Removal of Cr(VI) from aqueous solution using amino‐modified Fe3O4–SiO2–chitosan magnetic microspheres with high acid resistance and adsorption capacity

A novel, bioadsorbent material of polyethylenimine‐modified magnetic chitosan microspheres enwrapping magnetic silica nanoparticles (Fe₃O₄–SiO₂–CTS‐PEI) was prepared under relatively mild conditions. The characterization results indicated that the adsorbent exhibited high acid resistance and magnetic responsiveness. The Fe₃O₄ loss of the adsorbent was measured as 0.09% after immersion in pH 2.0 water for 24 h, and the saturated magnetization was 11.7 emu/g. The introduction of PEI obviously improved the adsorption capacity of Cr(VI) onto the adsorbent by approximately 2.5 times. The adsorption isotherms and kinetics preferably fit the Langmuir model and the pseudo‐second‐order model. The maximum adsorption capacity was determined as 236.4 mg/g at 25°C, which was much improved compared to other magnetic chitosan materials, and the equilibrium was reached within 60 to 120 min. The obtained thermodynamic parameters revealed the spontaneous and endothermic nature of the adsorption process. Furthermore, the Cr(VI)‐adsorbed adsorbent could be effectively regenerated using a 0.1 mol/L NaOH solution, and the adsorbent showed a good reusability. Due to the properties of good acid resistance, strong magnetic responsiveness, high adsorption capacity, and relatively rapid adsorption rate, the Fe₃O₄–SiO₂–CTS‐PEI microspheres have a potential use in Cr(VI) removal from acidic wastewater. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43078.     

High‐mechanical‐strength ferrohydrogels with a magnetically dispersed phase as multifunctional crosslinkers

In this article, we report a facile strategy for preparing high‐mechanical‐strength ferrohydrogels containing magnetic nanoparticles homodispersed by a thermodynamically stable Pickering emulsion (PE). After the monomers were mixed with the PE, including methacryloxy propyl trimethoxyl silane emulsified by ferric oxide (Fe₂O₃) nanoparticles as the dispersed phase, hydrogels were synthesized by free‐radical polymerization. In contrast to conventional hydrogels crosslinked by a molecular crosslinker, in our new approach, the magnetic PE particles served as individual, multifunctional crosslinkers. Characterizations of the swelling behavior, the mechanical properties, and other properties indicated that our ferrohydrogels exhibited outstanding physical performances that were superior to those of traditional hydrogels and magnetic responsiveness. These ferrohydrogels may have applications in soft and controllable actuators. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41950.     

Molecularly imprinted polymer microspheres derived from pickering emulsions polymerization in determination of di(2‐ethylhexyl) phthalate in bottled water samples

The mono‐dispersed macroporous Molecularly Imprinted microspheres (MIPMs) selective for Diethylhexyl Phthalate (DEHP) were synthesized by Pickering emulsion polymerization. Silica nanoparticles were stabilizers in forming a stable oil‐in‐water emulsion, while the polymeric system was prepared by radical polymerization using methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross‐linker. The results of scanning electron microscopy and nitrogen adsorption desorption measurement indicated that the obtained polymer microspheres had regularly porous structure and narrowly diameter distribution (100 nm), besides the specific surface area (S_BET) was 452 m² g^?1, pore volume was 9.685 cm³ g^?1, and pore diameter was 5.089 nm. The equilibrium adsorption capacity of MIPs was 1.75 mg g^?1 at 298 K. Good selectivity for DEHP in another two kinds of analogies (DBP and DAP) was demonstrated with high selectivity coefficients, respectively 17.753 and 19.450. In the end, DEHP‐MIP was used as packing of solid‐phase extraction to form an sensitive analytical method in extraction and enrichment DEHP in bottled water samples with the limits of detection of 1.7–2.5 μg L^?1.The recoveries at three spiking level (0.05, 0.1, and 1 mg L^?1) were varied between at 97.5 and 103.1% with RSD values below 3.5. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43484.     

