Isothermal crystallization kinetics and melting behavior of multiwalled carbon nanotubes/polyamide‐6 composites

Pristine and functionalized multiwalled carbon nanotubes (MWNTs) were used to fabricate polyamide 6 (PA6) composites through melt blending. The functionalized MWNTs were obtained by grafting 1,6‐hexamethylenediamine (HMD) onto the pristine MWNTs to improve their compatibility with PA6 matrix. The effect of MWNTs on the isothermal crystallization and melting behavior of PA6 was investigated by differential scanning calorimetry (DSC) and X‐ray diffraction (XRD). The Avrami and Lauritzen–Hoffmann equations are used to describe the isothermal crystallization kinetics. The values of the Avrami exponent found for neat PA6, the pristine MWNTs/PA6 and functionalized MWNTs/PA6 composite samples are about 4.0, 1.7, and 2.3, respectively. The activation energies are determined by the Arrhenius method, which is lower for the composites, ?320.52 KJ/mol for pristine MWNTs/PA6 and ?293.83 KJ/mol for functionalized MWNTs/PA6, than that for the neat PA6 (?284.71 KJ/mol). The following melting behavior reveals that all the isothermally crystallized samples exhibit triple melting endotherms at lower crystallization temperature and double melting endotherms at higher crystallization temperature. The multiple melting endotherms are mainly caused by the recrystallization of PA6 during heating. The resulting equilibrium melting temperature is lower for the composites than for neat PA6. In addition, polarizing microscopy (PLM) and small angle light scanning (SALS) were used to study the spherulite morphology. The results show that the MWNTs reduce the spherulite radius of PA6. This reduction is more significant for pristine MWNTs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Polymer electrolytes based on poly(ethylene glycol) and cyanoresin

Polymer electrolytes based on a mixed polymer matrix consisting of poly(ethylene glycol) (PEG) and cyanoresins with lithium salt and plasticizer were prepared with an in situ blending process to improve both the mechanical properties and the ionic conductivity (σ). The PEG/lithium perchlorate (LiClO₄) complexes, including blends of cyanoethyl pullulan (CRS) and cyanoethyl poly(vinyl alcohol) (CRV), exhibited higher σ's than a simple PEG/LiClO₄ complex when the blend compositions of CRS/CRV were 5 : 5 or 3 : 7 or than CRV alone. When the CRS/CRV blend was compared with a copolymer of cyanoethyl pullulan and cyanoethyl poly(vinyl alcohol) (CRM) in the same molar ratio, the σ values of the polymer electrolytes containing the CRM copolymer series were slightly higher than those of the CRS/CRV blends containing PEG/LiClO₄ complexes. Moreover, the addition of cyanoresin to PEG/LiClO₄/(ethylene carbonate–propylene carbonate) polymer electrolytes provided better thermal stability and dynamic mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2402–2408, 2007     

Competitive adsorption of uranyl ions in the presence of Pb(II) and Cd(II) ions by poly(glycidyl methacrylate) microbeads carrying amidoxime groups and polarographic determination

The adsorption capacity of UO in the presence of Pb(II) and Cd(II) ions was investigated with amidoximated poly(glycidyl methacrylate) (PGMA) microbeads with an average size of 135 μm packed in a glass column (0.5‐cm i.d. and 20‐cm length, flow rate = 3 mL/min) under competitive conditions. A differential pulse polarography technique was used for the determination of trace quantities of uptaken elements by the measurement of the reduction peak currents at ?200/?950, ?400, and ?600 mV (vs a saturated calomel electrode) for UO, Pb(II), and Cd(II) ions, respectively. When only UO was found in the eluate, its adsorption was 85.3% from a 50 μM initial solution. However, when there was UO with binary systems of Pb(II) or Cd(II), it was 78.2 and 76.3%, respectively. On the other hand, in a ternary mixture of UO with Pb(II) and Cd(II), the adsorption was found to be 75.2% with the same initial concentration. According to the results, the competitive adsorption studies showed that these amidoximated PGMA microbeads had good adsorption selectivity for UO with the coexistence of Pb(II) and Cd(II) ions. The ionic strength of the solution also influenced the UO adsorption capacity of the amidoximated PGMA microbeads. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4168–4172, 2007     

