friendly characteristics. In this work, we prepared polystyrene (PS) nanocomposites with different contents of hybrid fillers of nanoclay and nano-calcium carbonate (nano-CaCO3) and then were foamed by batch foaming method using supercritical carbon dioxide as a physical blowing agent. The effect of hybrid nanofillers components and foaming temperature and pressure on the foaming properties and cellular structure of PS nanocomposite foams was systematically investigated. Dynamic rheology results indicated that the complex viscosity and storage modulus were enhanced with the addition of hybrid fillers. Scanning electron microscopic images show that all samples foamed uniformly macrocells under the given conditions. More importantly, the hybrid fillers of nano-CaCO3 and nanoclay exhibit a significant synergistic effect in improving PS foaming properties, which can be ascribed to the different roles of the two fillers during cell nucleation and cell growth. For instance, the PS/0.22/0.88 nanocomposite foamed under the conditions of 20 MPa and 130°C has shown the finest cell structure (higher cell density of 1.91 × 1010 and smaller cell diameter of 2.28 µm) due to the coeffect of the hybrid nanofillers. Finally, the synergistic mechanism of these two nanofillers on PS foaming behavior was discussed.

Facile and Affordable Process to Control Shell Thickness of Polydopamine-Assisted Polystyrene/Silver Core-Shell Particles

We prepared polystyrene (PS)/silver (Ag) core-shell particles with an excellent electrical conductivity in a facile, affordable and eco-friendly way. As core particles, monodisperse PS particles were synthesized by the process of dispersion polymerization. Then, the PS particles were coated with polydopamine (PDA) through the spontaneous oxidative polymerization of dopamine to produce PDA-coated PS particles. In essence, it is noted that the catechol and amine groups of PDA coated on PS particles can weakly reduce metallic ions. As a secondary reducing agent with an affordable price, glucose was therefore added to promote the reduction of metallic ions. Herein, the effect of glucose concentration on the Ag shell thickness of PDA-assisted PS/Ag core-shell particles was investigated. The degree of Ag reduction increased with an increase characteristically in glucose concentration, resulting in the increase of Ag shell thickness. Notably, a thick and uniform Ag shell layer could be plated on PDA-coated PS particles, which were noted to have rendered excellent electrical conductivity. When the glucose concentration of 55 mM was applied, the electrical conductivity of the PS/Ag core-shell particles reached as high as 7.8×105 S/m, which was almost close to that of conductive metals.

Исследование адгезии эндотелиоцитоподобных клеток EA.hy926 к различным подложкам, используемых в методе мягкой литографии для создания микрофлюидных чипов

Адгезия клеток к субстрату является одним из ключевых факторов, влияющих на клеточные функции и их жизнеспособность. Для адекватного биомоделирования многоклеточных тканевых структур in vitro необходим тщательный подбор используемых в качестве подложки для клеток материалов. В работе мы исследовали адгезию эндотелиоцитоподобных клеток EA.hy926 к стеклу и полимерным материалам, часто применяемых в микрофлюидике для моделирования тканевых структур. Методом конфокальной сканирующей микроскопии было показано, что различные виды полидиметилсилоксана (ПДМС) характеризуется низкой адгезией клеток по сравнению со стеклом и специально подготовленным полистиролом (ПС). При этом обработка кислородной плазмой не оказывает существенного влияния на адгезию. Обработка коллагеном I, напротив, существенно улучшает адгезию. Белковый гель достаточно хорошо покрывает как гидрофильную поверхность стекла, так и гидрофобную поверхность полимера. Методом сканирующей зондовой микроскопии были также исследованы особенности распластывания отдельных клеток на поверхности субстрата. Cell-substrate adhesion is a key factor affecting the cell functionality and fate. Therefore, for adequate biomodeling of cellular structures in vitro, it is necessary to carefully select the materials used. In this study, we evaluated adhesion of endothelial-like cells EA.hy926 to polymeric materials and glass, which are used in microfluidics to model blood vessels. It was shown that different types of polydimethylsiloxane (PDMS) provided low cell adhesion compared to glass and specially prepared polystyrene (PS). The treatment with oxygen plasma did not exert a significant effect on adhesion. Covering with collagen I, on the contrary, significantly improved adhesion. The protein gel quite well covered both the hydrophilic surface of the glass and the hydrophobic surface of the polymer. The features of individual cells spreading on the substrate surface were also studied using scanning probe microscopy.

Synthesis of Polystyrene Particles with Precisely Controlled Degree of Concaveness.

Shape is an essential property of polymeric particles. Herein, we propose a simple method to synthesize polymeric particles with a well-controlled concave shape. Our method takes advantage of the powerful seeded emulsion polymerization strategy with the well-known principle of “like dissolves like” in solvent chemistry. We first prepared polystyrene (PS) particles with a single dimple by seeded emulsion polymerization. Then the dimpled PS particles were dispersed in a dimethylformamide (DMF) and water mixture. Consequently, the non-crosslinked polymer chains inside the particle were dissolved by DMF, a good solvent for PS, and the PS chains migrated out of the particle, causing buckling of the dimple and enlargement of the concave. By systematic change of the fraction of DMF in the solvent mixture, we changed the amount of the dissolved PS chains, and achieved polymeric particles with precisely tuned degree of concaveness. These concave particles were found to readily self-assemble, driven by polymer-induced depletion interaction. The concave PS particles reported here provide potential building blocks for self-assembled polymeric materials, and new model systems for condensed matter research.