Molecularly imprinted polymer prepared by Pickering emulsion polymerization for removal of acephate residues from contaminated waters

A molecularly imprinted polymer (MIP) prepared with Pickering emulsion polymerization was designed by a computational approach for removal of acephate from aqueous solution. Methacrylic acid, ethylene glycol dimethacrylate, and chloroform were screened as the optimal functional monomer, crosslinker, and porogen by the Gaussian 03 package using the density functional theory method. The polymerization was carried out in an oil‐in‐water emulsion using nano‐SiO₂ particles as stabilizer instead of a toxic surfactant. The characterization results indicated that the prepared MIP had a porous and hollow core, and the particle size was approximately 20 μm. The binding and recognition abilities of MIP for acephate were studied through equilibrium adsorption analysis and selectivity analysis. The results showed that the MIP had high binding capacity and excellent selectivity for acephate. The saturated binding amount could reach 6.59 × 10³ μg/g. The Langmuir isotherm model gave a good fit to the experimental data. Moreover, the results of a reusability analysis and practical application suggested that the prepared MIP provides the potential for removal of acephate residues from aqueous solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43126.     

Synthesis of poly(butyl acrylate‐co‐methyl methacrylate)/montmorillonite waterborne nanocomposite via semibatch emulsion polymerization

Poly(butyl acrylate‐co‐methyl methacrylate)‐montmorillonite (MMT) waterborne nanocomposites were successfully synthesized by semibatch emulsion polymerization. The syntheses of the nanocomposites were performed in presence of sodium montmorillonite (Na‐MMT) and organically modified montmorillonite (O‐MMT). O‐MMT was used directly after the modification of Na‐MMT with dimethyl dioctadecyl ammonium chloride. Both Na‐MMT and O‐MMT were sonified to obtain nanocomposites with 47 wt % solids and 3 wt % Na‐MMT or O‐MMT content. Average particle sizes of Na‐MMT nanocomposites were measured as 110–150 nm while O‐MMT nanocomposites were measured as 200–350 nm. Both Na‐MMT and O‐MMT increased thermal, mechanical, and barrier properties (water vapor and oxygen permeability) of the pristine copolymer explicitly. X‐ray diffraction and transmission electron microscope studies show that exfoliated morphology was obtained. The gloss values of O‐MMT nanocomposites were found to be higher than that of the pristine copolymer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42373.     

Core‐shell latex synthesized by emulsion polymerization using an alkali‐soluble resin as sole surfactant

A series of alkali‐soluble resins were prepared from esterification reaction of styrene‐maleic anhydride copolymer (SMA) and four fatty alcohols having different alkyl chains. The critical aggregates concentration of the prepared hemiester was lower than SMA, indicating that modification of SMA resin with long alkyl chains could improve their emulsification efficiency. The detailed experiments of emulsion polymerization of methyl methacrylate and butyl acrylate using these hemiesters as sole surfactants showed that SMA‐C12‐75, SMA‐C14‐70, and SMA‐C16‐65 were good surfactants. In the end, we successfully prepared stable latexes using above three good surfactants with relatively low surfactant concentration and high solid content. Characterization of latexes by Zetasizer and transmission electron microscopy revealed that particles of these latexes have core‐shell nanostructure with average particle size below 60 nm. Compared with SMA, the improvement of emulsification efficiency of its hemiesters may come from the better hydrophilic‐lipophilic balance and steric stabilization after incorporation of long alkyl chain. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of polydimethylsiloxane nanolatices by emulsion polymerization in a water–aminoethanol system

Stable and translucent polydimethylsiloxane nanolatices in a water–aminoethanol (AE) system were prepared by the emulsion polymerization of octamethylcyclotetrasiloxane (D₄) with nonionic polyoxyethylene alcohol ethers and polyoxyethylene aryl ether as surfactants and with KOH as an initiator. The effects of the AE concentration on the emulsion polymerization rate (R_p) of D₄ and the physical properties of the resultant nanolatices were investigated. Increasing the AE concentration in the reaction mixture dramatically increased the emulsion R_p value of D₄, and the kinetics of the D₄ emulsion polymerization in this system were consistent with the Morgan–Kaler theory of microemulsion polymerization. When the AE concentration in the emulsion increased, the transparency value of the resultant emulsion increased, and the size of the droplets in the resultant nanolatices decreased. In addition, the molecular weight of the polysiloxane in the resultant emulsion also increased with the increase in the AE concentration in the reaction mixture. A nanolatex prepared by the emulsion polymerization of 0.98M D₄ with 185 g/L AE had a transparency value of 80.9% and a mean diameter of 59.5 nm. The morphology of polysiloxane nanolatices cured with (N,N‐diethylaminomethyl)‐triethoxysilane was observed with transmission electron microscopy, and the size of the globular particles was consistent with that obtained by dynamic light scattering. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 347–352, 2005     

