The use of crystallization as a tool to control the self-assembly of polymeric and molecular amphiphiles in solution is attracting growing attention for the creation of non-spherical nanoparticles ...and more complex, hierarchical assemblies. In particular, the seeded growth method termed living crystallization-driven self-assembly (CDSA) has been established as an ambient temperature and potentially scalable platform for the preparation of low dispersity samples of core-shell fiber-like or platelet micellar nanoparticles. Significantly, this method permits predictable control of size, and access to branched and segmented structures where functionality is spatially-defined. Living CDSA operates under kinetic control and shows many analogies with living chain-growth polymerizations of molecular organic monomers that afford well-defined covalent polymers of controlled length except that it covers a much longer length scale (
ca.
20 nm to 10 μm). The method has been applied to a rapidly expanding range of crystallizable polymeric amphiphiles, which includes block copolymers and charge-capped homopolymers, to form assemblies with crystalline cores and solvated coronas. Living CDSA seeded growth methods have also been transposed to a wide variety of π-stacking and hydrogen-bonding molecular species that form supramolecular polymers in processes termed "living supramolecular polymerizations". In this article we outline the main features of the living CDSA method and then survey the promising emerging applications for the resulting nanoparticles in fields such as nanomedicine, colloid stabilization, catalysis, optoelectronics, information storage, and surface functionalization.
The use of crystallization as a tool to control the self-assembly of polymeric and molecular amphiphiles in solution is attracting growing attention for the creation of non-spherical nanoparticles and more complex, hierarchical assemblies.
This Perspective outlines recent advances concerning the formation and potential uses of block copolymer micelles, a class of soft-matter-based nanoparticles of growing importance. As a result of ...rapidly expanding interest since the mid-1990s, substantial advances have been reported in terms of the development of morphological diversity, structural complexity, control over micelle dimensions, scale-up, and applications in a range of areas from nanocomposites to nanomedicine.
Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but ...on a longer length scale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side by side or end to end in nonsolvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and one-dimensional (1D) or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicrometer-length scale, features that are generally only found in natural materials.
This concluding article assesses the past decade of international scholarship on the European Union (EU) and normative power as represented by the contributions to the special issue. It argues that ...the normative power approach (NPA) makes it possible to explain, understand and judge the EU in global politics by rethinking the nature of power and actorness in a globalizing, multilateralizing and multipolarizing era. To do this, the article assesses the past decade in terms of normative power engagement, internationalization and comparison. The article then argues that rethinking power and actorness involves reassessing global theory and pouvoir normatif in action. The article concludes by setting out three ways of developing the NPA in its second decade: macro-approach, meso-characterization and micro-analysis. Following the suggestion of Emanuel Adler, Barry Buzan and Tim Dunne, the article sets out how studying the normative foundations of power through the NPA combines the normative rethinking of power and actorness with the structural changes of a globalizing, multilateralizing and multipolarizing era.
Synthetic Covalent and Non-Covalent 2D Materials Boott, Charlotte E.; Nazemi, Ali; Manners, Ian
Angewandte Chemie (International ed.),
November 16, 2015, Letnik:
54, Številka:
47
Journal Article
Recenzirano
The creation of synthetic 2D materials represents an attractive challenge that is ultimately driven by their prospective uses in, for example, electronics, biomedicine, catalysis, sensing, and as ...membranes for separation and filtration. This Review illustrates some recent advances in this diverse field with a focus on covalent and non‐covalent 2D polymers and frameworks, and self‐assembled 2D materials derived from nanoparticles, homopolymers, and block copolymers.
No plane, no gain: 2D structures have emerged as attractive functional materials over the past few decades. The development of new synthetic methods that allows their creation from a variety of building blocks, including small molecules, nanoparticles, and block copolymers, is expected to pave the way to a range of applications.
Catalytic reactions that enable the formation of new bonds to carbon centres play a pervasive role in the state-of-the-art synthesis of organic molecules and macromolecules. In contrast, the ...development of analogous processes as routes to main group compounds and materials has been much slower. Nevertheless, recent advances have led to a broad expansion of this field and now allow access to a wide range of catenated structures based on elements across the p block. These breakthroughs have already impacted areas such as hydrogen storage and transfer, functional inorganic polymers and ceramic thin films. Dehydrogenation and dehydrocoupling processes are particularly well developed and may be mediated by either transition metal or main group catalysts. Such pathways represent an increasingly attractive and convenient alternative to traditional routes, such as salt metathesis and reductive coupling reactions. An overview of this emerging area is presented in this Review with a focus on recent developments and future challenges.
Chemical compounds that may be used as sources for dihydrogen are discussed. In particular, the use of ammonia-borane and related compounds as hydrogen donors are examined.
Although solution self-assembly of block copolymers (BCPs) represents one of the most promising approaches to the creation of nanoparticles from soft matter, the formation of non-centrosymmetric ...nanostructures with shape anisotropy remains a major challenge. Through a combination of crystallization-driven self-assembly of crystalline-coil BCPs in solution and selective micelle corona cross-linking, we have created short (about 130 nanometers), monodisperse cylindrical seed micelles that grow unidirectionally. These nanostructures grow to form long, non-centrosymmetric cylindrical A-B and A-B-C block co-micelles upon the addition of further BCPs. We also illustrate the formation of amphiphilic cylindrical A-B-C block co-micelles, which spontaneously self-assemble into hierarchical star-shaped supermicelle architectures with a diameter of about 3 micrometers. The method described enables the rational creation of non-centrosymmetric, high aspect ratio, colloidally stable core-shell nanoparticles in a manner that until now has been restricted to the biological domain.
The preparation of well-defined nanoparticles based on soft matter, using solution-processing techniques on a commercially viable scale, is a major challenge of widespread importance. Self-assembly ...of block copolymers in solvents that selectively solvate one of the segments provides a promising route to core-corona nanoparticles (micelles) with a wide range of potential uses. Nevertheless, significant limitations to this approach also exist. For example, the solution processing of block copolymers generally follows a separate synthesis step and is normally performed at high dilution. Moreover, non-spherical micelles-which are promising for many applications-are generally difficult to access, samples are polydisperse and precise dimensional control is not possible. Here we demonstrate the formation of platelet and cylindrical micelles at concentrations up to 25% solids via a one-pot approach-starting from monomers-that combines polymerization-induced and crystallization-driven self-assembly. We also show that performing the procedure in the presence of small seed micelles allows the scalable formation of low dispersity samples of cylindrical micelles of controlled length up to three micrometres.
The article focuses on the entanglement between the EU's attempts to construct its external actions in global politics and research on the EU as a global actor. The article argues that both the ...development of EU external actions and the sociology of knowledge production surrounding the analysis of these actions suffer from unnecessary dichotomisation. Advocates and analysts of the EU's normative power have argued that the separation of norms and interests, both in terms of policy-making and policy analysis, is impossible. In contrast, advocates and analysts of the EU as a 'normal power', a great power pole in the coming multipolar world, have dichotomised the advocacy of policy-making and the analysis of knowledge production of EU external actions. The article sets out, through an examination of the interlinking of policy-making and policy analysis, how such false dichotomies weaken the sociology of knowledge about the EU and the production of the EU's external actions. The article uses an analytical means of illustrating the deep interdependencies between the sociology of knowledge and production of the EU's external actions. This application illustrates how ideas about external actions are spread from the study of normative power to other normative frameworks, and from analysts to policy-makers in the field of EU external actions. The article concludes that strategic dichotomisation and social diffusion are integral to the social sciences and the production of European integration in making Europe 'normal'.
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