Preparation of ultrafine metal particle-supported fine carbon particles

Ultrafine metal particle-supported carbon particles were synthesized by pyrolysis of polymer particle–metal ions such as Co(II), Ni(II), Cu(II), Ag, Pd(II), and Rh(III) complexes. The sizes of metal particles increased with increasing pyrolysis temperature. Pd and Rh particles were on the whole smaller than were Co, Ni, and Cu, even though the amounts of Pd and Rh ions immobilized were higher. Rh particles supported on carbon particles exhibited high catalytic activity for the decomposition of hydrogen peroxide. © 1996 John Wiley & Sons, Inc.     

Polymer–metal composite particles: Metal particles on poly(St‐co‐MAA) microspheres

Poly(styrene‐co‐methacrylic acid) P(St‐co‐MAA) microspheres with a monodisperse size distribution were prepared by emulsifier‐free emulsion copolymerization of St and MAA. The effects of MAA content on the polymerization rate and the content of MAA in the copolymer were investigated by gravimetrical and IR methods, respectively. The results of XPS measurement indicated the presence of a carboxyl functional group. By chemical metal deposition, nickel or palladium particles were formed and deposited on the surface of P(St‐co‐MAA) microspheres to form P(St‐co‐MAA)Ni or P(St‐co‐MAA)Pd composite particles. XRD measurement and TEM observation confirmed that nickel and palladium metal particles in a small size (20–40 nm) were distributed on surface of the copolymer microspheres. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1693–1698, 2000     

Synthesis of monodisperse nonporous crosslinked poly(glycidyl methacrylate) particles with metal affinity ligands for protein adsorption

Monodisperse nonporous crosslinked poly(glycidyl methacrylate) (PGMA) particles with immobilized metal affinity ligands were prepared for selective recovery of proteins. The PGMA particles, with an average size of 2.2 µm, were prepared by a simple dispersion polymerization of glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA). The particles were characterized by scanning electron microscopy (SEM) and Fourier‐transform infrared spectroscopy (FTIR). The epoxy groups of the particles were modified with the metal chelating agent iminodiacetic acid (IDA), which forms metal–IDA chelates at the active sites. After charging with copper ions, the particles were used to recover a model protein, bovine hemoglobin (BHb), in a batchwise manner. The particles had the adsorption capacity of 218.7 mg g⁻¹ with little nonspecific adsorption. The adsorption behavior could be described with the Langmuir equation. The effect of pH on the adsorption was also studied. Regeneration of the metal‐chelated particles was easily performed with 50 mmol L⁻¹ ethylenediaminetetraacetic acid (EDTA), followed by washing with water and reloading with Cu²⁺. The particles could be very useful as an affinity separation adsorbent. Copyright © 2005 Society of Chemical Industry     

Surface properties and flocculations of globulin-immobilized fine polymer particles

Characteristics of globulin-immobilized styrene/acrylamide/acrylic acid copolymer [poly(St/AAm/AA)] fine particles and their flocculation by an antigen–antibody reaction were investigated as a function of acrylamide (AAm) content. Immobilization of globulin was carried out through octamethylenediamine with a carbodiimide reaction. The increase in AAm content in particles decreases the amounts of bovine γ-globulin (BγG) immobilized, shifts the isoelectric points of BγG-immobilized poly(St/AAm/AA) particles to acidic pH, and increases the dispersion stability of BγG-immobilized poly(St/AAm/AA) particles. The flocculation rates of antihuman epidermal growth factor (hEGF) immunoglobulin (IgG)-immobilized poly(St/AAm/AA) fine particles of low AAm content by the antigen-antibody reaction are higher than that of anti-hEGF IgG-adsorbed polystyrene particles, whereas those of high AAm content are lower and decreased with increasing AAm content. © 1994 John Wiley & Sons, Inc.     

