The effect of tunable modification parameters on the structure and properties of polypropylene with cyclotrimerization surface of isocyanates

The cyclotrimerization of methylene diphenyl 4,4‐diisocyanate (MDI) and 3‐isopropenyl‐α,α′‐dimethylbenzene isocyanate (TMI) was applied on the bead/membrane surfaces of a polypropylene (PP)‐bearing isocyanate group to synthesize a protective networked polymer. Chemical structures of these molecules were characterized through attenuated total reflectance–Fourier transform infrared spectroscopy. Results showed that the absorption peak of isocyanate group at 2255 cm^?1 became negligible after the reaction was completed. The absorption peaks of the isocyanurate groups appeared simultaneously at 1600 cm^?1 and at 1510–1560 cm^?1; this result indicated that the grafted isocyanates were almost consumed, thereby forming isocyanurates. Energy X‐ray dispersive spectroscopy revealed that oxygen content increased; indeed, isocyanurate was formed on the PP surface. Pure PP beads, PP‐g‐TMI, and cyclotrimerization products were also subjected to thermal property tests to investigate their corresponding thermal stabilities. Cyclotrimerization could result in the increase in PP‐grafted decomposition temperature, even slightly higher than pure PP. Rheological behavior in oscillatory flow was also evaluated; the storage modulus, loss modulus, and complex viscosity of cyclotrimerization products were higher than those of the PP‐grafted membranes. Surface morphology was further observed through field‐emission scanning electron microscopy and atomic force microscopy. The cyclotrimerization products contained blocks and exhibited a rough surface. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43327.     

Quaternized poly(phenylene oxide) anion exchange membrane for alkaline direct methanol fuel cells in KOH‐free media

A series of anion exchange membrane (AEM) electrolytes with quaternary ammonium moiety are fabricated from poly (phenylene oxide) for its application in alkaline direct methanol fuel cells (ADMFCs). In the first step, poly(phenylene oxide) (PPO) is successfully chloromethylated by substituting chloromethyl groups in the aryl position of polymer. In the second step, the chloromethylated PPO (CPPO) is further homogeneously quaternized and ion‐exchanged to form an AEM. From the second step, series of AEMs are prepared by changing the mole ratio of amine in relation to CPPO. The presence of quaternary ammonium group in the membrane was confirmed by elemental analysis. The fabricated membranes are subjected to cell polarization studies in ADMFCs, wherein quaternized poly(2,6‐dimethyl‐1,4‐phenylene oxide) (CPPO:amine of 1:8) membrane exhibits higher peak power density of 3.5 mW cm^?2 when compared with the other ratios of CPPO:amine in the absence of KOH solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43693.     

POSS‐based fluorinated azobenzene‐containing polymers: Photo‐responsive behavior and evaluation of water repellency

The photoresponsive polyhedral oligomeric silsesquioxanes (POSS) based fluorinated azobenzene‐containing polymers were prepared and characterized by NMR, FT‐IR, GPC, XRD, TG and UV–Vis spectra. The thermal property of the polymers was improved by the introduction of POSS cage. The trans‐cis photoisomerization of the polymers in solution was similar to that of the fluorinated azobenzene monomer and in accordance with the first‐order reaction kinetics equation within the first 250 seconds UV irradiation. The cotton fabrics coated with the polymers showed excellent water repellency and possessed switchable wettability under UV irradiation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43540.     

Method for the synthesis of para‐aramid nanofibers

The synthesis and electrospinning of novel N‐substituted aramid nanofibers (ANFs) prepared from basic dispersions of commercial microscale Kevlar fibers are herein reported. The functionalized ANFs were characterized via Fourier transform infrared spectroscopy, ¹³C solid‐state nuclear magnetic resonance spectroscopy, and X‐ray diffraction to confirm proper N‐substitution of the side groups and to determine changes to the polymer crystallinity and stability. These analyses suggested that the electrospun ANFs consisted of numerous crystalline domains in the transverse fiber direction with large amorphous regions that were void of defects commonly found in commercial Kevlar fibers. A semi‐empirical study of the variations in the solubility parameter due to various side chain moieties was conducted to facilitate solvent selection and to elucidate the enhanced solubility effects with selected organic solvents. These initial findings suggest a promising route for obtaining a new class of nanofibers with ultrahigh strength and stiffness. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44082.     

