Preparation and characterization of poly(chlorotrifluoroethylene‐co‐ethylvinyl ether)/poly(styrene acrylate) core–shells and SiO2 nanocomposite films via a solution mixing method

Nanocomposite particles of poly(chlorotrifluoroethylene‐co‐ethylvinyl ether) [poly(CTFE‐co‐EVE)]/poly(styrene acrylate) (PSA)/SiO₂ were prepared with poly(CTFE‐co‐EVE)/PSA [CS(FS); core–shell (CS) fluoro surfactant (FS)] and hydrophilic SiO₂ nanoparticles by a solution mixing method. This method yielded a homogeneous dispersion of hydrophilic SiO₂ nanoparticles in the CS(FS) matrix. The nanocomposite particle composition was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. A slight improvement in the thermal stability was observed and the glass‐transition temperature of the nanocomposite particles increased compared with the CS(FS) matrix. A remarkable enhancement was observed in the mechanical properties with an increase in the tensile strength from 1.1 to 6.2 MPa and with an increase in the elongation at break from 209.6 to 350.1% for the films with 15 wt % SiO₂. The presence of a wettable PSA shell on the fluorocore made interaction possible with SiO₂; this made it more hygroscopic with a decent water uptake capacity and an enhanced water contact angle. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

Thermal,mechanical, and dielectric properties of aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) layered composites

In this study, a novel aluminum phosphate (AlPO₄) heat‐resistant layer reinforced with aluminum silicate fiber (ASF) was successfully compounded on a poly(ether sulfone) (PES) matrix via the preparation process of high‐temperature heat treatment and vacuum hot‐pressing sintering technique. The influence of the ASF content on the morphology, thermal, mechanical, and dielectric properties of the as‐fabricated aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) (ASF/AlPO₄–PES) layered composite was investigated. The results reveal that the incorporation of aluminum silicate fiber/aluminum phosphate (ASF/AlPO₄) heat‐resistant layer can significantly improve the thermal stability and mechanical performances of the PES matrix composites. Compared with the pristine PES, the ASF/AlPO₄–PES layered composite containing 8.0 wt % ASF exhibited better high‐temperature resistance properties (300 °C) and a lower thermal conductivity (0.16 W m^?1 K^?1). Furthermore, the dielectric constant and dielectric loss tangent of this PES matrix composite decreased to 2.16 and 0.007, respectively. Meanwhile, the frequency stability of the dielectric properties for the ASF/AlPO₄–PES layered composites was remarkably enhanced with increasing ASF addition at frequencies ranging from 10² Hz to 5 MHz. This was attributed to the existence of microscopic pores within the ASF/AlPO₄ layer and the strong interfacial bonding between the ASF/AlPO₄ layer and the PES matrix. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45542.     

Biodegradable magnetic‐sensitive shape memory poly(ɛ‐caprolactone)/Fe3O4 nanocomposites

A novel biodegradable magnetic‐sensitive shape memory poly(?‐caprolactone) nanocomposites, which were crosslinked with functionalized Fe₃O₄ magnetic nanoparticles (MNPs), were synthesized via in situ polymerization method. Fe₃O₄ MNPs pretreated with γ‐(methacryloyloxy) propyl trimethoxy silane (KH570) were used as crosslinking agents. Because of the crosslinking of functionalized Fe₃O₄ MNPs with poly(?‐caprolactone) prepolymer, the properties of the nanocomposites with different content of functionalized Fe₃O₄ MNPs, especially the mechanical properties, were significantly improved. The nanocomposites also showed excellent shape memory properties in both 60 °C hot water and alternating magnetic field (f = 60, 90 kHz, H = 38.7, 59.8 kA m^?1). In hot water bath, all the samples had shape recovery rate (R_r) higher than 98% and shape fixed rate (R_f) nearly 100%. In alternating magnetic field, the R_r of composites was over 85% with the highest at 95.3%. In addition, the nanocomposites also have good biodegradability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45652.     

