scholarly journals Controlling Self-Assembled Periodic Structures of Colloidal Particles by Convective Self-Assembly

2017 ◽  
Vol 54 (1) ◽  
pp. 23-26
Author(s):  
Kohei Shimizu ◽  
Satoshi Watanabe ◽  
Minoru T. Miyahara
Soft Matter ◽  
2021 ◽  
Author(s):  
Jiawei Lu ◽  
Xiangyu Bu ◽  
Xinghua Zhang ◽  
Bing Liu

The shapes of colloidal particles are crucial to the self-assembled superstructures. Understanding the relationship between the shapes of building blocks and the resulting crystal structures is an important fundamental question....


Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 877
Author(s):  
Brunno C. Rocha ◽  
Sanjib Paul ◽  
Harish Vashisth

Entropy plays a key role in the self-assembly of colloidal particles. Specifically, in the case of hard particles, which do not interact or overlap with each other during the process of self-assembly, the free energy is minimized due to an increase in the entropy of the system. Understanding the contribution of entropy and engineering it is increasingly becoming central to modern colloidal self-assembly research, because the entropy serves as a guide to design a wide variety of self-assembled structures for many technological and biomedical applications. In this work, we highlight the importance of entropy in different theoretical and experimental self-assembly studies. We discuss the role of shape entropy and depletion interactions in colloidal self-assembly. We also highlight the effect of entropy in the formation of open and closed crystalline structures, as well as describe recent advances in engineering entropy to achieve targeted self-assembled structures.


1999 ◽  
Vol 576 ◽  
Author(s):  
Byron Gates ◽  
Younan Xia

ABSTRACTThis presentation describes a simple and practical method for self-assembling meso- and nanoparticles into three-dimensionally ordered lattices (opals) over large areas, and the use of these lattices as templates in fabricating highly ordered porous structures such as inverse opals. This method has been applied to a variety of colloidal particles, including silica colloids and polymer beads with diameters in the range of˜50 nm to ˜50 μm. Templating against the 3D opaline lattices provides an effective route to inorganic-organic composite materials and inverse opals having 3D periodic structures.


2002 ◽  
Vol 739 ◽  
Author(s):  
V. Bouda

ABSTRACTThe growth of the self-assembled structure of carbon colloidal particles has been studied [1]. The system of carbon particles was processed in electrical field in polymer melt with controlled ionic concentration. The interpretation of the complex evolution of the self-assembled structure of carbon particles was given in terms of phase transitions of colloidal systems of carbon particles.Interactions between doublets of carbon black (CB) particles are interpreted in terms of DLVO approximation of interaction energy as multiples of average thermal fluctuation kT. Plots of the sum of energy of electrostatic repulsion and energy of van der Waals attraction versus separation between the doublets show the energy barriers to coagulation of high B and the energy wells with the secondary minima of depth W. The colloidal phase transitions appear at critical conjuncture of the concentration of ions in the medium and surface potential on the colloids. Six transition lines determine five phases of the assembly of carbon colloids in the proposed colloidal phase diagram: lateral vapor + axial vapor (vapor), lateral liquid + axial vapor (columnar liquid crystal), lateral liquid + axial liquid (smectic LC), lateral liquid + axial solid (nematic LC), and lateral solid + axial solid (solid).The diagram provides a tool to control the evolution of carbon self-assembly. The eventual morphology depends on the route of the steps of the processing. During the time elapsed in the LC state, the structure can reorganize and the eventual coagulation produces various crystals. On the contrary, the route outside the LC state can produce glass.


2012 ◽  
Vol 554-556 ◽  
pp. 263-267
Author(s):  
Hui Chen ◽  
Xiao Hui Wang ◽  
Dong Li ◽  
Yan Zhu Guo ◽  
Run Cang Sun

Biocompatible quaternary chitosan/sodium alginate multilayer microcapsules were prepared by layer-by-layer (LBL) self-assembly on the template of monodispersed melamine formaldehyde resin microspheres (MF). The process of self-assembly was monitored by measuring the surface zeta-potential of colloidal particles. The particle size was determined by digital light scattering (DLS) after each deposition, and the average thickness of monolayer film was revealed to be 3.9 nm. Using rhodamine B-labeled quaternary chitosan as the positive polyelectrolyte and sodium alginate as the negative polyelectrolyte, self-assembled multilayer microcapsules with strong red-light emitting were obtained and observed with fluorescence microscope. The fluorescent microcapsules self-assembled from the biocompatible natural polysaccharides may be potentially applied in drug delivery and fluorescence diagnosis.


2005 ◽  
Vol 901 ◽  
Author(s):  
Ramazan Asmatulu ◽  
Sejong Kim ◽  
Robin Bright ◽  
Phillip Yu ◽  
Fotios Papadimitrakopoulos ◽  
...  

