Novel Hybrids of Polystyrene Nanoparticles and Silica Nanoparticles-Grafted-Graphite Via Modified Technique

We have designed polystyrene nanoparticles through modified nanoprecipitation cosolvent evaporation technique and conventional nanoprecipitation and solvent evaporation. Polystyrene nanoparticles were embedded with silica nanoparticles and graphite to analyze scope of nanoprecipitation cosolvent evaporation. Ultraviolet–visible spectroscopic revealed decreased band gap of polystyrene nanoparticles obtained via nanoprecipitation cosolvent evaporation. Scanning electron microscopic showed uniform morphology of polystyrene nanoparticles and polystyrene nanoparticles-based nanocomposites engendered by nanoprecipitation cosolvent evaporation. X-ray diffraction disclosed presence of crystalline domains due to silica nanoparticles content in amorphous structure. Glass transition temperature was increased from 94 (polystyrene) to 124°C (PSNPs/SiNPs 0.6) and 137°C (PSNPs/SiNPs/G 0.6) with filler loading. Electrical conductivity of PSNPs/SiNPs/G 0.6 was also found to be higher (1.53 S/cm).     

Preparation of polymeric nanoparticles by novel electrospray nanoprecipitation

Polymeric nanoparticles have important applications in drug delivery, biotechnology, diagnostics and energy harvesting. We report a new technique named electrospray nanoprecipitation, which combines electrospray with agitated solvent displacement. The process enables one‐step formation of polymeric nanoparticles <100 nm in size that are near‐monodisperse with a diameter range significantly lower than could be obtained using either electrospray or agitated solvent displacement technique alone. Both reduction of polymer solution concentration and the addition of poly(vinyl alcohol) emulsifier in the water–non‐solvent medium further reduce the average particle diameter. The technique provides an effective and straightforward method to further reduce the size range of near‐monodisperse nanoparticles achievable in a single step, which can be readily adapted for reducing the achievable size range of core–shell structures using popular one‐step encapsulation techniques such as coaxial electrospray. © 2014 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Nanofibers from recycle waste expanded polystyrene using natural solvent

Summary A new recycling technique has been developed. In this method, EPS (expanded polystyrene), generally called Styrofoam, is dissolved with natural solvent, d-limonene and electrospun. This method can economically produce the nanofibers. The electrospinning process produces a nonwoven mat of long polymer fibers with diameters in the range of 10–500 nm and high surface areas per unit mass. PS (Polystyrene) polymer dissolved in different solvents such as THF (Tetrahydrofuran), DMF (Dimethylformaide), and DMAc (Dimethylacetamide) etc. may all be electrospun into nanofibers. These solvents cause environmental problem and difficulty of process handling. Natural solvent, d-limonene is used for dissolving PS. PS nanofibers are produced with PS solution using d-Limonene. This paper describes the use of polystyrene (PS) nanofibers electrospun from recycled EPS solution dissolved in d-limonene. The electrospun polystyrene nanofiber diameters vary from 300 to 900 nm, with an average diameter of about 700 nm.     

The conditions of cationic exchange with the use of recycling polystyrene derivative,the product of sulfonation by silica sulfuric acid

Growing amount of waste plastics has become an environmental problem on a global scale. This study presents an investigation of the conditions of cleaning water from heavy metal ions using chemically recycled polystyrene. To get effective ion exchangers, the sulfonation of virgin polystyrene and expanded polystyrene wastes were obtained using silica sulfuric acid. As it turned out, the use of this solid sulfonating agent simplifies the separation of the polymeric product from the acid and the solvent in comparison to conventional sulfonation methods. The ion exchange behavior of copper and zinc cations in the yielded sulfonated derivatives of polystyrene was studied. Batch shaking adsorption experiments depending on contact time, pH, temperature, and dosage of adsorbate were carried out. The stability of resin to cyclical adsorption and regeneration (column experiment) was also investigated. We report that resins have a high adsorption efficiency with total ion exchange capacity (IEC) about 2.6 meq g^?1, which drops with decreasing pH owing to competition between protons H⁺ and metal cations, whereas with the increasing resin doses the removal of cations rises for a constant initial metal concentration. The speed of cation exchange for yielded adsorbents was even better than for commercial resins. After 360 cyclical adsorption and regeneration in column, resin had working IEC of about 2.3 meq g^?1. The study shows that cation exchange resin from polystyrene wastes can be used as an efficient adsorbent for the removal of heavy metal ions from water. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Particle size and distribution of biodegradable poly‐D,L‐lactide‐co‐poly(ethylene glycol) block polymer nanoparticles prepared by nanoprecipitation