Specific heavy metal ion recovery with ion‐imprinted cryogels

In this study, the functional monomers, N‐methacryloyl‐l ‐aspartic acid and N‐methacryloyl‐l ‐cysteine were synthesized through a reaction between appropriate amino acids and methacryloyl chloride. Then, Pb(II) or Cd(II) ion‐imprinted 2‐hydroxyethyl methacrylate based cryogels were prepared by free radical polymerization method under partially frozen conditions. Following the characterization of matrices, adsorption of heavy metal ions was examined in batch mode from aqueous solution considering several parameters affecting the adsorption performance. The actual adsorption capacities were 44.5, 65.3, and 86.7 mg/g for Cd‐1, Cd‐2, and Cd‐3 cryogels meanwhile those were 41.9, 86.3, and 122.7 mg/g for Pb‐1, Pb‐2, and Pb‐3 cryogels, respectively at optimum pH: 5.5. By increasing temperature, adsorption capabilities of both cryogels were inhibited because of the electrostatic nature of coordinated covalent bonds and collapsing of coordination spheres. The adsorption process was very fast, the equilibrium adsorption was achieved in about 60 min, which was directly related to macroporous structure and interconnected flow‐channels of cryogels. Kinetics and adsorption isotherms were also studied. Langmuir isotherms and pseudo‐second order kinetic model were well suited to adsorption data, which also indicated that the process occurred without any diffusion restrictions or steric hindrances. Finally, the competitive adsorption studies were performed using multi‐ion containing synthetic wastewater to show whether the cryogels developed are suitable for specific heavy metal recycling or not. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43095.     

Montmorillonite as support for peroxide in the melt grafting of maleic anhydride onto polypropylene

Grafting of maleic anhydride onto polypropylene was performed in a Haake torque rheometer, in the presence of organically modified montmorillonite, MMT (used as support for the peroxide), according to a 2³ factorial design, where the maleic anhydride concentration (C_MA), peroxide concentration (C_per) and reaction time (t_r) were varied. For comparison, the reaction in the absence of MMT was also conducted. Polypropylene degradation was assessed by parallel plate rheometry and size exclusion chromatography (SEC) and percentage of reacted maleic anhydride (%MA_g) was obtained by titration and FTIR spectroscopy. The results showed differences in both systems, conventional and in the presence of MMT. The structure of polypropylene grafted with maleic anhydride, PP‐g‐MA, indicates longer branches are formed in the presence of MMT compared to in its absence, demonstrated by FTIR analysis. As in conventional reaction systems, an increase in C_per caused an increase in %MA_g and a reduction in molar mass. The variable C_MA showed to be not significant in the grafting reaction in the presence of MMT, even at high DCP levels, at a 5% significance level. On the other hand, increase in C_MA resulted in significant increase in viscosity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44134.     

Molecular dynamics simulations of molecularly imprinted polymer approaches to the preparation of selective materials to remove norfloxacin

A novel molecularly imprinted polymer (MIP) designed by molecular dynamics (MD) simulations was successfully prepared with norfloxacin as a template molecule, methyl acrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a crosslinker. According to the theoretical prediction and experimental preparation methods, three kinds of molecular imprinting materials were designed and synthesized with MD simulations and molecular imprinting technology. The best ratio of the template to the functional monomer to the crosslinker was 1:8:40 in these studies. The experimental results illustrate that the MD simulations were credible in compounding the components of the MIPs. The structure of the prepared polymers were characterized with various methods. To analyze the adsorption performances, many kinds of static adsorption tests, including kinetic, isotherm, and selectivity tests, were used. The results indicate that the novel adsorbents conformed to the pseudo–second‐order kinetic equation and followed the Langmuir isotherm model. The adsorption amounts of MIP2 at a ratio of 1:8:40 were about 29.35 mg/g at 298 K_. The selective adsorption and reusable performance of norfloxacin were excellent. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42817.     

The solution behavior of hydrophobically associating zwitterionic polymer in salt water

The acrylamide‐based hydrophobically associating zwitterionic polymer was prepared, which was composed of dimethyl‐dodecyl‐allyl ammonium chloride as hydrophobic group and carboxyl betaine 2‐(4‐acrylamido‐propyl‐dimethyl ammonic)‐sodium acetate as functional group. Hydrophobically associating polyacrylamide (HAPAM) was also prepared for comparative study. The behaviors of polymers in pure water and salt solutions were investigated by the means of apparent viscosity test, laser light scattering, atomic force microscope, and fluorescence experiments. The viscosities of polymer solution increased with the increasing of salt concentration, which indicated that the addition of salt resulted in significant antipolyelectrolyte effect in the zwitterionic polymer solution. The results of dynamic laser light scattering experiment also showed that the average hydrodynamic diameters of the zwitterionic polymer molecules increased with the increasing of salt concentration. The network structures had been observed by atomic force microscope and the addition of salt strengthened the formation of network structures. The results of fluorescence experiment showed that the addition of salt could enhance the association of hyrophobically zwitterionic polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39707.