Comparative study of the effects of experimental variables on growth rates of aluminum and iron hydroxide flocs during coagulation and their structural characteristics

In this study, the dimensions of over six thousand flocs were analyzed to quantitatively and comparatively investigate the effects of several experimental variables on the growth rate of aluminum (Al) and ferric (Fe) hydroxide flocs. Results show that Fe hydroxide flocs have faster growth rate than Al hydroxide flocs; and the average size of the former is larger than that of the latter. Increasing the concentration of the bivalent sulfate ion (SO₄²⁻), initial turbidity, or slow mixing rate, was able to increase the growth rate of both kinds of flocs. On the other hand, steady floc sizes were found to decrease with the increase in SO₄²⁻ concentration, initial turbidity, or shear rate. Fe hydroxide flocs are more prone to be influenced by the changes in the variables than Al hydroxide flocs. While the steady floc sizes became smaller when initial turbidity or slow mixing speed increased, the roundness and smoothness of flocs were found to increase, indicating that higher initial turbidity or larger slow mixing rate produces flocs with more regular and round shape. Furthermore, at a fixed shear rate, Fe hydroxide flocs are stronger than Al hydroxide flocs. However, Fe hydroxide floc sizes are much easier to decrease with the increase in slow mixing intensity.     

Layered double hydroxide/NaSb(OH)6–poly(vinyl chloride) nanocomposites: Preparation,characterization, and thermal stability

A novel layered double hydroxide/NaSb(OH)₆‐based nanocomposite (Sb‐LDH) has been prepared via intercalation of thio‐antimonite (SbS₃^3?) and reconstruction of LDH using Mg‐Al LDH as precursors. It is composed of LDH nanolayers with thickness of 25 nm and NaSb(OH)₆ nanoparticles with diameter of 3–25 nm. The presence of NaSb(OH)₆ will decrease the decomposition intensity and hinder the decomposition of Mg‐Al LDH because of the potential synergetic effect. When applied to poly(vinyl chloride) (PVC) composites, both Mg‐Al LDH and Sb‐LDH can enhance the thermal stability and increase the decomposition temperature of PVC. Compared with Mg‐Al LDH, Sb‐LDH results in higher decomposition temperatures and whiteness and higher initial and long‐term stabilities due to the presence of NaSb(OH)₆, which can react with HCl and coordinate with Cl in the PVC chains. Because Mg‐Al LDH will accelerate the dehydrochlorination of PVC driving by the Lewis acid such as AlCl₃, the thermal stability of PVC decreases with increasing nanofiller loading. When 1 wt % Sb‐LDH was added, the color change time and Congo red time of PVC composites are 140 min and 154 min, respectively. With enhanced thermal stabilization, this novel LDH nanocomposite could gain promising application in thermal stabilizer for PVC resins. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Magnetic heat resistant poly(amide–imide) nanocomposite derived from bisphenol A: Synthesis and properties

New magnetic and heat resistant poly(amide–imide) nanocomposite (PAIN) was prepared from Fe₃O₄ nanoparticles and poly(amide‐imide) (PAI) in a solution of N‐methyl‐2‐pyrrolidone. New PAI derived from bisphenol A containing aryl sulfone and ether moiety was synthesized from 2,2′‐(4,4′‐(4,4′‐(propane‐2,2‐diyl)bis(4,1‐phenylene))bis(oxy)bis(4,1‐phenylene))bis(1,3‐dioxoisoindoline‐5‐carboxylic acid) 5 as a new diacid and 4,4′‐diaminodiphenyl sulfone by direct polycondensation reaction. Fe₃O₄ nanoparticles were prepared by coprecipitation method and characterized using Fourier transform infrared, X‐ray diffraction, scanning electron microscopy (SEM), and vibrating samples magnetometer (VSM). The new poly(amide‐imide)/Fe₃O₄ nanocomposite was characterized using SEM, FTIR, and VSM. The effect of Fe₃O₄ nanoparticles on the thermal properties of PAI was studied using thermogravimetric analysis and differential scanning calorimeter. POLYM. COMPOS., 34:1682–1689, 2013. © 2013 Society of Plastics Engineers     

Gold deposition on Fe3O4/(co)Poly(N‐octadecyl methacrylate) hybrid particles to obtain nanocomposites With ternary intrinsic features