An investigation of engineering parameters for the use of immobilized biomass particles in biosorption

Immobilized, inactive mycelia of Rhizopus arrhizus are preferential to native biomass for use in the biosorption of metal ions. Refinement of a proprietary immobilization technique previously developed at McMaster University enabled production of particles of immobilized Rhizopus arrhizus biomass having a 12–23% wt of polymer additive. The effects of production stage parameters on the intrinsic uptake capacity of the immobilized biomass were examined. Kinetic experiments showed the following trends: a decrease in the weight percent of the added polymer leads to an increase in the apparent uranium uptake capacity of the immobilized biomass particles far a given contact time. A decrease in the particle size improved the kinetics of metal uptake and led to an increase in the apparent uranium uptake capacity for the same contact time. An increase in the initial concentration of the uranium solution caused equilibrium conditions to be attained faster.     

Considerations on detailed analysis and particle growth in high impact polypropylene particles

Detailed analysis of the dispersion of ethylene and propylene copolymer components in high‐impact polypropylene particles was performed by the morphological observation, pore volume analysis, and microscopic Fourier transform infrared spectroscopy of SPring‐8. The results of the morphological observation and pore volume distribution suggest that copolymer components were formed in particles in such a manner as to fill the gaps of fine homopolypropylene particles. The results of the analysis by microscopic Fourier transform infrared spectroscopy were that the distribution of the amount of ethylene in the particles was homogeneous and indicated that copolymer components were dispersed uniformly within the particles. Moreover, spots with high amounts of ethylene were formed on the particle surface, and when voids existed within the particle, spots with high amounts of ethylene were also formed on the void surface. The structure of the copolymer components existing locally on the surface was practically similar to the structure of the copolymer components within the particles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of manganese, nickel and cobalt ferrites submicron particles in sulfonated crosslinked networks

Magnetic submicron particles of MnFe₂O₄, NiFe₂O₄ or CoFe₂O₄ were created in or around the porous sulfonated beads based on poly(styrene-co-divinylbenzene) using an in situ inorganic precipitation procedure. The copolymer beads were treated with a mixed iron/cobalt chloride electrolyte and the doped copolymer networks were converted to their oxides by reaction with sodium hydroxide and potassium nitrate in aqueous solution. Energy dispersive X-ray spectroscopy (EDS) coupled to scanning electron microscopy (SEM) allowed the observation of the presence of submicron particles in the 0.1-0.5 μm size range, which chemical microanalysis of emitted X-rays revealed the presence of metal oxide particle, such as nickel, manganese or cobalt iron oxide. The morphological features of the binary material particles have depended on the ferrite type. All beads have presented dispersed and agglomerated submicron particles of ferrite located on their surface and inner part as well. Magnetization data of the microbeads showed good ferromagnetic behavior.     

Separate or simultaneous immobilization of glucose oxidase and peroxidase on latex particles and their function

Glucose oxidase and peroxidase were immobilized individually or simultaneously on aminated latex particles by using sodium meta-periodide and borohydride. The amount of immobilized enzymes and their activity depended on the surface potential of particles and the surface density of their own, respectively. In the simultaneous immobilization of two enzymes, the predominant immobilization of peroxidase is attributed to higher carbohydrate content in peroxidase compared with that in glucose oxidase. Simultaneously immobilized enzymes worked better in the determination of glucose than the mixture of separately immobilized ones because of the close proximity of the two enzymes.     

Sieving of aerosol particles with metal screens

Metal screens with uniform micrometer-sized opening were employed to sieve aerosol particles by suppressing the adhesion of particles smaller than the openings. The collection efficiencies of monodispersed polystyrene latex (PSL) particles were experimentally determined using the metal screens with 1.2, 1.8, 2.5, and 4.2 μm openings at various filtration velocities. The particles smaller than the mesh opening adhered on the metal screen at a low filtration velocity, but the bounce-off of particles on the mesh surface suppressed the adhesion at a high velocity. As a result, we found that the adhesion of PSL particles larger than 0.3 μm mostly suppressed at a filtration velocity higher than 10 m s^?1 and therefore we can sieve aerosol particles according to the opening size of metal screens. We also found that the particle number concentration could be determined by measuring the increase in pressure drop since the clogging of metal screen openings takes place by the individual particles.