Hollow ZnO/Zn2SiO4/SiO2 sub-microspheres with mesoporous shells: Synthesis, characterization, adsorption and photoluminescence

The multifunctional versatile ZnO/Zn2SiO4/SiO2 hollow microspheres with porous structures on the shells are successfully fabricated by the sequential deposition of amino-functionalized SiO2 and then ZnO layers on the prepared polystyrene (PS) colloidal templates, and the subsequent calcination process. The formation of hollow morphology was confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Nitrogen sorption measurements also verify the presence of the mesoporous structure scattered on the shells. The application of the absorption capacity to remove toxic metal ions in water is performed. Furthermore, the photoluminescence (PL) results indicate that hollow composites prepared in our experiment have excellent optical properties. The origin of various PL bands is discussed as well. The high surface areas, together with void interiors and mesoporous walls make composites an efficient adsorbent and promising platform for optoelectronics and nanomedicine applications.

Enhanced Performance of Asymmetric Polystyrene Membrane by Incorporation of Pluronic F127 and Its Application for Pervaporation Separation

Pervaporation is an efficient membrane process for liquid separation. The past decades had witnessed substantial progress and exciting breakthroughs in both the fundamental and application aspect of pervaporation. In the present study, the separation of aqueous alcohol solution through wet-phase inversion prepared polystyrene (PS) membrane was investigated by using the pervaporation process. The role played by Pluronic F127 as nonionic surfactant in the formation of PS membrane was also studied. Addition of surfactant in the casting solution can suppress macrovoids in polymeric membrane. The formation of asymmetric PS membranes was discussed in terms of the presence of surfactant in the casting solution and the PS concentration. The surface properties of the asymmetric PS membranes were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The effects of polymer concentration, surfactant content, feed composition, and feed solution temperature on the pervaporation performance were evaluated. The separation factor towards water and the permeation rate for a 10 wt% aqueous ethanol solution through the asymmetric PS membrane with a 1.5 wt% Pluronic F127 was 39 and 140 g/m2 h.

High Hepatic Function Was Maintained on Electrospun Nanofibrous Scaffold

In this study, we prepared polystyrene (PS) nanofibers as hepatocytes culture substrates by electrospinning method and subsequently coated with specific ligand (poly(N--vinylbenzyl-- β-D-galactopyranosyl-(14)-D-gluconamide)(PVLA) for hepatocytes attachment. Rat hepatocytes’ behavior on the PVLA-coated and non-coated PS nanofibrous matrices have been investigated. Electrospun PS fiber structures revealed randomly aligned fibers with average diameter of 500 nm. Fabricated PS nanofibers had no bonding points like cotton fibers. Analyses by ATR/FTIR and ESCA revealed that PVLA was successfully coated to the surfaces of PS nanofibers. More hepatocytes were attached on the surface of PS nanofibers coated with PVLA than that on noncoated PS nanofibers. PS nanofibrous matrix could incorporate many cells into the interior of the matrix probably due to the suitable pore size. Cell viabilities cultured on PVLA-coated PS nanofibrous mats were maintained for 2 weeks, while it was decreased rapidly on PVLA-coated PS dishes. High hepatic function especially albumin secretion was maintained for 2 weeks on nanofibrous mats but rapidly decreased on flat PS dishes. These results indicate that nanofibrous structure enabled spheroid-like culture results in providing cell-cell communication and subsequent long-term maintenance of specific cell function.

Polystyrene nanocomposite materials: Preparation, morphology, and mechanical, electrical, and thermal properties

AbstractIn this study, we prepared polystyrene (PS) resin nanocomposites with antistatic properties by melt‐blending PS with nanoscale zinc oxide (ZnO). The effects of nanoscale ZnO on the electrical and physical characteristics of the PS nanocomposites were investigated. Two kinds of nanoscale powders, spherical zinc oxide (s‐ZnO) and zinc oxide whisker (w‐ZnO), were selected. The coupling agents vinyltriethoxysilane (VTES) and phenyltriethoxysilane (PTES) were used to improve the compatibility between the nanopowders and PS resin. The addition of s‐ZnO and w‐ZnO improved the antistatic characteristics of the materials. The surface resistivities of the s‐ZnO and w‐ZnO nanocomposites were significantly reduced by modification with VTES and PTES. The addition of ZnO nanopowder increased the flexural modulus and reduced the flexural strength. The silane coupling agents improved the flexural properties of the nanocomposites. The glass‐transition temperatures and thermal degradation temperatures of the ZnO/PS nanocomposites increased with ZnO content. Treatment with silane increased the glass‐transition temperatures and thermal degradation temperatures of the composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2266–2273, 2005