Self-assembly of anisotropic particles (original) (raw)

Theory and Simulation Studies of Self-Assembly of Helical Particles

Self-Assembling Systems, 2016

Self-assembly-a governing principle by which materials form-is the autonomous organization of matter into ordered arrangements [1, 2]. It is typically associated with thermodynamic equilibrium, the organized structures being characterized by a minimum in the system's free energy, although this definition is too broad. Self-assembling processes are ubiquitous in nature, ranging, for example, from the opalescent inner surface of the abalone shell to the internal compartments of a living cell [3]. By these processes, nanoparticles or other discrete components spontaneously organize due to direct specific interactions and/or indirectly, through their environment. Self-assembly is one of the few practical strategies for making ensembles of nanostructures. It will therefore be an essential part of nanotechnology. Self-assembly is also common to many dynamic, multicomponent systems, from smart materials and self-healing structures to netted sensors and computer networks. In the world of biology, living cells self-assemble, and understanding life will therefore require understanding self-assembly. The cell also offers countless examples of functional self-assembly that stimulate the design of non-living systems [4, 5]. Self-assembly reflects information coded (as shape, surface properties, charge, polarizability, magnetic dipole, mass, etc.) in individual components; these characters determine the interaction among them. The design of building blocks that organize themselves into desired structure and functions is the key to applications of self-assembly [2]. Much of materials science and soft condensed-matter physics in the past century involved the study of self-assembly of fundamental building blocks (typically atoms, molecules, macromolecules, and colloidal particles) into bulk thermodynamic phases [6]. Today, the extent to which these building blocks can be engineered has undergone a quantum leap. Tailor-made, submicrometer particles will be the building blocks of a new generation of nanostructured materials with unique physical properties [7-11]. These new building blocks will be the "atoms" and "molecules" of tomorrow's materials, self-assembling into novel structures made possible solely by their unique design [2]. For example, patchy particles consisting of various Self-Assembling Systems: Theory and Simulation, First Edition. Edited by Li-Tang Yan.

Self-assembly of anisotropic soft particles in two dimensions

The European Physical Journal E, 2013

The self assembly of core-corona discs interacting via anisotropic potentials is investigated using Monte Carlo computer simulations. A minimal interaction potential that incorporates anisotropy in a simple way is introduced. It consists in a core-corona architecture in which the center of the core is shifted with respect to the center of the corona. Anisotropy can thus be tuned by progressively shifting the position of the core. Despite its simplicity, the system self organize in a rich variety of structures including stripes, triangular and rectangular lattices, and unusual plastic crystals. Our results indicate that the amount of anisotropy does not alter the lattice spacing and only influences the type of clustering (stripes, micells, etc.) of the individual particles. *

Fast Generation of Potentials for Self-Assembly of Particles

2009

We address the inverse problem of designing isotropic pairwise particle interaction potentials that lead to the formation of a desired lattice when a system of particles is cooled. The design problem is motivated by the desire to produce materials with pre-specified structure and properties. We present a heuristic computation-free geometric method, as well as a fast and robust trend optimization method that lead to the formation of high quality honeycomb lattices. The trend optimization method is particularly successful since it is well-suited to efficient optimization of the noisy and expensive objective functions encountered in the self-assembly design problem. We also present anisotropic potentials that robustly lead to the formation of the kagome lattice, a lattice that has not previously been obtained with isotropic potentials.

Active structuring of colloids through field-driven self-assembly

Current Opinion in Colloid & Interface Science, 2019

In recent years self-assembly has become progressively more "active", i.e. the focus of research gradually has shifted towards field-manipulation of matter in order to form temporary states rather than creating static architectures. The desire for timeprogrammed control of materials certainly originates from the unmatched complexity of natural systems that orchestrate multiple components across length scales. Although artificial selfassembly still lacks control comparable to natural systems, there has been impressive progress in a concerted approach from physicists, chemists, biologists, and engineers. This review summarizes the current trend in colloidal assembly advancing from static assembly of isotropic particles towards active structuring of anisotropic particles with heterogeneous (patchy) surfaces, and ultimately, to complex behavior in dissipative dynamic systems. We focus both on the formation of static structures and on temporary states due to response to magnetic, electric, or optic stimulation. We give examples of nano-and microparticle assembly where the temporary state may adopt equilibrium order or a continuously changing dynamic pattern.

Helix Self-Assembly from Anisotropic Molecules

Physical Review Letters, 2007

We explore the potential energy landscape for clusters composed of disklike ellipsoidal particles interacting via an anisotropic potential based on the elliptic contact function. Over a wide range of parameter space we find global potential energy minima consisting of helices composed of one or more strands. Characterizing the potential energy surface in the region of helical global minima reveals a topology associated with ''structure-seeking'' systems. This result indicates that the helices will selfassemble over a wide range of temperature.

Self-assembly scenarios of patchy colloidal particles in two dimensions

Journal of Physics: Condensed Matter, 2010

The rapid progress in precisely designing the surface decoration of patchy colloidal particles offers a new, yet unexperienced freedom to create building entities for larger, more complex structures in soft matter systems. However, it is extremely difficult to predict the large variety of ordered equilibrium structures that these particles are able to undergo under the variation of external parameters, such as temperature or pressure. Here we show that, by a novel combination of two theoretical tools, it is indeed possible to predict the self-assembly scenario of patchy colloidal particles: on one hand, a reliable and efficient optimization tool based on ideas of evolutionary algorithms helps to identify the ordered equilibrium structures to be expected at T = 0; on the other hand, suitable simulation techniques allow to estimate via free energy calculations the phase diagram at finite temperature. With these powerful approaches we are able to identify the broad variety of emerging self-assembly scenarios for spherical colloids decorated by four patches and we investigate the stability of the crystal structures on modifying in a controlled way the regular tetrahedral arrangement of the patches.

Shaping colloids for self-assembly

Nature Communications, 2013

The creation of a new material often starts from the design of its constituent building blocks at a smaller scale. From macromolecules to colloidal architectures, to granular systems, the interactions between basic units of matter can dictate the macroscopic behaviour of the resulting engineered material and even regulate its genesis. Information can be imparted to the building units by altering their physical and chemical properties. In particular, the shape of building blocks has a fundamental role at the colloidal scale, as it can govern the self-organization of particles into hierarchical structures and ultimately into the desired material. Herein we report a simple and general approach to generate an entire zoo of new anisotropic colloids. Our method is based on a controlled deformation of multiphase colloidal particles that can be selectively liquified, polymerized, dissolved and functionalized in bulk. We further demonstrate control over the particle functionalization and coating by realizing patchy and Janus colloids.