Mesostructured ZnO/Au nanoparticle composites with enhanced photocatalytic activity

Publication date: 16 October 2017
Source:Polymer, Volume 128
Author(s): Carina Bojer, Judith Schöbel, Thomas Martin, Thomas Lunkenbein, Daniel R. Wagner, Andreas Greiner, Josef Breu, Holger Schmalz
Ease of catalyst separation from reaction mixtures represents a significant advantage in heterogeneous photocatalytic wastewater treatment. However, the activity of the catalyst strongly depends on its surface-to-volume ratio. Here, we present an approach based on cylindrical polybutadiene-block-poly(2-vinylpyridine) polymer brushes as template, which can be simultaneously loaded with zinc oxide (ZnO) and gold (Au) nanoparticles. Pyrolytic template removal of the polymer yields in mesostructured ZnO/Au composites, showing higher efficiencies in the photocatalytic degradation of ciprofloxacin and levofloxacin (generic antibiotics present in clinical wastewater) as compared to neat mesostructured ZnO. Upscaling of the presented catalyst is straightforward promising high technical relevance.

Graphical abstract

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Sulfonated polystyrene nanoparticles coated with conducting polyaniline and their electro-responsive suspension characteristics under electric fields

Publication date: 3 October 2017
Source:Polymer, Volume 127
Author(s): Shang Hao Piao, Chun Yan Gao, Hyoung Jin Choi
Core-shell structured conducting polyaniline (PANI)-coated polystyrene (PS) composite nanospherical particles were synthesized and assessed as a candidate for electrorheological (ER) materials. Monodisperse PS nanospheres were initially synthesized by a dispersion polymerization process and their surface was modified using concentrated sulfuric acid. This allowed the aniline monomer to be adsorbed easily on the sulfonated PS nanosphere and polymerized further by forming a PS/PANI nanosphere. The ER performance of their suspension dispersed in silicone oil was examined using a rotational rheometer under a variety of electric field strengths. The Bingham fluid model was used to analyze their flow curves to understand the interrelation between shear stress and shear rate. The relationship between the yield stress and electric field strength showed a slope of 2.0 following a polarization model. The dielectric spectra showed a good correlation with the ER performance of the ER fluid.

Graphical abstract

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[PCL-b-P(THF-co-CL)]m multiblock copolymer synthesized by Janus polymerization

Publication date: 16 October 2017
Source:Polymer, Volume 128
Author(s): Huan Qiu, Zhening Yang, Muhammad Ijaz Shah, Zhengwei Mao, Jun Ling
Multiblock copolymers (MBCPs) composing of poly(ε-caprolactone) (PCL) and poly(tetrahydrofuran-co-ε-caprolactone) (P(THF-co-CL)) segments are synthesized in a one-step process by "Janus polymerization", a newly raised synthetic protocol. Janus polymerization includes an anionic and a cationic ring-opening polymerization on both ends of a single living polymer chain, and finally couples into MBCPs. The well-defined MBCPs have relatively high molecular weights up to 131 kg/mol and exhibit thermoplastic elastic property with excellent elongation of 2610% in tensile tests. The repeating blocks form phase separation structures observed by AFM responsible for the elasticity. The biodegradable elastomers have negligible cytotoxicity. According to the physiochemical properties observed in this work, such multiblock elastic poly(ether-ester)s are promising materials in many fields.

Graphical abstract

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Organic dispersion of polyaniline and single-walled carbon nanotubes and polyblends with poly(methyl methacrylate)

Publication date: 27 October 2017
Source:Polymer, Volume 129
Author(s): Thomas Farrell, Kan Wang, Cheng-Wei Lin, Richard B. Kaner
Traditionally, in situ polymerization has been used to make polymer-carbon nanotube composites. Here, we report a simple method of mixing polyaniline with single-walled carbon nanotubes in a variety of organic solvents via ultrasonication. The maximum loading fraction of SWCNTs in the composites is determined by the conformation of the polyaniline chains. The type of solvent used has the greatest influence on the conformation of the polyaniline chains. Furthermore, the composites can be easily blended with poly(methyl methacrylate) (PMMA), to form polyblends. The electrical conductivities and transparencies of the polyblend films are reported.