Thermoresponsive and magnetic molecularly imprinted polymers based on iron oxide encapsulated carbon nanotubes as a matrix for the selective adsorption and controlled release of 2,4,5‐trichlorophenol

Thermoresponsive and magnetic molecularly imprinted polymers (TMMIPs) based on magnetic carbon nanotubes (MCNTs) were prepared and applied to the switched recognition and controlled release of 2,4,5‐trichlorophenol (2,4,5‐TCP) from aqueous solution. In this study, MCNTs were first synthesized via the encapsulation of Fe₃O₄ nanoparticles into the tunnel of carbon nanotubes by a wet impregnation technology. Then, the TMMIPs were synthesized with N‐isopropyl acrylamide as a thermal functional monomer by free‐radical polymerization. The magnetic sensitivity and stability of the prepared materials were tested with a vibrating sample magnetometer (saturation magnetization = 1.4 emu/g) and atomic absorption spectrophotometer (in the pH range 3.0–8.0), respectively. The thermoresponsive properties of the TMMIPs were evaluated by two means, including the results of ultraviolet–visible spectroscopy and the controlled release of 2,4,5‐TCP at 30 and 40°C, respectively. The effects of the pH, initial concentration, and contact time on adsorption were examined with batch mode experiments, and several other compounds were selected as model analytes to evaluate the selective recognition performance of the TMMIPs. This demonstrated that the TMMIPs had a higher affinity for 2,4,5‐TCP than did the thermoresponsive and magnetic nonimprinted polymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42087.     

Low temperature one‐step synthesis of poly(barbituric acid) functionalized magnetic nanoparticles for removal of heavy metal ions

Poly(barbituric acid) functionalized magnetic nanoparticles with excellent adsorption behavior were facilely synthesized through one‐step chemical oxidation polymerization method by using sodium borohydride as the reducing agent. Structure, morphology, and magnetism of the products were thoroughly investigated by means of FTIR, FESEM, EDX, X‐ray photoelectron spectra, thermogravimetric analyzer–differential scanning calorimetry, and vibrating sample magnetometer. The products were of a sphere‐shaped nanostructure with the saturation magnetization value of 7.5 emu g^?1, which make them reusable for adsorption application. Removal capability for heavy metal ions were systematically evaluated using Pd (II) and Cu (II) ions as the models. The maximum sorption capacities by applying the Langmuir equation were calculated to be 166.6 mg/g for Cu (II) and 142.8 mg/g for Pb (II). A recycle test revealed that the PBA‐MNPs have above 87.1% for Cu (II) and 82.69% for Pb (II) ion desorption efficiency after the three regeneration cycle process. All the above experimental results demonstrated that barbituric acid‐based material could be used as a possible adsorbent for the efficient removal of heavy metals from aqueous solution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40957.     

无机-有机纳米复合乳液的原位聚合及其应用

综述了原位乳液聚合法制备无机．有机纳米复合乳液的技术现状及其形成机理，并运用此技术合成了舍无机纳米粒子的压敏胶用无机-有机纳米复合乳液，分析了纳米粒子在制备过程中的分散性能，从纳米粒子引入方式、乳化剂用量、纳米粒子加入量3方面对压敏胶性能进行考查。     

A molecular imprinted polymer on the surface of superparamagnetic Fe3O4–graphene oxide (MIP@Fe3O4@GO) for simultaneous recognition and enrichment of evodiamine and rutaecarpine in Evodiae fructus

A composite material (MIP@Fe₃O₄@GO) based on molecular imprinted polymer (MIP), superparamagnetic Fe₃O₄ particles and graphene oxide (GO) was prepared by the chemical coprecipitation method, and used to simultaneously separate and enrich two alkaloids (evodiamine and rutaecarpine) in the extract of Evodiae fructus. The as‐prepared MIP@Fe₃O₄@GO was characterized by Fourier transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The adsorption kinetics, isotherms, competitive adsorption, and reusability of MIP@Fe₃O₄@GO were also investigated. The results revealed that MIP@Fe₃O₄@GO was sensitive to the magnetic field and could be easily separated using an external magnet; MIP@Fe₃O₄@GO showed good recognition selectivity, as well as simultaneous enrichment and separation abilities for evodiamine and rutaecarpine in the extract of E. fructus with satisfactory recoveries. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44465.     