A biodegradable block copolymer, poly‐D ,L ‐lactide (PLA)‐co‐poly(ethylene glycol) (PEG), was prepared by the ring‐opening polymerization of lactide with stannous caprylate [Sn(Oct₂)] as a catalyst; then, the PLA–PEG copolymer was made into nanoparticles by nanoprecipitation under different conditions. The average molecular weight and structure of PLA–PEG were detected by ¹H‐NMR and gel permeation chromatography. The sizes and distributions of the nanoparticles were investigated with a laser particle‐size analyzer. The morphologies of the nanoparticles were examined by transmission electron microscopy. The effects of the solvent–nonsolvent system, operation conditions, and dosage of span‐80 on the sizes and distributions of the nanoparticles are discussed. The results show that acetone–water was a suitable solvent–nonsolvent system and the volume ratio of the nonsolvent phase to the solvent phase (O/W) (v/v), the concentration of PLA–PEG in the solvent phase, and the dosage of span‐80 had important effects on the particle sizes and distributions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1884–1890, 2005     

Development of biodegradable polymeric nanoparticles for encapsulation,delivery, and improved antifungal performance of natamycin

The aim of this study was to evaluate biodegradable poly(lactide‐co‐glycolide) nanoparticles as potential nano‐delivery systems for the food antifungal compound natamycin. Natamycin‐loaded nanoparticles were prepared at various ratios polymer/antifungal by the nanoprecipitation technique, resulting in nano‐size particles (80–120 nm) with a narrow distribution and a spherical morphology. Complexation of natamycin with PLGA and active participation to the nanoparticle formation were evidenced by a mean diameter reduction of 10–30 nm, although encapsulation levels remained low due to the zwitterionic and partially hydrophilic nature of natamycin. Physical state analyses highlighted the presence of natamycin in an amorphous or molecularly dispersed state within the polymeric matrix. This translates into high availability of free antifungal molecules reflected in burst release and fast in vitro release kinetics rates as well as enhanced antifungal performance against the model food yeast Saccharomyces cerevisiae, offering a potential benefit for antifungal protection compared with the commercially available natamycin products. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43736.     

Shape control synthesis of polymeric hybrid nanoparticles via surface‐initiated atom‐transfer radical polymerization

Polymeric hybrid nanoparticles were synthesized via surface‐initiated atom‐transfer radical polymerization (SI‐ATRP) method on the surface of gold nanoparticles in cyclohexanone. Tetraoctyl ammonium bromide (TOAB) as a phase transfer agent was used to transfer the gold nanoparticles into cyclohexanone, which will be replaced by disulfide initiator on the surface of gold nanoparticles. Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV–vis spectroscopy were utilized to characterize the product to make sure the experiment had been conducted. The results showed that the polymeric gold hybrid nanoparticles with different structures could be controlled by adjusting the ratio of initiator and gold nanoparticles in ATRP. If the ratio is very little, asymmetric polystyrene–gold hybrid nanoparticles were synthesized, and a single gold nanoparticle was attached with a polystyrene sphere. If the ratio becomes larger, core–shell polystyrene–gold nanocomposite particles were obtained resulting in gold nanoparticle encapsulated by a uniform polymer shell. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43584.     

Flow-based reactor design for the continuous production of polymeric nanoparticles

Polymeric nanoparticles (NPs) are versatile and effective drug delivery systems (DDS) that can be produced via nanoprecipitation of block copolymers. Yet, translation into clinical products has been limited. Thus, methods for NP production that enable rapid formulation screening and continuous production are needed. Toward this end, we engineered a coaxial jet mixer (CJM) for controlled and continuous nanoprecipitation in flow. The CJM enabled continuous assembly of poly(ethylene glycol)-block-polylactide NPs with various co-solvents and was compared to batch nanoprecipitation. Other fabricated microfluidic devices were suitable for small scale formulation screening but more limited in scalable and continuous processes. In contrast, the CJM was tolerant to all water-miscible solvents tested, enabled formulation screening, and scalable production of NPs and DDS. In total, the CJM provides a complementary approach to the process engineering of polymeric NP formation that can be used broadly for formulation screening and production.     

