Electrical Properties of Carboxyl Methylcellulose/Chitosan Dual-Blend Green Polymer Doped with Ammonium Bromide

This present work discusses dual-blend green polymer electrolyte (GPE)–based natural polymers, composed of carboxyl methylcellulose (CMC) and chitosan (CS), created by introducing various compositions of ammonium bromide (NH₄Br) as a dopant in the system. These GPEs were successfully prepared by the solution casting technique and characterized using electrical impedance spectroscopy (EIS). From EIS measurement, the highest room-temperature conductivity is 1.21 × 10^?5 Scm^?1 for the sample containing 20 wt.% of NH₄Br. Plot of the temperature dependence of the GPEs revealed that the system obeys the Arrhenius rule and was thermally assisted. Besides that, dielectric studies were also conducted and the data were analyzed using complex permittivity, ?^*, and complex electrical modulus, M*, to determine the sample with the highest conductivity value. Thus, this study confirmed non-Debye behavior in the sample.     

Synthesis of a New Liquid Crystalline Polymer as a Highly Active β-Nucleator and Its Effect on Melting and Crystallization Behaviors of Isotactic Polypropylene

A new nematic liquid crystalline polymer as a highly active β-nucleator (LCP-N) of isotactic polypropylene (iPP) was synthesized and characterized. The effect of LCP-N on thermal behavior of the iPP was investigated with differential scanning calorimetry. LCP-N showed a melting transition at 85.0°C and a nematic to isotropic phase transition at 278.0°C. The incorporation of LCP-N could lead to substantial changes in the thermal behavior of the iPP. The nucleating activity of LCP-N mainly depended on its content, mesogenic molecular structure, and thermal history of processing. A high content of β-form could be obtained by the combined effect of the optimum LCP-N concentration and crystallization temperature and time. The Φ_β reached 77% when the LCP-N content, crystallization temperature, and crystallization time were 0.4 wt.%, 125°C, and 1 h, respectively.     

Polymeric Membranes Containing Phosphorus in the Chain for Solid Polymer Electrolytes

Abstract

Two new series of solid polymer electrolytes (SPEs) based on phosphorus containing (co)polyesters (PPE) and Lithium triflate were obtained. PPEs are composed of phosphonate moeties (cyclohexyldichlorophosphonate (CHDP)) as linking agent and two diols: PEG (6000) and poly(tetramethylene glycol) (PTMG) in PPE I, and PEG (6000) and 4,4′-cyclohexylidenebisphenol (bisphenol Z, BZ) in PPE II. Polycondensation was carried out in solution in the presence of triethylamine (TEA) as scavenger of HCl side product (PPE I–IIa) and in the absence of any acid acceptor (PPE I–IIb). The Limiting Oxygen Index (LOI) and thermal analysis were performed both on polymers and membranes. The ionic conductivity of SPE membranes based on PPE-salt complexes, with various salt concentrations, was investigated at different temperature and ionic transference numbers were determined. Optimum composition was obtained for the polymer which contains in structure only alkyl units and 15% Lithium triflate.     

Design and synthesis of pyromellitic diimide‐based donor–acceptor conjugated polymers for photovoltaic application

Three of conjugated polymers based on pyromellitic diimide (PMDI) as the acceptor unit and thienothiophene (TT) as the donor unit were successfully synthesized by Stille coupling. The effect of the side chain length and thiophene π‐bridge on the polymers' optical and electrochemical properties was investigated. Electrochemical characterization indicated that these polymers have deep highest occupied molecular orbital energy levels between ?5.7 and ?5.8 eV. Polymer solar cells were fabricated by using these PMDI‐based polymers as the donor and [6,6]‐phenyl‐C61‐butyric acid methyl ester as the acceptor. The polymer P1 whose PMDI unit was functionalized with 2‐ethylhexyl side chain shows the higher short‐circuit current (J_sc) and fill factor (FF) compared with that of P2 with a 2‐octyldodecyl side chain on the PMDI unit. The results also illustrate that the insertion of a thiophene π‐bridge between PMDI and TT (the polymer P3) leads to the broader absorption and better photovoltaic performance. The best performance was obtained from the cell based on the polymer P3 with a power conversion efficiency of 0.43% under the illumination of AM 1.5 G, 100 mW/cm². Copyright © 2014 John Wiley & Sons, Ltd.     

Recycling ground tire rubber (GTR) scraps as high‐impact filler of in situ produced polyketone matrix

A sustainable procedure for recycling powdered rubber coming from scrap tires (ground tire rubber [GTR]) is proposed as based on the dispersion in polyketone (PK) matrix, obtained in situ by CO/ethylene copolymerization. Three types of catalysts are used operative in solvents of different polarities. The catalyst productivity and the hybrids morphology are evaluated and optimized to final composites features. The obtained products are characterized by scanning electron microscopy, atomic force microscopy, and solvent extractions in order to investigate the occurrence and the extent of interactions between PK macromolecular chains and the GTR components; and their effects on the final properties were tested by differential scanning calorimetry, thermogravimetric analysis, and rheological measurements. For comparison purpose, a composite with GTR included into the matrix through blending is prepared. The results evidenced the key role exerted by the catalyst that, when operative in apolar solvent (able to swell the rubber phase), provides composites with good interfacial adhesion and breaking up of the particles with beneficial effects on final properties particularly thermal features and processability. Copyright © 2014 John Wiley & Sons, Ltd.     