Comparison of gas‐ and liquid‐phase polymerization of propylene with heterogeneous metallocene catalyst

Sorption measurements are executed to study the sorption behavior of propylene in a semicrystalline polymer. Decreasing values for the Flory–Huggins interaction parameter with increasing temperature are obtained. Large deviations are found, especially at higher temperatures, compared to data from the literature. Propylene is polymerized in liquid and gaseous propylenes with Me₂Si[Ind]₂ZrCl₂/MAO/SiO₂ as the metallocene catalyst. Lower relative reaction rates are found in the gas phase compared to the experiments in the liquid phase. The activation energies from the experiments in both phases are on the same order of magnitude. However, the literature versus experimental sorption data has a large effect on the determined kinetic parameters. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1193–1206, 2001     

Novel kind of functional gradient poly(ε‐caprolactone) polyurethane nanocomposite: A shape‐memory effect induced in three ways

Multiwalled carbon nanotube (MWCNT) crosslinked polyurethane nanocomposites filled with iron (Fe) powders were synthesized by an in situ polymerization method. The Fe powders were deposited on one side of the nanocomposites during sample formation. Because of the gradient distribution of the Fe powders, the polymer part was affected little; this resulted in good mechanical properties of the nanocomposites. The electrical conductivities on each side of the nanocomposites were different. Because of the good magnetic properties and high electrical conductivities of the nanocomposites, the shape‐memory effect could be induced by temperature heating (temperature = 45°C), electrically resistive Joule heating (voltage (U) = 30 V), and magnetic field heating (frequency (f) = 45 kHz, intensity of magnetic field (H) = 46.5 kA/m). The shape‐memory properties were dependent on the location of the side that contained the most Fe powders (Fe side), and the nanocomposites showed better shape‐memory properties when the Fe side was located inside of the folded samples. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40220.     

Controlled release of protein from magnetite–chitosan nanoparticles exposed to an alternating magnetic field

In this research, the controlled release of proteins from magnetite (Fe₃O₄)–chitosan (CS) nanoparticles exposed to an alternating magnetic field is reported. Fe₃O₄–CS nanoparticles were synthesized with sodium tripolyphosphate (TPP) molecules as a crosslinking reagent. Bovine serum albumin (BSA) was used as a model protein, and its controlled release studied through the variation of the frequency of an alternating magnetic field. The results show the successful coating of CS and BSA on the Fe₃O₄ nanoparticles with an average diameter of 50 nm. Intermolecular interactions of TPP with CS and BSA were confirmed by Fourier transform infrared spectroscopy. The application of low‐frequency alternating magnetic fields to such magnetic CS nanoparticles enhanced the protein release properties, in which the external magnetic fields could switch on the unloading of these nanoparticles. We concluded that enhanced BSA release from nanoparticles exposed to an alternating magnetic field is a promising method for achieving both the targeted delivery and controlled release of proteins. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43335.     

Self film‐forming and opaque hollow latexes fabricated via seeded emulsion polymerization followed by alkali post‐treatment

In order to obtain novel hollow latexes with both opaque and self film‐forming properties, the four‐layer core/shell latex particles—sequentially consisting of a high carboxyl‐containing soft core, a transition layer, a rigid supporting layer, and an outermost film‐forming layer—are first designed and prepared by emulsion polymerization, and then treated with alkali to fabricate self film‐forming hollow latexes. On the basis of the previous research on the three‐layer core/shell latex, influences of the composition and thickness of the film‐forming layer on the properties and morphologies of the four‐layer core/shell and the final hollow latexes are investigated. Results show that under optimized conditions with butyl acrylate/styrene (BA/St) mass ratio of 2/1, divinyl benzene (DVB) content of 1 wt %, and core/film‐forming layer mass ratio of 1/6 in the film‐forming layer preparation, the final hollow latex particles exhibit best morphology considering both light scattering efficiency and film‐forming capability at room temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42541.     