Synthesis of ultrastable eu‐complex/polystyrene composite luminescent nanoparticles using a solvent swelling method

Nanoparticles composed of Eu‐complex, Eu(TTA)₃Phen, and polystyrene (PS) were successfully synthesized through an improved solvent swelling method. The unstable Eu(TTA)₃Phen could be protected by the hydrophobic shell of PS nanoparticles. This method is very appropriate to embed unstable luminescent molecules into polymer nanoparticles. The as‐synthesized luminescent PS nanoparticles have been turned out to be water‐dispersible, strong red luminescent, ultrastable in strong acid and alkali, and luminescence lifetime enhanced. A cell imaging assay was further carried out and strong luminescent signal could be obtained, which showed that the as‐synthesized luminescent Eu‐complex/PS nanoparticles are a good candidate to be used as luminescent nanoparticles in tumor cell detection. This solvent swelling method is simple, easy to scale‐up, and has great potential in the preparation of other luminescent nanoparticles. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Nanoparticle popsicle: Transdermal delivery of nanoparticles using polymeric microneedle array

A number of nanoparticles are currently applied for medical or medicinal research fields through conjugating with drugs or bio-molecules such as DNA, RNA, and peptides. There are three distinct ways to deliver nanoparticles into animal and human bodies: injection, feeding, and transdermal administration. We fabricated a polymeric microneedle array carrying nanoparticles on the end-tip of needles for an efficient delivery of functional nanoparticles through the skin. The polymeric microneedles with a length ranging from 600 to 1,000 μm were casted out using laser-printed PDMS (polydimethylsiloxane) molds where the 50 nm silica or polystyrene nanoparticles had been filled by centrifugation. When the microneedle array was applied to the porcine cadaver skin, nanoparticles were quickly and stably dispersed in the hypodermis. Microneedle array conjugated with nanoparticles has a potential for an alternative method to deliver cosmetic or pharmaceutical materials into human skin locally without professional procedures.     

Recycled Polyolefin-Based Plastic Wastes for Sound Absorption

Recycling of high-volume polyolefin-based packaging wastes in India is challenging, as they have low recycle value, high levels of contamination, and lack of direct processing methods. This work discusses a two-stage mechanical processing method for recycling the polyolefin-based plastic wastes that are not conventionally recycled. With the objective of improving specific properties like sound absorption and noise reduction, inhomogeneities were introduced in the recycled product. This was achieved by mixing polyolefin-based packaging wastes with other waste materials such as plastic-coated aluminium foils, expanded polystyrene, and coir pith in varying quantities. More than 30 times volume reduction was achieved by a two-stage compression molding process. The sound absorption properties of the recycled materials are found to be comparable to expanded polystyrene and glass wool when small quantities (2–3 wt%) of materials like expanded polystyrene waste and coir pith were added. Impact strength of the recycled material decreased with increasing amounts of secondary additives like metal foils. Flexural strength of the recycled material was found to be maximum at about 30 wt% of metal foils. The end product could find applications in the construction industry due to the sound-absorption properties and the mechanical strength.     

Graft polymerization of styrene onto starch by simultaneous cobalt-60 irradiation

Starch-g-polystyrene copolymers have been prepared by the simultaneous ⁶⁰Co-irradiation of starch–styrene mixtures, and copolymers have been characterized with respect to weight per cent polystyrene (% add-on) and also the molecular weight and molecular weight distribution of polystyrene grafts. In a typical polymerization, 4 g each of starch and styrene were blended with 1 ml water and 1.5 ml of an organic solvent; the resulting semisolid paste was irradiated to a total dose of 1 Mrad. With ethylene glycol, acetonitrile, ethanol, methanol, acetone, and dimethylformamide as the organic solvent, values for % add-on ranged from 24% to 29%. The highest % add-on (43%) and the highest conversion of styrene to grafted polymer (76%) were obtained when the organic solvent was omitted, and water alone was used. When water was also omitted, polymerization of styrene was negligible; however, graft copolymer was formed in the absence of water when either ethylene glycol or ethanol was added. Attempts were unsuccessful to achieve a % add-on greater than 43% by doubling the amount of styrene in the polymerization recipe. Mixtures of equal weights of starch and styrene are relatively nonvicious, but these mixtures thicken when either water or ethylene glycol is blended in. Reasons for this thickening action and the possible influence of thickening on the graft polymerization reaction were explored.     