Molecularly imprinted polymers for the selective recognition of l‐phenylalanine based on 1‐buty‐3‐methylimidazolium ionic liquid

To enhance the affinity of 4‐vinyl pyridine to l ‐phenylalanine (l ‐Phe) and convert the imprinting process from the aqueous phase to the organic phase, an oil‐soluble amino acid ionic liquid was introduced as a template. In this study, 1‐butyl‐3‐methylimidazolium α‐aminohydrocinnamic acid salt was first applied to prepared surface molecularly imprinted polymers (MIPs) in acetonitrile for the selective recognition of l ‐Phe. Fluorescence quenching analysis of the functional monomer on the template was investigated under different conditions to study the imprinting mechanism. Several binding studies, such as the sorption kinetics, sorption thermodynamics, and solid‐phase extraction application, and the chiral resolution of racemic phenylalanine were investigated. The binding isotherms were fitted by nonlinear regression to the Freundlich model to investigate the recognition mechanism. The affinity distribution analysis revealed that polymers imprinted by ionic liquid showed higher homogeneous binding sites than those imprinted by l ‐Phe. The competition tests were conducted by a molecularly imprinting solid‐phase extraction procedure to estimate the selective separation properties of the MIPs for l ‐Phe. The target MIP was shown to be successfully for the separation of l ‐Phe from an amino acid mixture. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42485.     

Thermoresponsive hollow magnetic microspheres with hyperthermia and controlled release properties

Thermoresponsive hollow magnetic microspheres consisting of a hollow magnetic core, a carbon shell, and a smart polymer layer are presented in this article. A carbon nanomaterial was used as a steric stabilizer for Fe₃O₄ nanoparticles and a supporter for polymer. The thermoresponsive monomer, N‐isopropyl acrylamide, was grafted on the carbon‐encapsulate hollows by surface radical polymerization. The experimental results indicate that the composites had a phase‐transition temperature around 43°C and a saturation magnetization of 56.9 emu/g; this showed apparent thermosensitivity and magnetism. The performances in hyperthermia evaluated by an inductive magnetic field showed that the hybrid microspheres had a specific absorption rate of 240 W/g. The model drug, 5‐fluorouracil, was loaded in and released from the microspheres with different release rates at 35 and 50°C. This demonstrated that the as‐synthesized microspheres had a thermotriggered release ability and would be a good drug carrier in the biomedical field. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42617.     

Emulsifier‐free cationic latexes based on vinylbenzyl chloride and 2‐(dimethylamino)ethyl methacrylate with adjusted hydrophilic–hydrophobic properties

Functional emulsifier‐free cationic latexes based on styrenic monomer vinylbenzyl chloride (VBC) and acrylic monomer 2‐(dimethylamino)ethyl methacrylate (DMA) were successfully prepared with dual quaternary ammonium ions (36–63 mol %) on both monomer moieties in two‐stages. First, [2‐(methacryloyloxy)ethyl]dimethylhexadecylammonium bromide monomer (DMA(C₁₆)), prepared via quaternization of DMA with 1‐bromohexadecane, was utilized as a comonomer (5–20%) as well as a surfactant in the emulsion polymerization of VBC. Next, the quaternization of chloromethyl groups in the VBC moiety in latex particles with trimethylamine and N,N‐dimethylhexadecylamine created a second type of quaternized sites on the latex particles. The percentages of the quaternary ammonium ions of the first‐stage latexes (P[VBC‐DMA(C₁₆‐x)]) and the second‐stage latexes (P[VBC(R)‐DMA(C₁₆‐x)]) were determined using bromide and chloride ion‐selective electrodes. The particles were characterized with a scanning electron microscope, Zetasizer, measuring water contact angles of their pellets. The polymer structure and the alkyl group length in their quaternary ammonium ions played an important role on the sizes, zeta potentials and hydrophilic–hydrophobic balances of the latexes. The water contact angles of the pellets of the latex particles varied from 50.3 to 109.6° depending on both the polymer structure and the alkyl group length. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42775.     