Here, nanocomposite particles with three domains including magnetite nanoparticles, poly(N‐octadecyl methacrylate) (PODMA) or poly(N‐octadecyl methacrylate‐co‐1‐vinylimidazole) (P(ODMA‐co‐VIMZ)), and gold nanoparticles were prepared. Fe₃O₄ nanoparticles with narrow particle size distribution were prepared through a synthetic route in an organic phase in order to achieve good control of the size and size distribution and prevent their aggregation during their preparation. These magnetite nanoparticles, ～ 5 nm in size, were then encapsulated and well‐dispersed in PODMA and P(ODMA‐co‐VIMZ) matrices via a miniemulsion polymerization process to obtain the corresponding nanocomposite particles. The results revealed that Fe₃O₄ nanoparticles were encapsulated and did not migrate towards the monomer/water interface during polymerization. The resulting latex was used as a precursor for the adsorption of Au³⁺ ions on the surface of the polymeric particles and subsequent reduction to produce Fe₃O₄/P(ODMA‐co‐VIMZ)/Au nanocomposite particles. The morphology of the particles from each step was fully characterized by TEM and AFM, and the results of DLS analysis showed their size and size distribution. Measurement of magnetic properties illustrated the superparamagnetic characteristic of the products and it was observed that the encapsulation process and deposition of gold had no effect on the magnetic properties of the resulting particles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Method for preparing polyaluminocarbosilane

Polyaluminocarbosilane (PACS) was synthesized directly by the one‐pot reaction of polydimethylsilane (PDMS) with aluminum acetylacetonate [Al(acac)₃] in an autoclave. In this closed system, all the aluminum in Al(acac)₃ was converted into PACS. Therefore, the content of aluminum could be readily controlled quantitatively. On the basis of Fourier transform infrared, ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, and ²⁷Al magic‐angle spinning NMR analysis, the reaction mechanism was proposed as follows: PDMS dissociated during pyrolysis to generate silicon free radicals, and then they reacted with Al(acac)₃ to yield PACS containing (Si? O)_nAl groups (n = 4, 5, or 6). Meanwhile, these reactions resulted in the cleavage of O? C and/or O?C bonds in Al(acac)₃. Some of the free‐radical fragments generated by this cleavage continued to react with the silicon free radicals and were incorporated into the structural units of PACS; the rest of them may have been converted into small oxygen‐containing compounds, which were removed in the subsequent processing after the reactions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Magnetic chitosan-based aerogel decorated with polydimethylsiloxane: A high-performance scavenger for oil in water

Most ingredients used to construct porous substrate of hydrophobic magnetic absorbent for oil/water separation are toxic, environmentally incompatible and difficult to degrade. With the purpose of solving this problem, a magnetic chitosan (CS)-based aerogel decorated with polydimethylsiloxane (PDMS) was successfully fabricated in this work. The magnetic porous substrate was built by the electrostatic interactions between CS, itaconic acid and Fe₃O₄ nanoparticles (FeNPs) in water solution, followed by a freeze-drying process. The hydrophobic properties were rendered to the substrate by the crosslinking reaction of PDMS. Owing to the low density (0.0655 g/cm³) and high porosity (92%), the prepared aerogel displayed high absorption capacities (8.89–22.38 g/g) towards the testing organic liquids. The silylation process provided the aerogel with excellent hydrophobic properties (water contact angle, 147.1°), resulting in selectively absorbing oil from immiscible oil/water mixture and water-in-oil emulsion. Due to the uniformly distributed FeNPs, the remote control of the aerogel by external magnetic field was acquired, the saturation magnetization of which was 11.22 emu/g. Furthermore, the aerogel could also continuously separate heavy oil from water by acting as filter. The experimental results indicate that this renewable, environmentally benign and bifunctional aerogel has great potential in oily wastewater remediation.     

Characterization of stabilized porous magnetite core–shell nanogel composites based on crosslinked acrylamide/sodium acrylate copolymers

Stabilized and dispersed superparamagnetic porous nanogels based on sodium acrylate (AA‐Na) and acrylamide (AM) in a surfactant‐free aqueous system were synthesized via solution polymerization at room temperature. The formation of magnetite nanoparticles was confirmed and their properties characterized using Fourier transform infrared spectroscopy. Extensive characterization of the magnetic polymer particles using transmission electron microscopy (TEM), dynamic light scattering and zeta potential measurements revealed that Fe₃O₄ nanoparticles were incorporated into the shells of poly(AM/AA‐Na). The average particle size was 5–8 nm as determined from TEM. AM/AA‐Na nanoparticles with a diameter of about 11 nm were effectively assembled onto the negatively charged surface of the as‐synthesized Fe₃O₄ nanoparticles via electrostatic interaction. Crosslinked magnetite nanocomposites were prepared by in situ development of surface‐modified magnetite nanoparticles in an AM/AA‐Na hydrogel. Scanning electron microscopy was used to study the surface morphology of the prepared composites. The morphology, phase composition and crystallinity of the prepared nanocomposites were characterized. Atomic force microscopy and argon adsorption–desorption measurements of Fe₃O₄.AM/AA indicated that the architecture of the polymer network can be a hollow porous sphere or a solid phase, depending on the AA‐Na content. © 2013 Society of Chemical Industry     