Graphical abstract

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Porous lignin based poly (acrylic acid)/organo-montmorillonite nanocomposites: Swelling behaviors and rapid removal of Pb (II) ions

Publication date: 16 October 2017
Source:Polymer, Volume 128
Author(s): Yanli Ma, Ling Lv, Yuanru Guo, Yujie Fu, Qian Shao, Tingting Wu, Sijie Guo, Kai Sun, Xingkui Guo, Evan K. Wujcik, Zhanhu Guo
Lignin grafted N, N′-methylene-bisacrylamide (LM) was copolymerized with acrylic acid (AA) to fabricate lignin based poly (acrylic acid) (LBPAA) nanocomposites, and organo-montmorillonite (OrgMMT) was uniformly dispersed in LBPAA by ultrasonic method. The water absorbency in KCl solution was 302.9 g/g for LBPAA/OrgMMT (3 wt% OrgMMT, 43.65 wt% LM, and 53.35 wt% poly(acrylic acid) (PAA)), higher than PAA/OrgMMT (104.5736 g/g), and PAA (131.8 g/g). The Pb²⁺ adsorption for LBPAA/OrgMMT was demonstrated to be pH-dependent and followed Freundlich multilayer adsorption, with the removal following a pseudo-second-order kinetic model. The Pb²⁺ absorption capacity of LBPAA (PAA 48.50/48.50 LM)/OrgMMT (3 wt%) was 1.0803 mmol·g⁻¹, the highest among the composites. When the mole ratio of Na⁺ and Pb²⁺ was less than 0.21, the Pb²⁺ adsorption capacity of LBPAA/OrgMMT decreased slightly. The negative ΔG0 indicated that the Pb²⁺ adsorption process for composite hydrogel and PAA was spontaneous. XPS analysis data indicated that Pb²⁺ ions formed Pb-O bonds by hydroxyl groups and carboxyl groups for efficient lead ion adsorption. This study demonstrates that LBPAA/OrgMMT can be used as a water retention agent with salt tolerance and as an adsorbent for removing Pb²⁺ ions from industrial waste water.

Graphical abstract

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Necklace-shaped dimethylsiloxane polymers bearing polyhedral oligomeric silsesquioxane cages with alternating length chains

Publication date: 3 October 2017
Source:Polymer, Volume 127
Author(s): Naohiro Katsuta, Marie Yoshimatsu, Kunihiro Komori, Tsubasa Natsuaki, Kazuya Suwa, Kiyoshi Sakai, Takashi Matsuo, Tomoyuki Ohba, Shinobu Uemura, Satoshi Watanabe, Masashi Kunitake
Necklace-shaped dimethylsiloxane (DMS) polymers bearing polyhedral oligomeric silsesquioxane (POSS) cages with "alternating modulated chain" arrangements were synthesized, by the polycondensation of a dimeric POSS precursor and dimethyl oligo-siloxane dichloride. Films of POSS-DMS polymers with "alternating modulated chain" arrangements were highly transparent. This observation is consistent with amorphous structures. Along with "constant chain" and "random chain" type polymers, three different chain arrangements of necklace-shaped polymers can now be produced. The physical properties of the three polymer types with constant POSS cage contents were compared. "Alternating modulated chain" type polymers had lower glass transition temperatures than the other two polymer types. This was attributed to the cooperative relaxation of long chain moieties that comprised half of the connecting chains. "Alternating modulated chain" type POSS-DMS polymers with average chain lengths of three to four exhibited heat resistances of over 470 °C in air.

Graphical abstract

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Hierarchically porous silica composites via a colloidal reaction sequence

Publication date: 16 October 2017
Source:Polymer, Volume 128
Author(s): Ran Yu, Guoliang Li, Wei Huang, Klaus Tauer
A new class of polymeric colloids, multiple suspension particles (MSP), with a size of several micrometers consisting of many small polystyrene particles with a diameter below 100 nm grown in a poly (N-isopropyl acrylamide) precursor scaffold is obtained, as reported in our previous paper. Herein, the unique MSP are applied as template for silica nanocasting and hierarchically organized porous silica with raspberry-like aggregation structure is obtained. The aggregates with a diameter of about 1 μm are composed of thousands of hollow silica particles, which are with a size of about 70 nm originating from polystyrene particles and with mesopores of about 5.8 nm on the shell from PNIPAM chains. The aggregates have high specific surface area and pore volume. With the advantage of high mass transport contributed by macropores and of high specific surface area due to mesopores, the hierarchically organized structure has great potential application in catalysis field.

Graphical abstract

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