Synthesis of copper–polystyrene nanocomposite particles using water in supercritical carbon dioxide medium and its antimicrobial activity

Copper‐encapsulated polystyrene nanocomposite particles were prepared through ex situ dispersion of Cu nanoparticles into monomer droplets and subsequent polymerization using water in supercritical carbon dioxide (water‐in‐sc‐CO₂) at 70°C. First, colloidal dispersion of copper nanoparticles was synthesized by chemical reduction of copper chloride (CuCl₂) using sodium borohydrate (NaBH₄) as reducing agent. Colloidal dispersion of copper nanoparticles was added slowly during the polymerization of styrene using water‐in‐sc‐CO₂ medium at 70°C and 20.68 MPa. Cu nanoparticle encapsulated polymer particles were characterized by UV, X‐ray diffraction, thermogravimetric analysis, SEM, and TEM. Cu nanoparticles were uniformly distributed inside the polymer matrix during the polymerization process. This work represents a simple way to prepare a variety of metal nanoparticles encapsulated polymer particles using water‐in‐sc‐CO₂ medium. The Cu/polystyrene nanocomposite particles exhibit antimicrobial activity against a number of bacteria. The current work represents a simple, cheap and universal way to prepare a variety of metal–polymer nanocomposite materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of poly{[α‐maleic anhydride‐ω‐methoxy‐poly(ethylene glycol)]‐co‐(ethyl cyanoacrylate)} copolymer nanoparticles

Poly{[α‐maleic anhydride‐ω‐methoxy‐poly(ethylene glycol)]‐co‐(ethyl cyanoacrylate)} (PEGECA) copolymers were prepared by radical polymerization of macromolecular poly(ethylene glycol) monomers (PEGylated) and ethyl 2‐cyanoacrylate in solvent. The structures of the copolymer were characterized by Fourier‐transform infrared (FTIR) and proton nuclear magnetic resonance (¹H‐NMR). The morphology and size of the PEGECA nanoparticles prepared by nanoprecipitation techniques were investigated by transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS) methods. The results show that the PEGECA can self‐assemble into highly stable nanoparticles in aqueous media, and inner core and outer shell morphology. The size of the nanoparticles was strongly influenced by the solvent character and the copolymer concentration in the organic solvents. A hydrophobic drug, ibuprofen, was effectively incorporated into the nanoparticles, which provides a delivery system for ibuprofen and other hydrophobic compounds. Copyright © 2005 Society of Chemical Industry     

Morphology,structure, and properties of metal oxide/polymer nanocomposite electrospun mats

Adding nanoparticles into polymer solutions before electrospinning creates unique hierarchical morphologies dispersed throughout small diameter nanoparticle‐polymeric fibers. Effects of polymer composition, nanoparticle (NP) type, loading, and electrospinning voltage conditions were studied. As examples, indium, iron, and titanium oxide engineered nanoparticles (NPs) were dispersed into polyvinylpyrrolidone or polystyrene and electrospun. NP loadings below 5 wt % did not affect critical voltage required for Taylor cone formation, whereas higher NP loadings require higher critical voltages. Polymeric fiber thickness and macroscopic morphology is not impacted by up to 5 wt % NP loadings, and NP dispersion throughout the fibers were similar to their dispersion in initial polymer suspension. NP loadings above 5 wt % increased viscosity, which decrease subsequent fiber diameter. Experiments in water containing inorganic and organic pollutants in water demonstrate that the polymer is largely nonporous. This work enables design of multifunctional nanomaterial‐polymer composite fibers for wide‐ranging applications such as water and air treatment. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43811.     

A novel method to prepare magnetic polymer‐based anion exchangers and their application

Magnetic microspheres with ion‐exchange features were prepared by applying a swelling and penetration process using polystyrene–divinylbenzene‐based anion‐exchange resins as starting materials. The polymeric anion‐exchange particles were swollen with an aqueous solution of N‐methyl‐2‐pyrrolidone, followed by incubation with superparamagnetic iron oxide nanoparticles to allow them to penetrate into the swollen particles. The pH value in the solution of magnetic nanoparticles could significantly influence the uptake of magnetic nanoparticles by the swollen anion‐exchange particles. Higher amounts of magnetic nanoparticles entrapped within anion exchangers could be achieved at pH 10–12. An increase in the concentration of magnetic nanoparticles led to a higher density of magnetic nanoparticles entrapped within the interior of anion exchangers and, thus, higher magnetization of the magnetic anion exchangers. Loading of the magnetic nanoparticles onto the exchanger had no effect on anion‐exchange functionality. The utility of the resulting magnetic anion‐exchange resins was demonstrated for the isolation of plasmid pEGFP‐C1 from Escherichia coli cell lysates. The magnetic anion‐exchange microspheres could be easily collected within a few seconds in a magnetic field. Thus, automation of the protocol for DNA isolation using these magnetic anion‐exchange resins has a high potential. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40725.     