Synthesis mechanisms of poly[styrene‐co‐(acrylic acid)]‐supported TiCl4 catalysts modified by magnesium compounds

Soluble poly[styrene‐co‐(acrylic acid)] (PSA) modified by magnesium compounds was used to support TiCl₄. For ethylene polymerization, four catalysts were synthesized, namely PSA/TiCl₄, PSA/MgCl₂/TiCl₄, PSA/(n‐Bu)MgCl/TiCl₄, and PSA/(n‐Bu)₂Mg/TiCl₄. The catalysts were characterized by a set of complementary techniques including X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and element analysis. Synthesis mechanisms of polymer‐supported TiCl₄ catalysts were proposed according to their chemical environments and physical structures. The binding energy of Ti 2p in PSA/TiCl₄ was extremely low as TiCl₄ attracted excessive electrons from ? COOH groups. Furthermore, the chain structure of PSA was destroyed because of intensive reactions taking place in PSA/TiCl₄. With addition of (n‐Bu)MgCl or (n‐Bu)₂Mg, ? COOH became ? COOMg‐ which then reacted with TiCl₄ in synthesis of PSA/(n‐Bu)MgCl/TiCl₄ and PSA/(n‐Bu)₂Mg/TiCl₄. Although MgCl₂ coordinated with ? COOH first, TiCl₄ would substitute MgCl₂ to coordinate with ? COOH in PSA/MgCl₂/TiCl₄. Due to the different synthesis mechanisms, the four polymer‐supported catalysts correspondingly showed various particle morphologies. Furthermore, the polymer‐supported catalyst activity was enhanced by magnesium compounds in the following order: MgCl₂ > (n‐Bu)MgCl > (n‐Bu)₂Mg > no modifier. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

pH Responsive Behavior of Fe3O4@PDEA-PEGMA Core-Shell Hybrid Magnetic Nanoparticles

Fe₃O₄@PDEA-PEGMA core-shell magnetic nanoparticles were prepared via surface-initiated atom transfer radical polymerization (ATRP). First, an ATRP initiator was immobilized onto the surface of Fe₃O₄ magnetic nanoparticles, then poly[2-(diethylamino)ethyl methacrylate] (PDEA) and poly(poly[(ethylene glycol) monomethacrylate]) (PEGMA) were grafted from the surface of the magnetic nanoparticles in succession. Each step of the reactions gave distinctive thermogravimetric analysis curves. Polymer shells cleaved from Fe₃O₄ core were measured by gel permeation chromatography, while its molecular weight was found to increase with successive polymerization (with a polydispersity of approximately 1.3–1.4). The architecture of the core-shell nanoparticles was confirmed by transmission electron microscopy. The Fe₃O₄@PDEA-PEGMA hybrid magnetic nanoparticles formed stable dispersions in H₂O at low pH (pH < 6) and precipitated out at high pH (pH > 6). This pH transition behavior was also observed in dynamic light scattering experiments.     

Polyurethanes and polyesters from lignin

Lignin, obtained through steam explosion from straw, was completely characterized via elemental analysis, gel permeation chromatography, ultraviolet and infrared spectroscopy, and ¹³C and ¹H nuclear magnetic resonance spectrometry. Polyurethanes were obtained by treating steam‐exploded lignin from straw with 4,4′‐methylenebis(phenylisocyanate), 4,4′‐methylenebis(phenylisocyanate) –ethandiol, and poly(1,4‐butandiol)tolylene‐2,4‐diisocyanate terminated. The obtained materials were characterized by using gel permeation chromatography, infrared spectroscopy, and scanning electron microscopy. Differential scanning calorimetry analysis showed a T_g at ?6°C, assigned to the glass transition of the poly(1,4‐butandiol) chains. The presence of ethylene glycol reduced the yields of the polyurethanes. The use of the prepolymer gave the best results in polyurethane formation. Steam‐exploded lignin was used as the starting material in the synthesis of polyesters. Lignin was treated with dodecanoyl dichloride. The products were characterized by using gel permeation chromatography, infrared spectroscopy, ¹³C and ¹H nuclear magnetic resonance spectrometry, and scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1451–1456, 2005     