Super‐fast oil uptake using porous ultra‐high molecular weight polyethylene sheets

This paper presents the oil uptake of porous sorbent polymer sheets consisting of ultra‐high molecular weight polyethylene. A comprehensive set of experiments are performed showing the saturation contact time, retention value, mechanical properties, oil pick‐up ratio, pick‐up density, and dynamic dripping profile. Kinetic modeling of the oil sorption is also provided. The experimental results show a good correlation with the pseudo‐second order model. The sheets exhibit high oil uptake speeds, requiring less than 2 min in contact with the oil to reach saturation. The sheets fulfill the criteria of high uptake kinetics, high sorption capacity, and high mechanical strength simultaneously. Those characteristics enable their use in practical spill response. Copyright © 2014 John Wiley & Sons, Ltd.     

Phenylboronate‐diol crosslinked polymer/SWCNT hybrid gels with reversible sol–gel transition

This work demonstrates the successful incorporation of functionalized single‐walled carbon nanotubes (f‐SWCNTs) into the phenylboronate‐diol crosslinked polymer gel to create a hybrid system with reversible sol–gel transition. The phenylboronic acid‐containing and diol‐containing polymers were first separately prepared by the reversible addition–fragmentation chain transfer polymerization. Covalent functionalization of single‐walled carbon nanotubes (SWCNTs) with an azide‐derivatized, diol‐containing polymer was then accomplished by a nitrene addition reaction. Subsequently, the hybrid gels were prepared by crosslinking the mixture of f‐SWCNTs and diol‐containing polymer with the phenylboronic acid‐containing polymer. The hybrid gel has been characterized by scanning electron microscopy (SEM) and rheological analysis. The SEM measurement demonstrated a homogeneous dispersion of f‐SWCNTs within the gel matrices. Rheological experiments also demonstrated that the hybrid gel exhibited storage moduli significantly higher than those of the native gel obtained from the phenylboronic acid‐containing and diol‐containing polymers. The hybrid gel can be switched into their starting polymer (f‐SWCNTs) solutions by adjusting the pH of the system. Moreover, the hybrid gel revealed a self‐healing property that occurred autonomously without any outside intervention. By employing this dynamic character, it is possible to regenerate the used gel, and thus, it has the potential to perform in a range of dynamic or bioresponsive applications Copyright © 2013 John Wiley & Sons, Ltd.     

Electropolymerized coatings of poly(o‐anisidine) and poly(o‐anisidine)‐TiO2 nanocomposite on aluminum alloy 3004 by using the galvanostatic method and their corrosion protection performance

Poly(o‐anisidine) (POA) and poly(o‐anisidine)‐TiO₂ (POA‐TiO₂) nanocomposite coatings on aluminum alloy 3004 (AA3004) have been investigated by using the galvanostatic method. The electrosynthesized coatings were characterized by FT ‐ IR spectroscopy, XRD, SEM ‐ EDX and SEM. The corrosion protection performance of POA and POA‐TiO₂ nanocomposite coatings was investigated in the 3.5% NaCl solution by using potentiodynamic polarization technique and electrochemical impedance spectroscopy. The results show that the corrosion rate of the nanocomposite coatings is about 900 times lower than the bare AA3004 under optimal conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Antimicrobial silica particles loaded with quaternary ammonium polyethyleneimine network

Silica particles functionalized with quaternary ammonium groups were prepared by interpenetrating polyethylenimine (PEI) into silica particles and crosslinking with diiodopentane, followed by octyliodide alkylation and methyliodide quaternarization (S‐QA‐PEI). The synthesized S‐QA‐PEI particles were identified with a slight particle size increase of 2–3 µm. Different ratios of PEI:silica particles were prepared and analyzed. While silica particles are negatively charged, ?16.7 ± 5.11 mV, the prepared S‐QA‐PEI particles are positively charged, +50–60 mV. These particles were embedded in poly(ethylene vinyl acetate) and poly(ethylene methacrylic acid) coatings which exhibited strong antibacterial activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Performance Enhancement of Bulk Heterojunction Solar Cells with Direct Growth of CdS‐Cluster‐Decorated Graphene Nanosheets

Two‐dimensional graphene–CdS (G–CdS) semiconductor hybrid nanosheets were synthesized in situ by graphene oxide (GO) quantum wells and a metal–xanthate precursor through a one‐step growth process. Incorporation of G–CdS nanosheets into a photoactive film consisting of poly[4,8‐bis‐(2‐ethyl‐hexyl‐thiophene‐5‐yl)‐benzo[1,2‐b:4,5‐b]dithiophene‐2,6‐diyl]‐alt‐[2‐(2‐ethyl‐hexanoyl)‐thieno[3,4‐b]thiophen‐4,6‐diyl] (PBDTTT‐C‐T) and [6,6]‐phenyl C₇₀ butyric acid methyl ester (PC₇₀BM) effectively decreases the exciton lifetime to accelerate exciton dissociation. More importantly, the decreasing energy levels of PBDTTT‐C‐T, PC₇₀BM, and G–CdS produces versatile heterojunction interfaces of PBDTTT‐C‐T:PC₇₀BM, PBDTTT‐C‐T:G–CdS, and PBDTTT‐C‐T:PC₇₀BM:G–CdS; this offers multi‐charge‐transfer channels for more efficient charge separation and transfer. The charge transfer in the blend film also depends on the G–CdS nanosheet loadings. In addition, G–CdS nanosheets improve light utilization and charge mobility in the photoactive layer. As a result, by incorporation of G–CdS nanosheets into the active layer, the power‐conversion efficiency of inverted solar cells based on PBDTTT‐C‐T and PC₇₁BM is improved from 6.0 % for a reference device without G–CdS nanosheets to 7.5 % for the device with 1.5wt % G–CdS nanosheets, due to the dramatically enhanced short‐circuit current. Combined with the advantageous mechanical properties of the PBDTTT‐C‐T:PC₇₀BM:G–CdS active layer, the novel CdS‐cluster‐decorated graphene hybrid nanomaterials provide a promising approach to improve the device performance.