AbstractControlled defects were created on DNA linked 2-D colloidal photonic crystals using a Nd:YAG pulsed laser. The 2-D photonic crystals were self-assembled using 1.8 μm polystyrene (PS) microspheres on functionalized glass substrates. To synthesize the hexagonal close packed crystalline samples, both substrate and particles attached single-strand DNA, sequence A on the substrate and sequence B on the particles. The DNA was hybridized using the DNA linker with complementary single-strand A’B’ that anchored the particles to the substrate during self-assembly. The 532 nm second harmonic wavelength beam of the pulsed Nd:YAG laser (1064 nm) with a pulse width of 10 ns was used for the removal of individual colloidal particles from the self assembled photonic crystals. In the present tests, the diameter of the laser beam was optically reduced from 7 mm to about 1.8 μm. Controlled line defects and geometrical shapes (e.g., hexagonal and triangle) were created in the 2D arrays in an aqueous medium.


MRS Advances ◽  
2020 ◽  
Vol 5 (64) ◽  
pp. 3507-3520
Author(s):  
Chunhui Dai ◽  
Kriti Agarwal ◽  
Jeong-Hyun Cho

AbstractNanoscale self-assembly, as a technique to transform two-dimensional (2D) planar patterns into three-dimensional (3D) nanoscale architectures, has achieved tremendous success in the past decade. However, an assembly process at nanoscale is easily affected by small unavoidable variations in sample conditions and reaction environment, resulting in a low yield. Recently, in-situ monitored self-assembly based on ion and electron irradiation has stood out as a promising candidate to overcome this limitation. The usage of ion and electron beam allows stress generation and real-time observation simultaneously, which significantly enhances the controllability of self-assembly. This enables the realization of various complex 3D nanostructures with a high yield. The additional dimension of the self-assembled 3D nanostructures opens the possibility to explore novel properties that cannot be demonstrated in 2D planar patterns. Here, we present a rapid review on the recent achievements and challenges in nanoscale self-assembly using electron and ion beam techniques, followed by a discussion of the novel optical properties achieved in the self-assembled 3D nanostructures.


2020 ◽  
Author(s):  
Daniel B. Straus ◽  
Robert J. Cava

The design of new chiral materials usually requires stereoselective organic synthesis to create molecules with chiral centers. Less commonly, achiral molecules can self-assemble into chiral materials, despite the absence of intrinsic molecular chirality. Here, we demonstrate the assembly of high-symmetry molecules into a chiral van der Waals structure by synthesizing crystals of C<sub>60</sub>(SnI<sub>4</sub>)<sub>2</sub> from icosahedral buckminsterfullerene (C<sub>60</sub>) and tetrahedral SnI4 molecules through spontaneous self-assembly. The SnI<sub>4</sub> tetrahedra template the Sn atoms into a chiral cubic three-connected net of the SrSi<sub>2</sub> type that is held together by van der Waals forces. Our results represent the remarkable emergence of a self-assembled chiral material from two of the most highly symmetric molecules, demonstrating that almost any molecular, nanocrystalline, or engineered precursor can be considered when designing chiral assemblies.


2021 ◽  
Vol 11 (7) ◽  
pp. 3254
Author(s):  
Marco Pisco ◽  
Francesco Galeotti

The realization of advanced optical fiber probes demands the integration of materials and structures on optical fibers with micro- and nanoscale definition. Although researchers often choose complex nanofabrication tools to implement their designs, the migration from proof-of-principle devices to mass production lab-on-fiber devices requires the development of sustainable and reliable technology for cost-effective production. To make it possible, continuous efforts are devoted to applying bottom-up nanofabrication based on self-assembly to decorate the optical fiber with highly ordered photonic structures. The main challenges still pertain to “order” attainment and the limited number of implementable geometries. In this review, we try to shed light on the importance of self-assembled ordered patterns for lab-on-fiber technology. After a brief presentation of the light manipulation possibilities concerned with ordered structures, and of the new prospects offered by aperiodically ordered structures, we briefly recall how the bottom-up approach can be applied to create ordered patterns on the optical fiber. Then, we present un-attempted methodologies, which can enlarge the set of achievable structures, and can potentially improve the yielding rate in finely ordered self-assembled optical fiber probes by eliminating undesired defects and increasing the order by post-processing treatments. Finally, we discuss the available tools to quantify the degree of order in the obtained photonic structures, by suggesting the use of key performance figures of merit in order to systematically evaluate to what extent the pattern is really “ordered”. We hope such a collection of articles and discussion herein could inspire new directions and hint at best practices to fully exploit the benefits inherent to self-organization phenomena leading to ordered systems.


2009 ◽  
Vol 143 ◽  
pp. 345 ◽  
Author(s):  
Aurelie M. Brizard ◽  
Marc C. A. Stuart ◽  
Jan H. van Esch

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