Application of magnetite modified with aluminum/silica to adsorb phosphate in aqueous solution

BACKGROUND: Phosphate is one of the main contaminants responsible for the eutrophication of surface waters, and adsorption is a potential treatment method for this pollutant. A magnetic adsorbent manufactured from magnetite (Fe₃O₄) can be recovered easily from treated water by magnetic force, without requiring further downstream treatment. In this research, the surface of magnetite modified with aluminum and silica (Al/SiO₂/Fe₃O₄) was used to adsorb phosphate in an aqueous solution in a batch system. RESULTS: The optimum solution pH for phosphate adsorption by Al/SiO₂/Fe₃O₄ was found to be 4.5. The phosphate adsorption behavior of Al/SiO₂/Fe₃O₄ was in good agreement with both the Langmuir and Freundlich adsorption isotherm, and the maximum adsorption capacity (q_m) and Gibbs free energy of phosphate was 25.64 mg g^?1 and ? 21.47 kJ mol^?1, respectively. A pseudo‐second‐order model could best describe the adsorption kinetics, and the derived activation energy was 3.52 kJ mol^?1. The optimum condition to desorb phosphate from Al/SiO₂/Fe₃O₄ is provided by a solution with 0.05 mol L^?1 NaOH. CONCLUSIONS: Magnetic adsorbent is a potential material for a water treatment method. The results of this study will be helpful in the development of aluminum modified silica magnetic adsorbents that can be used to remove phosphate in aqueous solution. Copyright © 2011 Society of Chemical Industry     

Cr(III)‐containing Fe3O4/mercaptopropanoic acid‐poly(2‐hydroxyethyl acrylate) nanocomposite: Highly active magnetic catalyst for direct hydroxylation of benzene

In this study, polymer‐grafted magnetic nanoparticles containing chromium(III) ions incorporated onto Fe₃O₄/mercaptopropanoic acid‐poly(2‐hydroxyethyl acrylate) was prepared via a simple and in situ method. The obtained magnetic nanocomposite exhibited high catalytic activity and excellent selectivity in direct hydroxylation of benzene in the presence of hydrogen peroxide under solvent‐free condition. The magnetic catalyst could be also separated by an external magnet and reused seven times without any significant loss of activity/selectivity. Due to the Lewis acidity of the Fe³⁺ groups in the structure of magnetic nanoparticles, the high efficiency of this catalyst is possibly due to the synergetic effect of Cr³⁺ and Fe³⁺ groups in the structure of magnetic nanocomposite. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40383.     

Development of a new magnetic aluminum matrix nanocomposite

This article presents the results of a comparative investigation on microstructure, mechanical properties and magnetic characteristics of aluminum matrix nanocomposites reinforced with nickel ferrite nanoparticles. Magnetic nickel ferrite (NiFe₂O₄) nanoparticles with average size of 35?nm were synthesized via citrate-nitrate route and were used as the reinforcement phase in commercially pure aluminum matrix. Aluminum matrix samples with 0, 1, 2.5, 5 and 10?wt% ceramic reinforcement were fabricated using the powder metallurgy process. The sintered samples were then extruded at 400?°C to improve the density and homogeneity of the composite. Optical microscopy, SEM, FESEM, densitometry, XRD, DSC and VSM analyses were all used to evaluate the microstructure, porosity distribution, density, existing phases, possible reactions between the matrix and the reinforcements and magnetic properties of the samples. The results showed that the relative density of the composites decreased as the reinforcement weight percent was increased. The samples yield stress and ultimate tensile strength increased by increasing the weight percent of the reinforcement up to 5?wt%, however, they dropped at 10?wt% reinforcement content. The compressive yield stress, magnetization and coercivity of the composites were all observed to increase as the reinforcement content increased. However, the elongation of composite samples decreased considerably as the reinforcement content increased.     

