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The two-dimensional (2D) assembly of gold nanoparticles (AuNPs) in a confined geometry is a rare phenomenon that has not been experimentally verified for complex systems. In this study, this process was investigated in detail using two types of block copolymers with hydrophobic and hydrophilic blocks and a series of AuNPs of three different sizes protected by hydrophobic ligands. In aqueous solutions, the selected block copolymers self-assembled into vesicular nanostructures with a hydrophobic domain in the wall, which functions as a confined geometrical space for hydrophobic AuNPs (i.e., it exerts a confinement effect and restricts the movement of AuNPs). Small-angle X-ray scattering studies revealed that AuNPs of different sizes assembled differently in the same confined geometry of the vesicular wall. In addition, optimal conditions for the formation of a regular NP array in the hydrophobic domain were determined. The AuNPs successfully self-assembled into a regular 2D lattice structure, forming a shell around the vesicle, when their size matched the thickness of the hydrophobic domain of the vesicular nanostructure. This study provides guidelines for the fabrication of nanoparticle arrays with controlled structures, which could enhance the functionality of materials and their physical properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • NiFe PB-alginate hydrogel (NiFe-AH) was synthesized by cross-linking with Ni2+. • The Cs+ adsorption of NiFe-AH increased by 1.5 times during light irradiation. • NiFe-AH exhibited higher Cs+ adsorption than commercialized AMP-PAN and KNiFe-PAN. • Weight and volume of NiFe-AH could be drastically reduced after Cs+ adsorption. • The mechanism of photoinduced enhancement of Cs+ adsorption by NiFe-AH was proved. Prussian blue analogues are promising materials for 137Cs removal; however, their use is limited by the challenge of separating them from an aqueous solution after 137Cs adsorption. This study synthesized a NiFe embedded alginate hydrogel (NiFe-AH) via cross-linking with Ni2+. The prepared NiFe-AH exhibited an excellent performance for Cs+ adsorption. The adsorption capacity of NiFe-AH under UV (0.891 mmol/g) or visible light irradiation (0.885 mmol/g) increased approximately 1.5 times more than before light irradiation (0.591 mmol/g). Moreover, the volume and weight of NiFe-AH after Cs+ adsorption decreased substantially, showing advantage in radioactive nuclide disposal. NiFe-AH exhibited high Cs+ adsorption capacity in all pH ranges, even in the presence of competing ions such as Na+, K+, Ca2+, and Mg2+. Compared to commercialized Cs+ adsorbents (AMP-PAN and KNiFe-PAN), NiFe-AH proved to have a greater Cs+ adsorption capacity. Analyses using XPS and XANES indicated that the photoinduced enhancement mechanism of Cs+ adsorption on NiFe-AH was attributed to NiFe absorbing the light, resulting in the reduction of Fe(III) to Fe(II) within NiFe. Accordingly, Cs+ ions were additionally adsorbed on NiFe. The NiFe-AH showed exceptional 137Cs removal in seawater, suggesting that it has strong potential as a practical adsorbent. [ABSTRACT FROM AUTHOR]

Pluronic amphiphilic block copolymers, well known to have a phase behavior can be controlled by external conditions, have a wide range of potential for applications such as nanotemplates or nanobuilding blocks. However, the phase behaviors of Pluronic block copolymer/additive complexes with highly ordered phases have not been fully investigated. Here, we report the unusual molecular weight-dependent self-assembly of Pluronic block copolymer/additive complexes. Depending on the temperature and additive, Pluronic P65 block copolymer with a lower molecular weight showed the closed loop-like (CLL) phase behavior with the disorder-order-disorder-order phase transition in aqueous solution, whereas Pluronic P105 and P85 block copolymers with higher molecular weights underwent highly ordered continuous phase transitions with face centered cubic (FCC), hexagonal, and lamellar phases. It is expected that the specific phase behavior of the block copolymer/additive complex can be applied in optical devices such as nanotemplates or optical sensors for a highly ordered superlattice. Furthermore, this study provides a new route to control the phase behavior of the block copolymers without a complicated process. [ABSTRACT FROM AUTHOR]

