Synthesis of disk-shaped nanoparticle aggregates organized in hierarchical structures in block copolymer matrixes (original) (raw)
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Interfacial Assembly of Nanoparticles in Discrete Block-Copolymer Aggregates
Angewandte Chemie International Edition, 2007
The ability to control the assembly structure of nanoscale materials is critical to understand their collective properties and to develop new materials and devices from nanoscale building blocks. In nature, lipid membranes function as structural scaffolds to organize nanoscale intercellular components. This role of lipids originates from their tendency to self-organize into diverse supramolecular aggregates including micelles, bilayers, vesicles, and liquid-crystalline phases. Amphiphilic block copolymers, man-made analogues of lipids, are becoming increasingly important for the synthesis, manipulation, and assembly of nanoparticles. They have been demonstrated to be effective solubilizing agents to transfer organic-phase nanoparticles into water. Preorganized spherical or cylindrical block-copolymer micelles have been actively explored as a type of confined reactor for the controlled synthesis of nanoparticles. However, in most of the solution-phase studies, the nanoparticles were considered as simple solutes, and the efforts in directing the arrangement of nanoparticles using block copolymers have been largely limited to two-dimensional systems. Herein, we describe a novel solution-phase assembly of CdSe quantum dots (QDs) and a prototypical amphiphilic block copolymer, poly(acrylic acid)-block-polystyrene (PAAb-PS). Importantly, this study demonstrates that the interactions between nanoparticles and block copolymers can drastically alter the morphology of block-copolymer aggregates and can lead to a unique three-dimensional assembly structure of nanoparticles (a nanocavity in the present study) with controllable assembly parameters. Coassemblies of PAA-b-PS and organic-phase nanoparticles, including QDs and magnetic particles, have been prepared previously. However, in those studies, the nanoparticles were passively incorporated into the coassemblies by acting as simple solutes, and they were evenly distributed in block-copolymer micelles. Herein, we show a unique example in which nanoparticles act as active components for the assembly formation. Moreover, we demonstrate that one can control the three-dimensional assembly structure of nanoparticles inside discrete blockcopolymer aggregates by manipulating the interfacial energy of the composite system.
Nanoparticle arrangements in block copolymer particles with microphase-separated structures
Journal of Polymer Science Part B: Polymer Physics, 2011
In this study, metal-polymer particles with microphase-separated structures were prepared by self-organized precipitation, where a good solvent is evaporated from a solution that also contains block copolymer, Au NPs, and a poor solvent. Control of the microphase-separated structure in composite particles consisting of Au NPs and block copolymer was accomplished by changing the Au NP size, the mix ratio, and the copolymerization ratio of the block copolymer. The mor-phology of the inner structures was changed from a lamellar phase to a spherical phase by increasing the Au NP concentration.
Tuning Ordered Pattern of Pd Species through Controlled Block Copolymer Self-Assembly
The journal of physical chemistry. B, 2016
We report a method for the preparation of ordered patterns of Pd species on a substrate based on the use of polystyrene-block-poly(ethylene oxide) copolymer (PS-b-PEO) templates and selective inclusion of palladium (Pd) species in the PEO domains. PS-b-PEO samples of different total molecular masses self-assemble in a cylindrical microphase-separated morphology, in which vertically aligned PEO cylinders, with different diameters depending on the molecular mass, are organized in a hexagonal array of different lateral spacings. The cylindrical nanostructure is maintained after the selective inclusion of Pd species (Pd acetate and Pd nanoparticles (NPs) after reduction of Pd ions of the salt) in the PEO cylinders so that the characteristic sizes (diameters and lateral spacings) of the included Pd species are tuned by the characteristic sizes of the block copolymer (BCP) template, which are regulated by molecular mass. Treatment of nanocomposites at elevated temperatures in air removes ...
Polymers, 2021
Nanocomposites containing palladium nanoparticles were synthesized by in situ generation route from palladium acetate and a polyether block amide matrix with the aim to obtain materials with specific nanoparticle location and function properties. The chosen Pebax matrix was composed of a continuous soft phase containing dispersed semi-crystalline rigid domains. Nanocomposite films with Pd amount up to 30 wt% (corresponding to 3.5 vol%) were directly prepared from the palladium precursor and the copolymer matrix through a solvent cast process. The microstructure of the films was investigated by microcalorimetry, X-ray diffraction analyses and transmission electron microscopy. The nanocomposites’ function properties in terms of electrical conductivity and interaction towards hydrogen were studied as a function of the palladium content. It was shown that the spherical crystalline Pd nanoparticles that were in situ formed were located in the continuous soft phase of the copolymer matrix...
