Precise Synthesis and Thin Film Self-Assembly of PLLA-b-PS Bottlebrush Block Copolymers

The ability of bottlebrush block copolymers (BBCPs) to self-assemble into ordered large periodic structures could greatly expand the scope of photonic and membrane technologies. In this paper, we describe a two-step synthesis of poly(l-lactide)-b-polystyrene (PLLA-b-PS) BBCPs and their rapid thin-film self-assembly. PLLA chains were grown from exo-5-norbornene-2-methanol via ring-opening polymerization (ROP) of l-lactide to produce norbornene-terminated PLLA. Norbonene-terminated PS was prepared using anionic polymerization followed by a termination reaction with exo-5-norbornene-2-carbonyl chloride. PLLA-b-PS BBCPs were prepared from these two norbornenyl macromonomers by a one-pot sequential ring opening metathesis polymerization (ROMP). PLLA-b-PS BBCPs thin-films exhibited cylindrical and lamellar morphologies depending on the relative block volume fractions, with domain sizes of 46–58 nm and periodicities of 70–102 nm. Additionally, nanoporous templates were produced by the selective etching of PLLA blocks from ordered structures. The findings described in this work provide further insight into the controlled synthesis of BBCPs leading to various possible morphologies for applications requiring large periodicities. Moreover, the rapid thin film patterning strategy demonstrated (>5 min) highlights the advantages of using PLLA-b-PS BBCP materials beyond their linear BCP analogues in terms of both dimensions achievable and reduced processing time.     

Transition-metal-templated synthesis of rotaxanes and catenanes: From small molecules to polymers

This article provides an overview of the fundamental principles of the synthesis of metallocatenanes and metallorotaxanes. It also describes the synthesis and properties of electronic conducting polymers—polypyrrole and polythiophene—built around metallocatenanes and metallorotaxanes. The particular properties of this new class of polymers, including the possibility of transmetallation reactions being performed with them and the observation of electronic coupling between the metal centers and the conducting matrix, are discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3470–3477, 2003     

Template atom transfer radical polymerization of a diaminopyrimidine‐derivatized monomer in the presence of a uracil‐containing polymer

Uracil‐derivatized monomer 6‐undecyl‐1‐(4‐vinylbenzyl)uracil and diaminopyrimidine‐derivatized monomer 2,6‐dioctanoylamido‐4‐methacryloyloxypyrimidine (DMP) were synthesized and polymerized by atom transfer radical polymerization (ATRP). A well‐defined, highly soluble, uracil‐containing polymer, poly[6‐undecyl‐1‐(4‐vinylbenzyl)uracil] (PUVU), was prepared in dioxane at 90 °C with CuBr/1,1,4,7,10,10‐hexamethyltriethylenetetramine as the catalyst and methyl α‐bromophenylacetate as the initiator. PUVU was further used as a template for the ATRP of DMP. The enhanced apparent rate constant of the DMP polymerization in the presence of PUVU indicated that the ATRP of DMP occurred along the PUVU template. The template polymerization produced a stable and insoluble macromolecular complex, PUVU/poly(2,6‐dioctanoylamido‐4‐methacryloyloxypyrimidine). An X‐ray diffraction study confirmed that the complex had strandlike domains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6607–6615, 2006     

TiO2一维纳米材料及其纳米结构的合成

本文对合成TiO₂一维纳米材料及其有序纳米阵列的阳极氧化法、模板法以及水热法进行了全面而系统的评述，着重介绍了它们的最新研究进展。阳极氧化法能制备牢固负载于基体上的TiO₂纳米管阵列，这有助于构筑TiO₂纳米结构及其在纳米器件上的应用；与多种制备技术如溶胶－凝胶工艺、电化学沉积以及原子层沉积等相结合，模板法可以合成出多种形貌的TiO₂纳米材料如纳米管、纳米线和纳米棒，并可以通过改变所用模板的微观尺寸来调控TiO₂一维纳米材料及其有序阵列的微结构参数；水热合成法可以制备出直径小且比表面积大的TiO2纳米管粉末。但从目前看来，该法还不能制备出牢固负载于基体上的有序纳米阵列。文章最后指出了TiO₂一维纳米材料及其有序纳米阵列合成中存在的问题及今后发展方向。     

Organic templates for the generation of inorganic materials

Mankind's fascination with shapes and patterns, many examples of which come from nature, has greatly influenced areas such as art and architecture. Science too has long since been interested in the origin of shapes and structures found in nature. Whereas organic chemistry in general, and supramolecular chemistry especially, has been very successful in creating large superstructures of often stunning morphology, inorganic chemistry has lagged behind. Over the last decade, however, researchers in various fields of chemistry have been studying novel methods through which the shape of inorganic materials can be controlled at the micro- or even nanoscopic level. A method that has proven very successful is the formation of inorganic structures under the influence of (bio)organic templates, which has resulted in the generation of a large variety of structured inorganic structures that are currently unattainable through any other method.     

