Synthesis and assembly of structured colloidal particles

Abstract

Synthesis and self-assembly of structured colloids is a nascent field. Recent advances in this area include the development of a variety of practical routes to produce robust photonic band-gap materials, colloidal lithography for nanopatterns, and hierarchically structured porous materials with high surface-to-volume ratios for catalyst supports. To improve their properties, non-conventional suprastructures have been proposed, which could be built up using binary or bimodal mixtures of spherical particles and particles with internal or surface nanostructures. This Feature Article will describe the state-of-the-art in colloidal particles and their assemblies. The paper consists of three main sections categorized by the type of colloid, namely shape-anisotropic particles, chemically patterned particles and internally structured particles. In each section, we will discuss not only synthetic routes to uniform colloids with a range of structures, features and shapes, but also self-organization of these colloids into macrocrystalline structures with varying nanoscopic features and functionalities. Finally, we will outline future perspectives for these colloidal suprastructures. Seung-Man Yang Seung-ManYang received a Ph.D. degree in Chemical Engineering from Caltech in 1985. Following this, he joined the KAIST as a Professor in Chemical and Biomolecular Engineering. He has served the KAIST as a director of the Computing Center, and a Department Chair. Currently, Professor Yang leads the Creative Research Initiative Center for Integrated Optofluidic Systems. His principal contributions have been in theories and experimental methods for fabricating ordered macrocrystalline structures, which can be applied as innovative functional nanoscopic materials such as optoelectronic devices and biosensors. He has authored over 160 peer-reviewed papers, and a number of books and patents in related areas. Gi-Ra Yi Gi-Ra Yi is a senior researcher of Korea Basic Science Institute (KBSI) in Seoul. He received his B.S. (1997) degree in chemical engineering from Yonsei University, and M.S. (1999) and Ph.D. (2003) degrees in chemical and biomolecular engineering from KAIST.

Fabrication, Assembly, and Application of Patchy Particles

“…Selective modification of a segment of a particle surface is directly feasible in the case of the PVD technique because of the inherent shadow effect. In addition to the conventional surface modification techniques, [62,63] more recently capillary flow techniques [13,15,[64][65][66][67] and colloidal assembly [68,69] methods have been explored for the fabrication of patchy particles and therefore will be included here.…”

Binary colloidal structures assembled through Ising interactions

“…Multi-component colloidal systems [26][27][28][29][30][31][32][33][34][35] (that is, 'colloidal alloys') as well as systems of particles with non-trivial internal structure, such as Janus particles [36][37][38][39] and particles with shape anisotropy [40][41][42] , are currently being explored due to their ability to tailor the particle interactions and enable the assembly of diverse crystalline structures. Current methods for assembling ordered structures with two or three particle types include kinetic techniques based on controlled drying [26][27][28][29][30][31] and thermodynamic techniques [32][33][34][35]43,44 that rely on spontaneous assembly into minimum free-energy configurations.…”

Exploring energy landscapes: from molecular to mesoscopic systems

“…There has been an unprecedented growth over the last decade in the synthesis of colloidal building blocks with anisotropy in shape and/or surface chemistry. 32,[109][110][111][112] Unlike isotropic spherical colloids, which have served extensively as model systems for studying phase transitions in atomic systems, 113 these novel building blocks possess directional interactions, commonly associated with molecular building blocks at a smaller length scale, raising the possibility of 'colloidal molecules'. 32,112 Anisotropic colloidal particles, providing scope for tuning the interparticle interactions under laboratory conditions, have proved to be promising building blocks for programmed assembly of functional architectures across length scales.…”