© 2016 American Association for Aerosol Research     

Immobilization of Pycnoporus sanguineus laccase by metal affinity adsorption on magnetic chelator particles

BACKGROUND: Immobilized enzymes provide many advantages over free enzymes including repeated or continuous reuse, easy separation of the product from reaction media, easy recovery of the enzyme, and improvement in enzyme stability. In order to improve catalytic activity of laccase and increase its industrial application, there is great interest in developing novel technologies on laccase immobilization. RESULTS: Magnetic Cu²⁺‐chelated particles, prepared by cerium‐initiated graft polymerization of tentacle‐type polymer chains with iminodiacetic acid (IDA) as chelating ligand, were employed for Pycnoporus sanguineus laccase immobilization. The particles showed an obvious high adsorption capacity of laccase (94.1 mg g^?1 support) with an activity recovery of 68.0% after immobilization. The laccase exhibited improved stability in reaction conditions over a broad temperature range between 45 °C and 70 °C and an optimal pH value of 3.0 after being adsorbed on the magnetic metal‐chelated particles. The value of the Michaelis constant (K_m) of the immobilized laccase (1.597 mmol L^?1) was higher than that of the free one (0.761 mmol L^?1), whereas the maximum velocity (V_max) was lower for the adsorbed laccase. Storage stability and temperature endurance of the immobilized laccase were found to increase greatly, and the immobilized laccase retained 87.8% of its initial activity after 10 successive batch reactions. CONCLUSION: The immobilized laccase not only can be operated magnetically, but also exhibits remarkably improved catalytic capacity and stability properties for various parameters, such as pH, temperature, reuse, and storage time, which can provide economic advantages for large‐scale biotechnological applications of laccase. Copyright © 2007 Society of Chemical Industry     

Swelling behavior of thermosensitive N-isopropylacrylamide–ethyl N-acryloylglycine submicron-sized copolymer gel particles

Submicron-sized N-isopropylacrylamide (NIPA)–ethyl N-acryloylglycine (ENAG) copolymer gel particles with various compositions were prepared by precipitation polymerization in water. Their swelling behaviors were determined by photon correlation spectroscopy (PCS). Our results showed that the volume transition temperature of copolymer gel particles decreased with increasing the mole ratio of ENAG. In model development, we modified the extended Flory–Huggins theory as a free energy of mixing term and employed the modified Flory–Rehner theory for the elastic contribution and compared the proposed model with our swelling data. The model predicted fairly well the swelling behaviors of copolymer gel particles. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 799–806, 1998     

Nanostructured latex particles synthesized by nitroxide-mediated controlled/living free-radical polymerization in emulsion

Suspensions of diblock and triblock copolymer particles comprising a poly(n-butyl acrylate) first/central block and polystyrene or poly(methyl methacrylate) second/outer blocks were synthesized by nitroxide-mediated controlled/living free-radical emulsion polymerization. Monofunctional and difunctional alkoxyamines based on the nitroxide SG1 were used as initiators. For the sake of simplicity, sequential monomer additions were performed without any removal of unreacted monomer. Self-assembly of the obtained block copolymers was investigated both under the latex form as well as after different thermal treatments. AFM and TEM analyses revealed the occurrence of “onion-like” lamellar microphases directly inside latex particles for high enough copolymer molar masses and irrespective of molar mass distribution. This particular organization evolved towards more classical block copolymer morphologies upon solvent casting and/or thermal annealing of latex films.     

Silicone-polyacrylate composite latex particles. Particles formation and film properties