Synthesis and characterization of a surface imprinting silica gel polymer functionalized with phosphonic acid groups for selective adsorption of Fe(III) from aqueous solution

A Fe(III) ion‐imprinted silica gel polymer functionalized with phosphonic acid groups (IIP‐PA/SiO₂) was prepared with surface imprinting technique by using Fe(III) ion as template ion, grafted silica gel as support, and vinylphosphonic acid as functional monomer. The polymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller, and thermogravimetric analysis. The synthesized imprinted silica gel polymer was used as a sorbent for Fe(III) adsorption. The adsorption properties, such as the effect of solution pH, adsorption kinetic, adsorption isotherm, adsorption selectivity as well as the regeneration of sorbent were studied. The results showd that the prepared sorbent (IIP‐PA/SiO₂) had a short adsorption equilibrium time (12 min) and high adsorption capacity (29.92 mg g^?1) for Fe(III) at the optimal pH of 2.0. The selectivity coefficients of the sorbent for Fe(III) in presence of Cr(III), M_n (II), and Zn(II) were 51.76, 27.86, and 207. 76, respectively. Moreover, the adsorption capacity of the prepared sorbent did not decrease significantly after six repeated use. Thus, the prepared ion‐imprinted silica gel polymer was a promising candidate sorbent for the selective adsorption of Fe(III) from aqueous solutions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45165.     

聚烯烃热塑性弹性体官能化的方法及其应用

介绍了聚烯烃热塑性弹性体(POE)官能化-熔融接枝的几种方法:在有机过氧化物引发剂存在下的熔融接枝法,裂解引发接枝,机械力引发接枝,复合引发接枝等,POE官能化接枝能改善其与极性的聚物间的界面亲和性,提高共混物的相容性、冲击强度和韧性等,从而拓宽POE的应用领域。     

Aqueous polyacrylate/poly(silicone‐co‐acrylate) emulsion coated fertilizers for slow nutrient‐release application

Waterborne polyacrylate/poly(silicone‐co‐acrylate) emulsions were synthesized to develop coated fertilizers. The effects of the n‐butyl acrylate (BA)/methyl methacrylate (MMA) ratio, vinyltriethoxysilane, and synthesis method on the water resistance, glass‐transition temperature, mechanical properties, and nutrient‐release profiles were investigated. The results show that miniemulsion polymerization with a BA/MMA ratio of 55:45 was the most suitable for slow nutrient‐release applications. Under these conditions, the preliminary solubility rate of the nutrient was about 3%, and the 30‐day cumulative nutrient release was 15% at 25°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40369.     

Cotton‐fabric‐grafted poly(N‐isopropyl acrylamide) initiated by ammonium peroxydisulfate

In this article, we report that thermoresponsive poly(N‐isopropyl acrylamide) (PNIPAAm) was successfully grafted onto a cotton fabric (CF) surface by free‐radical solution grafting polymerization; we obtained a thermoresponsive CF‐grafted PNIPAAm. This reaction system only contained four constituents: the monomer, solvent, initiator, and CFs. Ammonium peroxydisulfate was chosen as the initiator, and water was chosen as the solvent. A series of initiator concentrations and grafting polymerization temperatures were used in the experiments, and their effects on the grafting ratio (G) were also studied. Also, the effects of the G of CF‐g‐PNIPAAm on their corresponding thermoresponses was studied further. The structure of CF‐g‐PNIPAAm was characterized by Fourier transform infrared spectroscopy–attenuated total reflectance analysis and scanning electron microscopy analysis. The G of CF‐g‐PNIPAAm was measured by a gravimetric method. The thermoresponse of CF‐g‐PNIPAAm was characterized by modulated differential scanning calorimetry, water contact angle measurements, and wetting time measurements. The experiments manifested the following results: (1) the initiator concentration and grafting polymerization temperature both influenced G, (2) the grafted PNIPAAm covered the CF surface, (3) the CF‐g‐PNIPAAm showed thermoresponsive hydrophilicity/hydrophobicity, and (4) a relationship existed between the thermoresponse of CF‐g‐PNIPAAm and the corresponding G. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41193.