Simulations and experiments of nanorods (NRs) show that co-assembly with block copolymer (BCP) melts leads to the formation of a superstructure of side-to-side NRs perpendicular to the lamellar axis. A mesoscopic model is validated against scanning electron microscopy (SEM) images of CdSe NRs mixed with polystyrene-block-poly(methyl methacrylate). It is then used to study the co-assembly of anisotropic nanoparticles (NPs) with a length in the same order of magnitude as the lamellar spacing. The phase diagram of BCP/NP is explored as well as the time evolution of the NR. NRs that are slightly larger than the lamellar spacing are found to rotate and organize side-to-side with a tilted orientation with respect to the interface. Strongly interacting NPs are found to dominate the co-assembly, while weakly interacting nanoparticles are less prone to form aggregates and tend to form well-ordered configurations.

Various types of devices require hierarchically nano-patterned substrates, where spacing between patterned domains is controlled. Ultra-confined films exhibit extreme morphological sensitivity to slight variations in film thickness when the substrate is highly selective toward one of the blocks. Here, it is shown that using the substrate’s topography as a thickness differentiating tool enables the creation of domains with different surface patterns in a fully controlled fashion from a single, unblended block copolymer. This approach is applicable to block copolymers of different compositions and to different topographical patterns, and thus opens numerous possibilities for hierarchical construction of multifunctional devices.

Polyelectrolyte multilayers (PEMs) assembled layer-by-layer have emerged as functional polymer films that are both stable and capable of containing drug molecules for controlled release applications. Most of these applications concentrate on sustained release, where the concentration of the released molecules remains rather constant with time. However, high-efficiency delivery requires obtaining high local concentrations at the vicinity of the cells, which is achieved by triggered release. Here, we show that a nanopatterned PEM platform demonstrates superior properties with respect to drug retention and triggered delivery. A chemically modified block copolymer film was used as a template for the selective deposition of poly(ethylene imine) and a charged derivative of the electroactive poly(3,4-ethylenedioxythiophene) together with a drug molecule. This nanopatterned PEM shows the following advantages: (1) high drug loading; (2) enhanced retention of the bioactive molecule; (3) release triggered by an electrochemical stimulus; (4) high efficacy of drug delivery to cells adsorbed on the surface compared to the delivery efficacy of a similar concentration of drug to cells suspended in a solution.

Block copolymer guided assembly of nanoparticles leads to the formation of nanocomposites with periodic arrangement of nanoparticles, which are important for applications such as photonic devices and sensors. However, linear block copolymers offer limited control over the internal arrangement of nanoparticles inside their hosting domains. In contrast, bottlebrush block copolymers possess unique architectural attributes that enable additional ways to control the local organization of nanoparticles. In this work, we studied the coassembly of 8 and 13 nm gold nanoparticles with three bottlebrush block copolymers differing in the asymmetry of their graft lengths. Assembly was performed in ultraconfined films, where it occurs quasi-two-dimensionally. Our results indicate that graft asymmetry could be used as an additional tool to enhance nanoparticle ordering by forcing them to localize at the center of the domain regardless of their size. This behavior is analyzed in terms of the influence of the graft asymmetry on the average conformations of the blocks.

Exploiting the full potential of metal and semiconductor nanoparticles for advanced nanotechnological applications requires their organization into predefined structures with high orientational control. Nanofabrication approaches that combine high resolution lithography and self-assembly afford the advantages of accurate placement, compositional diversity, and reduced production costs. This review concentrates on the creation of organized nanoparticle superstructures assisted by recent developments in the directed self-assembly of block copolymers, and delineates possible applications. Copyright (C) 2016 John Wiley & Sons, Ltd.

Polyelectrolyte multilayers gain their importance from their applicability to a wide variety of functional building blocks. The ability to create these multilayers as laterally nano-patterned films, which has only been scarcely investigated so far, augments the functionality of the multilayer and makes it valuable for applications that require nanoscale features or periodic arrangement, such as photonic devices, catalytic surfaces, and biomedical applications. In this study we reveal how the lateral confinement imposed by block copolymer nano-domains in thin film templates affects the assembly of the deposited poly electrolyte layers at different ionic strengths, and how the combined effects of nano-confinement and ionic strength dictate the final structure of the multilayer. These fundamental insights provide the basis for successful construction of nano-patterned, functional coatings. (C) 2017 Elsevier Ltd. All rights reserved.

The construction of nano-sized, two-dimensionally ordered nanoparticle (NP) superstructures is important for various advanced applications such as photonics, sensing, catalysis, or nano-circuitry. Currently, such structures are fabricated using the templated organization approach, in which the templates are mainly created by photo-lithography or laser-lithography and other invasive top-down etching procedures. In this work, we present an alternative bottom-up preparation method for the controlled deposition of NPs into hierarchical structures. Lamellar polystyrene-block-poly(2-vinylpyridinium) thin films featuring alternating stripes of neutral PS and positively charged P2VP domains serve as templates, allowing for the selective adsorption of negatively charged gold NPs. Dense NP assembly is achieved by a simple immersion process, whereas two-dimensionally ordered arrays of NPs are realized by microcontact printing (mu CP), utilizing periodic polydimethylsiloxane wrinkle grooves loaded with gold NPs. This approach enables the facile construction of hierarchical NP arrays with variable geometries. Copyright (C) 2016 John Wiley & Sons, Ltd.