Synthesis of polyaluminocarbosilane and reaction mechanism study

Polyaluminocarbosilane (PACS) as the precursor of high‐temperature resistant SiC fibers was synthesized by reacting polycarbosilane (PCS) with aluminum(III)acetylacetonate [Al(AcAc)₃] at 310°C in N₂ under ambient pressure. The reaction mechanism and the structure of PACS were investigated in detail by FTIR, GPC, GC/MS, ESCA, and elemental analysis. The reaction was proven complex involving the formation of Si? O? Al and Si? Al? Si bonds, which were accompanied by the evolution of 3‐methoxy‐2,2‐dimethyl‐oxirane, 2,3‐dihydro‐[1,4]dioxine, pent‐3‐en‐2‐one, and 3‐ethyl‐but‐3‐en‐2‐one, and acetylacetone. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2787–2792, 2002     

Octakis(ethynyldimethylsiloxy) silsesquioxane: Synthesis and application in poly(silicane arylacetylene) resin

Octakis(ethynyldimethylsiloxy)silsesquioxane (OEMS) was first synthesized via hydrolysis condensation reaction between tetramethylammonium octaanion and ethynyldimethylchlorosilane, and characterized by FT‐IR, NMR, and GPC methods. A series of OEMS modified poly(silicane arylacetylene) resins (OEMS‐PSAs) were prepared from OEMS and poly(silicane arylacetylene) (PSA). TEM analysis of the OEMS‐PSAs confirms that the nano‐sized polyhedral oligomeric silsesquioxanes (POSS) are dispersed evenly in low content, but aggregated unregularly in high content in OEMS‐PSAs. The curing behavior of OEMS‐PSAs was studied with DSC and FT‐IR techniques. Nanoindentation test shows the incorporation of OEMS into PSA could decrease both of the elastic modulus and surface hardness of the PSA thermoset. The dielectric constants (?_r) of the OEMS‐PSA thermosets approach to 2.1, depending on not only the content of POSS but also the dispersion of POSS. Furthermore, TGA results demonstrate the OEMS‐PSA thermosets possess the certain thermo‐oxidative resistance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44158.     

Synthesis and characterization of emulsion polymerized mixed matrix aluminum silicate/poly(2,6‐dimethyl 1,4‐phenylene oxide) films

A series of poly (2,6‐dimethyl‐1,4‐phenylene oxide) (PPO)‐based organic/inorganic films for the potential application in membrane gas separation were prepared by employing a method in which aluminum hydroxonitrate contained in a stable water‐in‐oil (W/O) emulsion, the oil phase being a solution of PPO in trichloroethylene, was mixed with a homogeneous solution of PPO in trichloroethylene containing tetraethyl orthosilicate (TEOS). Inorganic polymerization occurred in or at the surface of the aqueous droplets of the W/O emulsion. Subsequently, thin films were prepared by a spin coating technique, and they were referred to as emulsion polymerized mixed matrix (EPMM) films. Scanning electron micrographs taken from a film cross section indicated the presence of particles in the PPO matrix, and energy dispersive X‐ray measurements showed that the embedded particles contained Al and Si elements. Differential scanning calorimetry analysis showed a decrease in the glass transition of the EPMM films with increase of TEOS loading. The compatibility between aluminum silicate nanoparticles and PPO in the EPMM films was confirmed by air separation tests. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermally and magnetically dual‐responsive mesoporous silica nanospheres: preparation,characterization, and properties for the controlled release of sophoridine

Novel thermally and magnetically dual‐responsive mesoporous silica nanoparticles [magnetic mesoporous silica nanospheres (M‐MSNs)–poly(N‐isopropyl acrylamide) (PNIPAAm)] were developed with magnetic iron oxide (Fe₃O₄) nanoparticles as the core, mesoporous silica nanoparticles as the sandwiched layer, and thermally responsive polymers (PNIPAAm) as the outer shell. M‐MSN–PNIPAAm was initially used to control the release of sophoridine. The characteristics of M‐MSN–PNIPAAm were investigated by transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetry, N₂ adsorption–desorption isotherms, and vibrating specimen magnetometry analyses. The results indicate that the Fe₃O₄ nanoparticles were incorporated into the M‐MSNs, and PNIPAAm was grafted onto the surface of the M‐MSNs via precipitation polymerization. The obtained M‐MSN–PNIPAAm possessed superparamagnetic characteristics with a high surface area (292.44 m²/g), large pore volume (0.246 mL/g), and large mesoporous pore size (2.18 nm). Sophoridine was used as a drug model to investigate the loading and release properties at different temperatures. The results demonstrate that the PNIPAAm layers on the surface of M‐MSN–PNIPAAm effectively regulated the uptake and release of sophoridine. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40477.