Thin-film morphologies of block copolymers with nanoparticles
Powder Diffraction, 2015
Diblock copolymers (BCPs) show phase separation on mesoscopic length scales and form ordered morphologies in both bulk and thin films, the latter resulting in nanostructured surfaces. Morphologies in thin films are strongly influenced by film parameters, the ratio of film thickness and bulk domain spacing. Laterally structured polymer surfaces may serve as templates for controlled assembly of nanoparticles (NPs). We investigated the BCP of poly(n-pentyl methacrylate) and poly (methyl methacrylate) which show bulk morphologies of stacked lamellae or hexagonally packed cylinders. Thin films were investigated by atomic force microscopy and grazing-incidence small-angle X-ray scattering. For film thicknesses f well below d bulk , standing cylinder morphologies were observed in appropriate molar ratios, while film thicknesses around and larger than d bulk resulted in cylinders arranged parallel to surface. To alter and/or improve the morphology also in presence of different NPs (e.g., silica, gold), solvent vapour annealing (SVA) was applied. The BCP morphology usually remains unchanged but periodicities change depending on type and amount of incorporated NPs. It was found that silica clusters enlarge lateral distances of cylinders, whereas Au NPs reduce it. The effect of SVA is weak. The quality of morphology is slightly improved by SVA and lateral distances remain constant or are slightly reduced.
Nanoscale Block Copolymer Templates Decorated by Nanoparticle Arrays
Macromolecules, 2007
We present a novel one-step assembly process that encompasses in-situ formation of silver nanoparticles (NP), directed assembly of block copolymers into a perpendicular lamellar morphology, and NP organization into patterned arrays. This process utilizes organometallic precursors that thermally decompose and form spatially organized NP arrays on the free surface of the block copolymer. As NP concentration increases, the conversion of perpendicular to parallel lamellar morphology at the free surface slows down. A cell dynamical system (CDS) simulation captures the dynamics of this reorganization. The final structure is attractive for producing nanodevices because the surface is decorated by NP that are arranged in parallel arrays with tunable NP separation.
Chemical engineering transactions, 2021
As the advantageous properties of nanoparticles (NPs) often emerge only when appropriate coupling and exchange phenomena between the NPs can take place, the control of the inter-particle distance, regular ordering, and location of the nanoparticles onto solid supports is a critical issue. A robust method to control the spatial organization of NPs onto solid supports, based on the use of self-assembling di-block copolymers (BCPs) as structure-guiding material, is reported. Two different polystyrene-b-poly(methyl methacrylate) (PSb-PMMA) BCPs, characterized by a different PS volume fraction, were used as matrices for the fabrication of nanocomposite thin films with cylindrical and lamellar morphologies controlled at the nanoscale. Selective inclusion of surface functionalized gold (Au) and zinc oxide (ZnO) NPs of appropriate size in the PS nanodomains was achieved from dispersions of the BCPs and NPs in a common solvent. The orientation of the BCPs cylinder and lamellar nanodomains in spin-coated thin films was controlled by solvent and thermal annealing protocols, coupled with techniques of surface neutralization.
Block copolymer nanostructures
Nano Today, 2008
Block copolymers occupy a huge area of research because they offer a vast range of possibilities for architecture, size, and chemical composition. Advances in polymer chemistry 1 , such as anionic polymerisation 2 and most recently living radical polymerization 3 , have enabled a vast array of block copolymers to be synthesized with great control over their architecture, molecular weight, chemical composition, and functionality. Their intrinsic multi-properties allow the combination of different polymers and therefore the design of novel materials potentially comprising several different properties (e.g. thermoplastic, rubber, ductile, electrical conductivity, etc.). In bulk, when the different blocks are chemically immiscible, the balance between the entropically and enthalpically driven phase separation and the chemical bond constraints between the blocks drives the formation of ordered domains 4-10 . In solution, the interactions between the solvent and the different blocks dictate the ability to form well-defined structures. The architecture, molecular weight, volume fractions of blocks, and chemical functionality can all be set in the synthesis, making designer block copolymers a reality. The ability to effectively design nanoparticles and nanostructures to your preference, coupled with the wide range of applications associated with them, have made them an incredibly popular topic of research. Herein,
Self-assembled Block Copolymers for Preparation of Advanced Materials
Block copolymers are attractive candidates for use as templates in the preparation of novel multiphase nanostructured materials due to their ability to control both the length scale and the spatial organization. In this chapter, advanced multifunctional nanocomposites were developed by selective confinement of different nano-objects in one of the domains of the self-assembled block copolymer. To achieve this goal, intermolecular interactions between the block copolymer matrices and the nano-objects were considered in order to design nanostructured materials with enhanced properties. With the aim to fabricate multifunctional materials with potential applications in several fields of Nanotechnology, on the one hand, conductive-thermoreversible nanostructured materials were developed by modification of block copolymers with low molecular weight liquid crystals and inorganic nanoparticles (TiO2 or Au). On the other hand, nanostructured materials with reversible birefringence were achiev...
Controlled Arrangement of Nanoparticle Arrays in Block-Copolymer Domains
Small, 2006
This Review describes recent results on the precise spatial distribution control of metal and semiconductor nanoparticles into domains of microphase-separated block copolymers. Specific focus is directed towards selective incorporation into a specific microphase of a block copolymer. Details on theoretical aspects concerning nanoparticle incorporation as well as practical examples are given. Furthermore, examples on applications and technological aspects of the resulting nanoparticle/polymer nanocomposites are provided.