Needle-like calcium carbonate assisted self-assembly of mesostructured hollow silica nanotubes

Mesostructured hollow silica nanotubes (MHSNTs) were successfully produced via the self-assembly of C₁₆TMABr and silica species on the surface of needle-like calcium carbonate nanoparticles in an alkaline medium at room temperature. The characterization of MHSNTs by transmission electron microscopy (TEM), scanning electron microscopy (SEM), pore size distribution (PSD) and Brunauer-Emmett-Teller (BET) indicated that MHSNTs had uniform tubular hollow structures with big openings, a length of 1.5-2.0 μm, an inner diameter of 150-200 nm at the open end and 50-60 nm at the closed end, and a wall thickness of 20-30 nm, as well as a narrow PSD around 2.3 nm in the shells and a BET surface area as high as ∼975.3 m²/g. By small-angle X-ray diffraction (XRD), BET and pore structure analysis, it was found that more uniformly structured mesopores could be formed by the method of removing the double templates simultaneously through a solvent extraction process, as compared to the separate removal of the double templates by calcinating and then etching in an acidic solution, and the amount of C₁₆TMABr affected the mesoporous structures of MHSNTs greatly. The formation processes of MHSNTs were also studied with XRD and FTIR.     

Functional Fe–Pd nanomaterials synthesized by template-assisted methods

In this work, we highlight our recent progress in the synthesis and characterization of functional nanomaterials based on Fe–Pd ferromagnetic alloys by means of template-assisted deposition techniques employing highly ordered nanoporous alumina membranes, such as ordered arrays of nanowires and antidots thin films. Special attention is paid on their basic magnetic properties, such as coercivity, remanence and magnetic anisotropy, and their dependence on the microstructure and morphological parameters of the ordered arrays.     

Multi‐walled carbon nanotube modified dummy‐template magnetic molecularly imprinted microspheres as solid‐phase extraction material for the determination of polychlorinated biphenyls in fish

Novel multi‐walled carbon nanotube modified dummy‐template molecularly imprinted microspheres (MWCNTs@DMMIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs). MWCNTs@DMMIPs were prepared by a surface molecular imprinting technique. Core–shell Fe₃O₄@SiO₂ nanoparticles were employed as magnetic support. 3,4‐Dichlorobenzene acetic acid was used as a dummy template instead of PCBs, methacrylic acid was used as functional monomer and ethylene glycol dimethacrylate was used as the cross‐linker. The resulting absorbent was characterized by various methods. The adsorbent was employed for extracting PCBs and exhibited good selectivity and high adsorption efficiency. Furthermore, it was reusable and capable of magnetic separation. Adsorption kinetics fit well with a pseudo‐second‐order kinetic equation and also exhibited a three‐stage intra‐particle diffusion model. The Freundlich model was used to describe the adsorption isotherms. The materials were successfully applied to the magnetic dispersive solid‐phase extraction of six kinds of PCBs followed by gas chromatography with mass spectrometry determination in fish samples, the limit of detection of six kinds of PCBs were 0.0028–0.0068 μg/L and spiked recoveries ranged between 73.41 and 114.21%. The prepared adsorbent was expected to be a new material for the removal and recovery of PCBs from contaminated foods.     

Formation of a Single-Crystal Aluminum-Based MOF Nanowire with Graphene Oxide Nanoscrolls as Structure-Directing Agents

An innovative strategy is proposed to synthesize single-crystal nanowires (NWs) of the Al³⁺ dicarboxylate MIL-69(Al) MOF by using graphene oxide nanoscrolls as structure-directing agents. MIL-69(Al) NWs with an average diameter of 70±20 nm and lengths up to 2 μm were found to preferentially grow along the [001] crystallographic direction. Advanced characterization methods (electron diffraction, TEM, STEM-HAADF, SEM, XPS) and molecular modeling revealed the mechanism of formation of MIL-69(Al) NWs involving size-confinement and templating effects. The formation of MIL-69(Al) seeds and the self-scroll of GO sheets followed by the anisotropic growth of MIL-69(Al) crystals are mediated by specific GO sheets/MOF interactions. This study delivers an unprecedented approach to control the design of 1D MOF nanostructures and superstructures.     

Non‐Lithography Hydrodynamic Printing of Micro/Nanostructures on Curved Surfaces

A key issue of micro/nano devices is how to integrate micro/nanostructures with specified chemical components onto various curved surfaces. Hydrodynamic printing of micro/nanostructures on three‐dimensional curved surfaces is achieved with a strategy that combines template‐induced hydrodynamic printing and self‐assembly of nanoparticles (NPs). Non‐lithography flexible wall‐shaped templates are replicated with microscale features by dicing a trench‐shaped silicon wafer. Arising from the capillary pumped function between the template and curved substrates, NPs in the colloidal suspension self‐assemble into close‐packed micro/nanostructures without a gravity effect. Theoretical analysis with the lattice Boltzmann model reveals the fundamental principles of the hydrodynamic assembly process. Spiral linear structures achieved by two kinds of fluorescent NPs show non‐interfering photoluminescence properties, while the waveguide and photoluminescence are confirmed in 3D curved space. The printed multiconstituent micro/nanostructures with single‐NP resolution may serve as a general platform for optoelectronics beyond flat surfaces.