Composite latex particles with a polydimethylsiloxane PDMS core and a poly(methyl methacrylate-co-n-butyl acrylate) P(MMA-BA) copolymer shell were synthesized by seeded emulsion polymerization using the PDMS latex as the seed. The compatibility between the two polymer phases was changed by introducing vinyl groups in the latex core. Monomer conversions and particle size evolution were monitored to see the influence of the nature of the core functionality on the polymerization kinetics and on the extent of secondary nucleation. Particle morphology was characterized by cryo-transmission electron microscopy. The P(MMA-BA) copolymer formed a regular shell around the PDMS seed, whereas nonuniform coatings were formed when vinyl functionalities were introduced into the seed. Films were produced from the latexes, and their surface property was analyzed by X-ray photoelectron spectroscopy and contact angle measurements. It was shown that the PDMS component segregated to the polymer/air interface and that the extent of segregation depended on the original particles structure. Because PDMS has a very low glass transition temperature, it can easily diffuse throughout the film material. However, protected by an acrylic shell, polymer diffusion is significantly hindered and the film then displays all the characteristic properties of the acrylic copolymer. The surface composition of the films formed by the structured particles which PDMS core was not totally covered by the polyacrylate, was found to be intermediate between the composition of the films issued from the core-shell latexes and that of the films produced from blends of pure polyacrylate and PDMS latexes.     

Synthesis and property behavior of dioctyl phthalate plasticized styrene–acrylate particles by Shirasu porous glass emulsification and subsequent suspension copolymerization

Two‐phase model styrene–acrylate copolymers were synthesized with a soft phase consisting of methyl acrylate, butyl acrylate, and butyl methacrylate. Besides the styrenic copolymers, copolymers containing a hard phase of methyl methacylate and methyl acrylate were also synthesized. Comonomer droplets with a narrow size distribution and fair uniformity were prepared using an SPG (Shirasu porous glass) membrane having pore size of 0.90 μm. After the single‐step SPG emulsion, the emulsion droplets were composed mainly of monomers, hydrophobic additives, and an oil‐soluble initiator, suspended in the aqueous phase containing a stabilizer and inhibitor. These were then transferred to a reactor, and subsequent suspension polymerization was carried out. Uniform copolymer particles with a mean diameter ranging from 3 to 7 μm, depending on the recipe, with a narrow particle size distribution and a coefficient of variation of about 10% were achieved. Based on the glass‐transition temperatures, as measured by differential scanning calorimetry, the resulting copolymer particles containing a soft phase of acrylate were better compatibilized with a hard phase of methyl methacrylate than with styrene with dioctyl phthalate (DOP) addition. Glass‐transition temperatures of poly(MMA‐co‐MA) particles were strongly affected by the composition drift in the copolymer caused by their substantial difference in reactivity ratios. Incorporation of DOP in the copolymer particles does not significantly affect the glass‐transition temperature of MMA‐ or MA‐containing copolymer particles, but it does affect the St‐containing copolymer and particle morphology of the copolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3037–3050, 2003     

Immobilization of glucoamylase on magnetic poly(styrene) particles

Magnetic poly(styrene) particles including active groups were prepared for enzyme immobilization without any activation process. Glucoamylase, which is widely used in industry, was immobilized onto these particles. The effects of pH, buffer concentration, and temperature on immobilization were investigated; moreover, the effect of immobilization temperature on immobilized glucoamylase activity was determined for the hydrolysis of maltose. The acetate buffer with the concentration of 6 × 10⁻⁴ M at pH 4 and 20–30°C was found as the most suitable medium for the immobilization of the glucoamylase. The amount of bound protein is 8 mg/g particle with the immobilization yield of 70%. The maximum activity obtained with immobilized glucoamylase is approximately 70% of the free one. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 69–73, 1999     

Preparation of fine polymer particles containing metallocene derivatives

This article deals with preparations of fine particles of metallocene copolymers by emulsifierfree emulsion polymerization of vinylferrocene (VFc), ferrocenylmethyl methacrylate (FMMA), 1-ferrocenylethyl methacrylate (1-FEMA), 2-ferrocenylethyl methacrylate (2-FEMA), and 1-ruthenocenylethyl methacrylate (1-REMA) with acrylonitrile (AN), styrene (St), and methyl methacrylate (MMA) in water/ethanol medium. As a result, spherical copolymer particles containing metallocene derivatives have been successfully synthesized in the particle size of ca. 120 to 600 nm. The contents of ferrocenyl or ruthenocenyl groups in copolymer particles increased with increasing concentration of charged metallocene derivatives, while the amounts of metallocene derivatives incorporated into particles are much lower than the charged ratio. © 1994 John Wiley & Sons, Inc.     

