Equilibrium,kinetics, and thermodynamics of Pd(II) adsorption onto poly(m‐aminobenzoic acid) chelating polymer

This study describes the equilibrium, kinetics, and thermodynamics of the palladium(II) (Pd(II)) adsorption onto poly(m‐aminobenzoic acid) (p‐mABA) chelating polymer. The p‐mABA was synthesized by the oxidation reaction of m‐aminobenzoic acid monomer with ammonium peroxydisulfate (APS). The synthesized p‐mABA chelating polymer was characterized by FTIR spectroscopy, gel permeation chromatography (GPC), thermal analysis, potentiometric titration, and scanning electron microscopy (SEM) analysis methods. The effects of the acidity, temperature, and initial Pd(II) concentration on the adsorption were examined by using batch adsorption technique. The optimum acidity for the Pd(II) adsorption was determined as pH 2. In the equilibrium studies, it was found that the Pd(II) adsorption capacity of the polymer was to be 24.21 mg/g and the adsorption data fitted better to the Langmuir isotherm than the Freundlich isotherm. The kinetics of the adsorption fitted to pseudo‐second‐order kinetic model. In the thermodynamic evaluation of the adsorption, the ΔG° values were calculated as ?16.98 and ?22.26 kJ/mol at 25–55°C temperatures. The enthalpy (ΔH°), entropy (ΔS°), and the activation energy (E_a) were found as 35.40 kJ/mol, 176.05 J/mol K, and 61.71 kJ/mol, respectively. The adsorption of Pd(II) ions onto p‐mABA was a spontaneous, endothermic, and chemical adsorption process which is governed by both ionic interaction and chelating mechanisms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42533.     

Investigation on structure and properties of anion exchange membranes based on tetramethylbiphenol moieties containing copoly(arylene ether)s

Quaternary ammonium functionalized poly(arylene ether)s (QPAEs) containing 2,2′,6,6′‐tetramethylbiphenol moieties were designed and successfully synthesized via nucleophilic substitution polycondensation, bromination, quaternization and alkalization. The structure, water uptake, ion exchange capacities (IECs), hydroxide ion conductivities, and mechanical properties, as well as thermal and chemical stabilities of obtained QPAEs membranes were investigated. The QPAE‐a membrane with IEC value of 0.98 meq g^?1 demonstrated the highest ion conductivity (47.4 mS cm^?1) at 80°C. The ion transport activation energy (E_a) of QPAEs membranes varied from 8.57 to 19.95 kJ mol^?1. After chemical stability test conditioned in 1M NaOH at 60°C for 7 days, the QPAEs membranes except QPAE‐c (IEC = 0.88 meq g^?1) still exhibited high hydroxide ion conductivities (over 15 mS cm^?1) and acceptable tensile strength (～10 MPa). These properties indicate that the ionomers membranes are potential candidates for anion exchange membranes in anion exchange membrane fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41525.     

Mild functionalization of carbon nanotubes filled epoxy composites: Effect on electromagnetic interferences shielding effectiveness

The effect of nitric acid mild functionalized multiwalled carbon nanotubes (MWCNTs) on electromagnetic interference (EMI) shielding effectiveness (SE) of epoxy composites was examined. MWCNTs were oxidized by concentrated nitric acid under reflux conditions, with different reaction times. The dispersion of MWCNTs after functionalization was improved due to the presence of oxygen functional groups on the nanotubes surface. Functionalization at 2 h exhibits the highest EMI SE and electrical conductivity of MWCNTs filled epoxy composites. However, EMI shielding performance of MWCNTs filled epoxy composite declined when the functionalization reaction time was prolonged. This was due to extensive damage on the MWCNT structure, as verified by a Raman spectroscope. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42557.     

Dendrimer functionalized polysilane: An efficient and recyclable organocatalyst

Polysilane supported dendrimer was efficiently utilized as an organocatalyst for Knoevenagel condensation reaction. Polysilane support was synthesized by the polymerization of trichloromethylsilane. The polypropyleneimine (PPI) dendrimer was grafted on the polymer support by divergent method. The dendrimer was synthesized up to three generations (G3). The dendrimer functionalized polysilane (PS‐PPIG3) was found to contain high concentration of terminal amino groups. The catalytic activity of the PS‐PPIG3 dendrimer was generalized by conducting the Knoevenagel condensation reaction with diverse sets of substrates, and was found to be an efficient organocatalyst. The condensation product could be easily separated from the reaction medium because of the heterogeneous nature of the polymer support. The reaction conditions were optimized, and the catalyst was found to be reusable. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41593.     

Functionalization of hybrid poly(n‐isopropylacrylamide) hydrogels for Escherichia coli cell capture via adsorbed intermediate dye molecule

Poly(n‐isopropylacrylamide) Laponite (PNIPAM‐Lap) hybrid hydrogels, which use the synthetic clay Laponite as a crosslinker, permanently adsorb cationic laser dyes out of solution. This proof‐of‐concept expounds on this capability by adsorbing an intermediate dye molecule and using it as the foundation for successfully conjugating microbial antibodies to the surface of a PNIPAM hydrogel. The study involves using acriflavinium chloride molecules, adsorbed by a PNIPAM‐Lap hydrogel from an acriflavine laser dye solution, as an intermediate molecule to attach antibodies raised against E. coli to the hydrogel and demonstrate cell capture. Furthermore, this system exemplifies a novel biotechnological platform for greatly expanding PNIPAM hydrogels' capabilities and applicability through conjugation chemistry to surface‐bound molecules. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41557.     