A self-assembled unilamellar vesicle, which can be used as a drug delivery system, was easily and simply fabricated using a blended system of Pluronic block copolymers. Controlling the hydrophilic mass fraction of block copolymers (by blending the block copolymer with a different hydrophilic mass fraction) and temperature (i.e., the hydrophobic interaction is controlled), a vesicular structure was formed. Small angle neutron scattering measurements showed that the vesicular structure had diameters of empty cores from 13.6 nm to 79.6 nm, and thicknesses of the bilayers from 2.2 nm to 8.7 nm when the hydrophobic interaction was changed. Therefore, considering that the temperature of the vesicle formation is controllable by the concentration of the blended block copolymers, it is possible for them to be applied in a wide range of potential applications, for example, as nanoreactors and nanovehicles. [ABSTRACT FROM AUTHOR]

Abstract A new method to easily derive the phase transition of amphiphilic block copolymer in aqueous solution is suggested in this study. Using two kinds of Pluronic triblock copolymers, which have different mass fractions of the hydrophilic part of the block copolymer, the mixed block copolymers in aqueous solution self-assembled into a variety of nanostructures. Small angle neutron scattering revealed that the block copolymer complex formed spheres, cylinders, and vesicles depending on both the concentration of another Pluronic block copolymer (Pluronic PE6200) as an additive and temperature. This phase behavior can be easily explained in terms of the hydrophobicity of the block copolymer by increasing its effective hydrophobic moiety and temperature. [ABSTRACT FROM AUTHOR]

Acid mine drainage sludge (AMDS) is a solid waste generated following the neutralization of acid mine drainage (AMD). This material entrapped in calcium alginate was investigated for the sorption of As(III) and As(V). Three different adsorbent materials were prepared: AMDS alginate beads (AABs), goethite alginate beads (GABs), and pure alginate beads. The effects of pH and the adsorption kinetics were investigated, and the adsorption isotherms were also evaluated. The optimum pH range using the AABs was determined to be within 2–10 for As(III) and 2–9 for As(V). Adsorption equilibrium data were evaluated using the Langmuir isotherm model, and the maximum adsorption capacity q max was 18.25 and 4.97 mg g −1 for As(III) on AAB and GAB, respectively, and 21.79 and 10.92 mg g −1 for As(V) on AAB and GAB, respectively. The adsorption of As(III) and As(V) was observed to follow pseudo-second order kinetics. The As K-edge X-ray absorption near-edge structure (XANES) revealed that the adsorbed As(III) on the AABs was oxidized to As(V) via manganese oxide in the AMDS. [ABSTRACT FROM AUTHOR]

The tacticity effect on phase separationprocess of poly(N-isopropylacrylamide) (PNiPAM) aqueoussolutions was investigatedby dynamic light scattering (DLS) and small angle neutron scattering(SANS) measurements. SANS measurement revealed that hydrophobicityof PNiPAM consisting of meso- and racemo-isomers increased with increasingthe meso-content. This result is in accordance with the result ofthe previous experimental and simulation study on NiPAM dimers (DNiPAM)and trimers (TNiPAM) [Katsumoto, Y.; J. Phys. Chem. B2010, 114, 13312−13318, and Autieri, E.; J. Phys. Chem. B2011, 115, 5827–5839]; i.e., meso-diad is more hydrophobic than racemo-diad.In addition, a series of scattering experiments revealed that theratio of meso-diad does not affect the static structure or the shrinkingbehavior of a single chain, but strongly affects the aggregation behavior.The PNiPAMs with low meso-content suddenly associate around the phaseseparation temperature, while that of the high meso-content graduallyaggregate with increasing temperature. We propose that phase transitionbehavior of PNiPAM aqueous solutions can be controlled by changingthe stereoregularity of the polymer chain. [ABSTRACT FROM AUTHOR]