ITO electrodes modified with a nanopatterned film of polystyrene-block-poly(2-vinylpyridine), PS-b-P2VP, where the P2VP domains are quaternized with iodomethane, are used for selective deposition of redox-active materials. Electrochemical studies (cyclic voltammetry, Faradaic impedance measurements) indicate that the PS domains insulate the conductive surface toward redox labels in solution. In turn, the quaternized P2VP domains electrostatically attract negatively charged redox labels solubilized in the electrolyte solution, resulting in an effective electron transfer between the electrode and the redox label. This phenomenon is implemented for the selective deposition of the electroactive Prussian blue on the nanopatterned surface and for the electrochemical deposition of Au nanoparticles, modified with a monolayer of p-aminothiophenol/2-mercaptoethanesulfonic acid, on the quaternized P2VP domains. The patterned Prussian blue-modified surface enables controlling the wettability properties by the content of the electrochemically deposited Prussian blue. Controlled wettability is unattainable with the homopolymer-modified surface, attesting to the role of the nanopattern.

A block copolymer-based assembly approach for the creation of nano-patterned polyelectrolyte multilayers over cm²-scale areas is presented. Up to 5 bi-layers were selectively assembled on top of specific nanodomains featuring different morphologies. The successful isolation of nanoscale objects corresponding in shape to the template features is also demonstrated. This methodology is applicable to different types of polyelectrolytes, and opens up a new dimension for layer-by-layer construction.

A 7-pyrrolidino-7-benzylamino-8,8-dicyanoquinodimethane, PBEDQ, (1), donor-acceptor-modified electrode yields, in the presence of hydroquinone, (2), an anodic photocurrent with quantum efficiency of 1.5%. The PBEDQ-functionalized electrode yields, in the presence of the electron acceptor diquat, (3), a cathodic photocurrent with a quantum efficiency corresponding to 2.1%. The electron transfer cascades leading to the anodic or cathodic photo currents in the different systems are discussed. It is further demonstrated that the integration of 1,4-dihydronicotinamide adenine dinucleotide, NADH, as electron donor, with the PBEDQ-modified electrode leads to an anodic photocurrent. This allowed the assembly of a photobioelectrochemical integrated electrode composed of the photoactive PBEDQ donor-acceptor compound, NAD(+) as cofactor, and the NAD(+)-dependent glucose dehydrogenase, GDH. Irradiation of the integrated electrode in the presence of glucose results in the GDH-biocatalyzed oxidation of glucose to gluconic acid with the concomitant generation of NADH that acts as electron donor for the photo active donor-acceptor PBEDQ units, leading to the generation of steady-state anodic photocurrent. The photocurrent intensities are controlled by the concentrations of glucose. The integrated PBEDQ/NAD(+)/GDH electrodes introduces a functional photobioelectrochemical electrode for the detection of glucose, and demonstrates the assembly of a functional photo-biofuel cell that uses light and a biomass product (glucose) for the generation of electric power.

The combination of block copolymer templating with electrostatic self-assembly provides a simple and robust method for creating nano-patterned polyelectrolyte multilayers over large areas. The deposition of the first polyelectrolyte layer provides important insights on the initial stages of multilayer buildup. Here, we focus on two-dimensionally confined ``dots'' patterns afforded by block copolymer films featuring hexagonally-packed cylinders that are oriented normal to the substrate. Rendering the cylinder caps positively charged enables the selective deposition of negatively charged polyelectrolytes on them under salt-free conditions. The initially formed polyelectrolyte nanostructures adopt a toroidal (''doughnut'') shape, which results from retraction of dangling polyelectrolyte segments into the ``dots'' upon drying. With increasing exposure time to the polyelectrolyte solution, the final shape of the deposited polyelectrolyte transitions from a doughnut to a hemisphere. These insights would enable the creation of patterned polyelectrolyte multilayers with increased control over adsorption selectivity of the additional incoming polyelectrolytes. (C) 2016 Elsevier Ltd. All rights reserved.

Nano-patterned materials are beneficial for applications such as solar cells, opto- electronics, and sensing owing to their periodic structure and high interfacial area. Here, we present a non-lithographic approach for assembling polyelectrolytes into periodic nanoscale patterns over cm(2)-scale areas. Chemically modified block copolymer thin films featuring alternating charged and neutral domains are used as patterned substrates for electrostatic self-assembly. In-depth characterization of the deposition process using spectroscopy and microscopy techniques, including the state-of-the-art scanning transmission X-ray microscopy (STXM), reveals both the selective deposition of the polyelectrolyte on the charged copolymer domains as well as gradual changes in the film topography that arise from further penetration of the solvent molecules and possibly also the polyelectrolyte into these domains. Our results demonstrate the feasibility of creating nano-patterned polyelectrolyte layers, which opens up new opportunities for structured functional coating fabrication.

Quasi-block copolymers (q-BCPs) are block copolymers consisting of conventional and supramolecular blocks, in which the conventional block is end-terminated by a functionality that interacts with the supramolecular monomer (a ``chain stopper'' functionality). A new design of q-BCPs based on a general polymeric chain stopper, which consists of polystyrene end-terminated with a sulfonate group (PS-SO3Li), is described. Through viscosity measurements and a detailed diffusion-ordered NMR spectroscopy study, it is shown that PS-SO3Li can effectively cap two types of model supramolecular monomers to form q-BCPs in solution. Furthermore, differential scanning calorimetry data and structural characterization of thin films by scanning force microscopy suggests the existence of the q-BCP architecture in the melt. The new design considerably simplifies the synthesis of polymeric chain stoppers; thus promoting the utilization of q-BCPs as smart, nanostructured materials.