Branched methyl methacrylate copolymer particles prepared by RAFT dispersion polymerization

Reversible addition–fragmentation chain transfer (RAFT) dispersion copolymerization of methyl methacrylate (MMA) and tripropylene glycol diacrylate (TPGDA) was carried out in ethanol/water in the present work. S-1-Dodecyl-S′-(α,α-dimethyl-α″-aceticacid) trithiocarbonate (TTC) was used as a chain transfer agent to inhibit the occurrence of gelation. Branched poly(methyl methacrylate) (PMMA) particles with a very narrow size distribution was prepared by a two-stage method: the addition of a RAFT agent and a TPGDA agent to the system followed the nucleation stage. The particles had an average diameter within 1.9–2.7 μm and size distribution of 1.12–1.24. Molecular weight, molecular weight distribution, compositions and structure of copolymer were investigated by GPC and 1H NMR characterization. The GPC curves showed a bimodal distribution, indicating that MMA homopolymer was synthesised during the nucleation stage. In addition, 1H-NMR proved that MMA and TPGDA branched copolymer was synthesised after the nucleation stage. TPGDA fraction in the copolymer was lower than that in the initial monomer. It was determined that the intrinsic viscosity of the copolymer decreased with conversion and the Mark–Houwink exponent α of copolymer was reduced from 0.643 to 0.548, which further confirmed the branched structure of the copolymer.     

聚氨酯-丙烯酸酯树脂颗粒的研究

制备了丙烯酸羟乙酯（HEA）封端的聚氨酯大分子单体（PUA）,并采用悬浮聚合法合成了一系列聚氨酯-丙烯酸酯树脂颗粒,分析了分散剂用量及种类对颗粒大小的影响;热重分析表明聚氨酯-聚甲基丙烯酸乙酯（PUA-PEMA）树脂的起始分解温度为230.5℃;采用SEM表征了树脂的表面形貌;溶胀性能测试表明PUA-PEMA和聚氨酯-苯乙烯（PUA/PSt）2种树脂对甲苯均有良好的吸附性能,在5 min时的吸附率分别达到了3.38 g/g和4.28 g/g,PUA-PSt树脂对有毒单体甲苯和氯仿的溶胀率为255%和330%。     

Preparation of block copolymer particles by two-step atom transfer radical polymerization in aqueous media and its unique morphology

Submicron-sized poly(i-butyl methacrylate)-block-polystyrene particles were successfully prepared by two-step atom transfer radical polymerization (ATRP) in aqueous media: ATRP in miniemulsion (miniemulsion-ATRP) followed by ATRP in seeded emulsion polymerization (seeded-ATRP). When PiBMA particles, which were prepared by the miniemulsion-ATRP process with polyoxyethylene sorbitan monooleate (Tween 80, nonionic emulsifier) of 6-10 wt % based on iBMA, were used as seed in the seeded-ATRP of styrene, the block copolymer particles having narrow molecular weight distribution and pre-determined molecular weight were prepared at high conversion. Some block copolymer particles had an ‘onion-like’ multilayered structure. In this way, controlled/living free radical polymerization can be employed to obtain unique particle morphologies that may not be easily accessible using conventional free radical polymerization.     

Polymeric particles prepared with fluorinated surfmer

Fluoro-containing particles have been obtained by miniemulsion polymerization of styrene and n-butyl methacrylate in presence of fluorinated monomer mono-fluoroalkyl maleate (MFM) which acts as a surfmer providing efficient stability to obtained dispersion and functionalization of particle surface with fluoro-groups. Increase of the MFM concentration in reaction mixture reduces the particle size and dispersions with narrower particle size distribution can be obtained. Blends of fluorinated latexes with styrene-butadiene copolymer latex were examined with regard to formation of low free energy surfaces. It has been shown that blends containing MFM-functionalized polymeric particles possess more hydrophobic surfaces then similar latex films, where particles prepared by polymerization of expensive fluorinated monomer have been applied.