Synthesis and application of streptavidin functionalized organosilica microparticles

This article reports on the chemical synthesis, functionalization and application of streptavidin (SA)‐coated organosilica microparticles. Thiol‐functionalized organosilica microparticles are synthesized via a two‐step approach involving acid‐catalyzed hydrolysis and condensation of 3‐mercaptopropyl trimethoxysilane (MPS), followed by base‐catalyzed condensation. The surfaces of these particles are modified with 3‐aminopropyltriethoxysilane (APS), and characterized by FTIR, XPS, and TGA. Then, APS‐functionalized microparticles are covalently coated with SAs by using glutaraldehyde as a coupling agent, and characterized by FTIR, SEM, and AFM. Immobilization of biotinylated λ DNA onto microparticles via SA‐biotin immuoreaction is confirmed by confocal microscopy. The results show that these SA‐functionalized organosilica microparticles are useful carriers for DNA manipulation at the single molecule level. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41560.     

Facile synthesis of functional copolymers with pendant vinyl groups by using asymmetrical divinyl monomers

Polymers bearing pendant vinyl groups have attracted significant attraction because they can be further modified for required applications, but their syntheses are still a big challenge. Herein, allyl methacrylate was catalyzed using a phosphazene base to homopolymerize or copolymerize with 2‐(N, N‐dimethylamino) ethyl methacrylate, affording vinyl functional polymers, which were further successfully tailored by the thiol–ene coupling reaction. The result showed that both the homopolymerizations and copolymerizations could proceed at room temperature with very high monomer conversions. The contents of pendant double bonds in the copolymers were approximately equal to the monomer feeds, but the LCST of the statistical copolymers linearly decreased with increasing AMA content. This strategy offered a new scalable and facile strategy for vinyl functional polymers, would have a wide practical application in many fields. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42758.     

Smart carboxymethylchitosan hydrogels that have thermo‐ and pH‐responsive properties

Thermo‐responsive poly(N‐isopropylacrylamide) (poly(NIPAAm)) and pH‐responsive poly(N,N′‐diethylaminoethyl methacrylate) (poly(DEAEMA)) polymers were grafted to carboxymethylchitosan (CMC) via radical polymerization to form highly water swellable hydrogels with dual responsive properties. Ratios of CMC, NIPAAm to DEAEMA used in the reactions were finely adjusted such that the thermo and pH responsiveness of the hydrogels was retained. Scanning electron microscopy (SEM) indicated the formation of an internal porous structure for the swollen CMC hydrogels upon incorporation of poly(NIPAAm) and poly(DEAEMA). Effect of temperature and pH changes on water swelling properties of the hydrogels was investigated. It was found that the water swelling of the hydrogels was enhanced when the solution pH was under basic conditions (pH 11) or the temperature was below its lower critical solution temperature (LCST). These responsive properties can be used to regulate releasing rate of an entrapped drug from the hydrogels, a model drug, indomethacin was used to demonstrate the release. These smart and nontoxic CMC‐based hydrogels show great potential for use in controlled drug release applications with controllable on‐off switch properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41505.     

Influence of polymer morphology on the adsorption behaviors of molecularly imprinted polymer‐methacrylic acid functionalized β‐cyclodextrin

The influence of molecularly imprinted polymer‐methacrylic acid functionalized β‐cyclodextrin (MIP(MAA‐β‐CD)) morphology on the adsorption behavior studies towards benzylparaben (BzP) was explored. The effects of time, concentration, and temperature towards BzP uptake were extensively evaluated. The adsorption performance of MIP(MAA‐β‐CD) was compared with that on the molecularly imprinted polymer‐methacrylic acid (MIP(MAA)) synthesized without β‐CD. The MIP(MAA‐β‐CD) was synthesized to obtain a spherical and spongy‐porous texture with a broad pore size distribution. The MIP(MAA‐β‐CD) showed fast kinetic and the intra‐particle diffusion model demonstrated a three step (surface and pore) adsorption process. The Koble‐Corrigan isotherm was the most suitable model for data fitting, which indicated that MIP(MAA‐β‐CD) had homogeneous and heterogeneous surfaces. This finding clearly demonstrated that the large uptake and strong affinity of MIP(MAA‐β‐CD) did not only probably result from the monomer‐template interactions, but also due to the morphological MIP(MAA‐β‐CD) structure. In contrary to MIP(MAA‐β‐CD), MIP(MAA) synthesized with uniform morphology and narrow pore size distribution had lower adsorption capacities and its kinetic data fitted the pseudo‐second order diffusion model, indicating a two‐step (surface only) adsorption process. The MIP(MAA) adsorption process followed the Langmuir isotherm model referred to solely homogeneous uptake. The calculated thermodynamic parameters showed that the BzP uptake was exothermic, spontaneous, and physisorption process onto MIPs, which supported the results of kinetics and isotherm adsorption data. This study clearly revealed that the presence of β‐CD improved the morphology of synthesized MIP, and automatically enhanced the adsorption behavior of MIP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42720.     

酪素胶束结构及其纳米功能化的研究进展

总结了国内外关于酪素胶束微观结构及其胶束结构表征手段的研究,重点阐述了纳米粒子改性酪素胶束结构以获得功能材料的研究进展,希望对从事酪素研究的工作者有所帮助。