Well‐defined copolymers based on poly(vinylidene fluoride): From preparation and phase separation to application

Poly(vinylidene fluoride) (PVDF) has reached the second largest production volume of fluoropolymers in recent years, and its popularity can be ascribed to high thermal stability and chemical inertness combined with its ferroelectric behavior. Copolymerization of vinylidene fluoride with other monomers leads to a wide variety of products with modified or improved properties. Besides commercially available fluorinated random copolymers, well‐defined block‐, graft, and alternating copolymers based on PVDF received more attention in recent years. PVDF‐containing block copolymers that may self‐assemble into well‐ordered morphologies are of particular interest, being potential precursors for functional nanostructured materials applicable in membranes and electronics. This Highlight provides an overview of the routes developed towards these materials via conventional and controlled polymerization techniques. In addition, it discusses their nanoscopic phase behavior and current and potential applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2861–2877     

Assembly of Cerium(III)‐Stabilized Polyoxotungstate Nanoclusters with SeO32−/TeO32− Templates: From Single Polyoxoanions to Inorganic Hollow Spheres in Dilute Solution

A versatile one‐pot strategy was employed to synthesize three cerium(III)‐stabilized polyoxotungstates nanoclusters by combining cerium linkers and SeO₃^2?/TeO₃^2? heteroanion templates: K₃₂Na₁₆[{(XO₃)W₁₀O₃₄}₈{Ce₈(H₂O)₂₀}(WO₂)₄‐ (W₄O₁₂)] ? n H₂O [X=Se, n=81 ( 1 ); X=Te, n=114 ( 2 )] and K₁₂Na₂₂[{(SeO₃)W₁₀O₃₄}₈{Ce₈(H₂O)₂₀}(WO₂)₄‐ {(W₄O₆)Ce₄(H₂O)₁₄(SeO₃)₄(NO₃)₂}] ? 79 H₂O ( 3 ), which are the first lanthanide‐containing polyoxotungstates with selenium or tellurium heteroatoms. The three clusters were characterized by single‐crystal X‐ray structure analysis, IR spectroscopy, thermogravimetric/differential thermal analysis, UV/Vis spectroscopy, ESI‐MS, and X‐ray photoelectron spectroscopy. Their electrochemical, photoluminescence, and magnetic properties were investigated. Their behavior in solution was studied by transmission electron microscopy, which showed that their single polyoxoanions assemble into intact, uniform‐sized, purely inorganic hollow spheres in dilute water/acetone solution.     

Fast Synthesis of PbS Nanocrystals in Aqueous Solution with Shape Evolution from Cubic to Octahedral Structures and Their Assembled Structures

In this study, we have developed for the first time a fast and energy‐efficient method for the synthesis of PbS nanocrystals with systematic shape evolution from cubic to truncated cubic, cuboctahedral, truncated octahedral, and octahedral structures. The method involves the addition of a small volume of preheated lead acetate and thioacetamide (TAA) mixture to an aqueous growth solution of lead acetate, thioacetamide, cetyltrimethylammonium bromide, and nitric acid. By varying the amount of thioacetamide added to the growth solution, PbS nanocrystals with different morphologies were generated in 2 h at 90 °C. Slight experimental modifications were adopted to generate truncated octahedra. The nanocrystals have very uniform dimensions with average sizes of 32–47 nm. Their structures have been extensively examined by electron microscopy. Nanocube sizes can also be tuned within a range. UV/Vis absorption spectra of PbS cubes, cuboctahedra, and octahedra all show decreasing but continuous absorption from 300 nm to beyond 1000 nm. By monitoring the speed of darkening of solution color, particle growth rate was found to be fastest for nanocubes, followed by truncated cubes, cuboctahedra, and octahedra. These monodisperse nanocrystals can readily form self‐assembled structures. Truncated cubes and octahedra that form monolayer and multilayer packing arrangements have also been studied. This green approach to the synthesis of PbS nanocrystals with fine size and shape control should allow for investigations of their facet‐dependent properties and the fabrication of novel heterostructures.     

Imidazole‐coordinated monodentate NHC–Pd(II) complex derived from proline and its application to the coupling reaction of arylboronic acids with carboxylic acid anhydrides in water at room temperature

Cleavage of a C N bond of imidazolium salt derived from N‐phenyl‐substituted proline was observed in this laboratory. A novel imidazole‐coordinated monodentate NHC–Pd(II) complex 5 was obtained as the sole product in good yield in the reaction of imidazolium salt 4 with Pd(OAc)₂ in refluxing THF. The structure of complex 5 was determined unambiguously by an X‐ray diffraction. The complex was found to be a good catalyst in the cross‐coupling reaction of arylboronic acids with carboxylic acid anhydrides in water at room temperature. Copyright © 2011 John Wiley & Sons, Ltd.