Water-assisted formation of honeycomb structured porous films

Honeycomb structured porous materials were formed using four different casting variations of the water droplet templating method. The film quality of the materials generated from these casting techniques (airflow, cold stage, casting on water, and emulsion methods) was investigated by altering the polymer architecture and composition. Linear, star, and comb polystyrene as well as an amphiphilic diblock copolymer comprised of polystyrene-block-poly(dimethylacrylamide) (PS-b-PDMA) were previously synthesized and cast into films via these techniques. While irregular pore distributions were observed for linear polystyrene films generated by every technique screened, increasing the architectural complexity of the polymer yielded more regular films for a broad range of casting conditions for each of the techniques. With the exception of linear polystyrene, the airflow casting technique was shown to be the only technique capable of generating regular porous films for all of the polymeric materials.     

Use of polyethyleneimine dendrimer as a novel graded-modulus interphase material in polymeric composites

The effectiveness of polyethyleneimine (PEi) dendrimer as a novel graded-modulus interphase material in polymeric composites is discussed in the context of core (polystyrene)–shell (PEi) nanoparticles affecting the mechanical properties of epoxy. The dendrimer is grafted onto the surface of polystyrene (PS) particles via a free radical polymerization reaction of styrene monomers in a non-aqueous polar solvent with t-butyl hydroperoxide (TBHP) as initiator and mild heating. The effects of both particle loading and core/shell composition are investigated. The mechanical test results in all cases show an increase in both stiffness and fracture toughness or the ability of the polymer to resist crack growth, as opposed to the commonly seen trade-off between these properties in previously studied soft particles. SEM micrographs suggest that the crosslinks with epoxy in the dendrimer network, leading to a dramatic interface stretching as the core-to-shell ratio decreases, and the capability of the dendrimer to 'harden' PS particles by diverting cracks through them are responsible for the enhancements.     

Microfabrication by X‐ray‐induced polymerization above the lower critical solution temperature

A polymer synthesis method is presented in which chain growth driven by exothermic reaction stimulates a gradual chain collapse. The globular precipitates in such systems can be restrained from coalescing by polymerizing in a quiescent environment. Time‐resolved small‐angle scattering study of the methacrylic acid polymerization kinetics in a quiescent system above its lower critical solution temperature (LCST) in water reveals the following features of this method: (a) growing oligomers remain as rigid chains until a critical chain length is reached, at which they undergo chain collapse, (b) radius of gyration increases linearly with time until a critical conversion is reached, and (c) radius of gyration remains constant after the critical conversion, even while conversion is gradually increasing. Following this self‐stabilizing growth mechanism, we show that nanoparticles can be directly synthesized by polymerizing N‐isopropylacrylamide above its LCST in water. The average size of nanoparticles obtained from a polymer–solvent system is expected to be the maximum extent of reaction spread at that monomer concentration. This hypothesis was then verified by polymerizing N‐isopropylacrylamide above their LCST in water, but by initiating the reaction with X‐rays shielded by a mask. The microfabricated patterns conform well to the size and shape of the mask used confirming that the growing chains do not propagate beyond the exposed regions as long as the reaction temperature is maintained above the LCST. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 429–425, 2006     

Synthesis and characterization of an amphiphilic pluronic‐poly(D,L‐lactide‐co‐glycolide) copolymer and their nanoparticles as protein delivery systems

A new amphiphilic Pluronic (F68)‐PLGA copolymer, which can be used to prepare the stealth or long‐circulating nanoparticles, was synthesized with Pluronic (F68), DL ‐Lactide, and glycolide. The structures of Pluronic (F68)‐PLGA copolymer as the products were characterized with infrared spectrometry, nuclear magnetic resonance and their molecular weights were determined by gel permeation chromatography. Two methods, double emulsion (DE) and nanoprecipitation (NP), were employed to fabricate the polymeric nanoparticles. Bovine serum albumin (BSA) was loaded into nanoparticles as a model protein. Influence of the preparation conditions on the nanoparticles size, encapsulation efficiency, and release profile in vitro was investigated. They showed the entrapment efficiency of 42.9–63.4% and the average diameter of 119.1–342.8 nm depending on the fabrication technique of nanoparticles and the type of copolymer. The stability maintenance of BSA in the nanoparticle release in vitro was also measured via sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE), circular dichroism (CD), and fluorescence spectrometry. The results showed that the new copolymer could load BSA effectively and BSA kept stable after it was released from the nanoparticles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008