Synthesis and properties of styrene–butylacrylate emulsion copolymers modified by silane compounds

Styrene (St)/butyl acrylate (BA) copolymers were prepared by adding triethoxyvinylsilane (TEVS), trimethoxyvinylsilane (TMVS), and triphenylvinylsilane (TPVS), each one through emulsion copolymerization. The polymerization was performed with methacrylic acid and auxiliary agents at 80°C in the presence of potassium peroxodisulfate as the initiator. Nonylphenol ethylene oxide‐40 units (NP‐40) and sodium lauryl sulfoacetate were used as nonionic and anionic emulsifiers, respectively. The resulting copolymers were characterized by using Fourier transform infrared spectroscopy. Thermal properties of the copolymers were studied by using thermogravimetric analysis and differential scanning calorimetry. The morphology of copolymers was also investigated by optical microscopy, and then the effects of silicone kinds and concentrations on the properties of the St/BA emulsion copolymers were discussed. The obtained copolymers have high solid content (50 %) and can be used in emulsion paints as a binder. The comparison of three different vinyl silanes indicates that the TEVS influences on the copolymer properties more than the others. The calculations of monomer conversion and monomer conversion versus time histories indicate that by increasing the silicone concentration, the polymerization rate decreases. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization of epoxy–clay hybrid composite prepared by emulsion polymerization

This article demonstrates the direct intercalation of an epoxy polymer in the interlayer of Na⁺–montmorillonite (MMT) by a step type of polymerization in an aqueous emulsion media. The synthesis and the results of structural and thermal characterizations for this hybrid composite are described. Equimolar quantities of bisphenol A and an epoxy prepolymer (n = 0.2) in an emulsion media were polymerized in the presence of Na⁺–MMT. X-ray diffraction (XRD) data obtained from the acetone-extracted products show that the basal spacing of the MMT is expanded from 0.96 to 1.64 nm. Thermal characterization for the postcured products by TGA and DSC gave evidence of enhanced thermal stabilities. SEM examination of the uncured products revealed that a disordered phase begins to appear with increasing polymer loading. However, the XRD profile supported that an overwhelming fraction of the nanocomposite contains intercalated clay. Also, the possibility of intercalation by the emulsion technique is proposed on the basis of the swelling characteristics of MMT in aqueous media and the sizes of micelles containing a monomer. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1997–2005, 1998     

Preparation and investigation of structural,magnetic, and microwave absorption properties of aluminum‐doped strontium ferrite/MWCNT/polyaniline nanocomposite at KU‐band frequency

Aluminum‐doped strontium hexaferrite nanoparticle SrAl_1.3Fe_10.7O₁₉ was prepared by sol–gel method and polyaniline (PANi) multiphase magnetic nanocomposite SrAl_1.3Fe_10.7O₁₉/MWCNT/PANi was synthesized through a sonochemical method by in situ polymerization. The morphology, structure, and magnetic properties of the nanocomposites are investigated by field emission scanning electron microscopy, X‐ray powder diffraction, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. The electromagnetic interference shielding efficiency was evaluated in the KU‐band (12.4–18 GHz). The reflection loss (RL) value showed that the composites have an excellent absorbing property in the KU‐band, minimum ?24.93 dB at 16.40 GHz with a bandwidth of 2.81 GHz (shielding effectiveness up to 10 dB) at a matching thickness 6.5 mm. The RL value of the SrAl_1.3Fe_10.7O₁₉/MWCNT nanocomposite was ?15.92 dB at 15.84 GHz with a bandwidth of 1.66 GHz (with a shielding effectiveness up to 10 dB). These results disclose the remarkable microwave shielding ability of SrAl_1.3Fe_10.7O₁₉/MWCNT/PANi in KU‐band due to the interactive effect of the three components. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45135.     

Revisiting emulsion polymerization to produce stable,translucent, nanolatex of partially water‐soluble monomers,ethylacrylate–methylmethacrylate

Stable, translucent nanolatex with monomer weight % as high as 25 was obtained through emulsion copolymerization of partially water‐soluble monomers, ethyl acrylate and methylmethacrylate. The kinetics of reaction, studied at monomer/surfactant (M/S) ratio 10 and 50 showed two intervals and higher rate of particle nucleation for KPS initiated systems. However, AIBN initiated system showed phase separation. The copolymer composition was determined through ¹H‐NMR studies and copolymers showed two glass transition temperatures. Dynamic light scattering studies indicated bimodal distribution of polymer particle size. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2593–2603, 2003