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Under spherical confinement with different conditions, defects of LCs change from bipolar to striped textures, then change into tetrahedral defects.

Colloidal cubic diamond crystals with low-coordinated and staggered structures could display a wide photonic bandgap at low refractive index contrasts, which makes them extremely valuable for photonic applications. However, self-assembly of cubic diamond crystals using simple colloidal building blocks is still considerably challenging, due to their low packing fraction and mechanical instability. Here we propose a new strategy for constructing colloidal cubic diamond crystals through cooperative self-assembly of surface-anisotropic triblock Janus colloids and isotropic colloidal spheres into superlattices. In self-assembly, cooperativity is achieved by tuning the interaction and particle size ratio of colloidal building blocks. The pyrochlore lattice formed by self-assembly of triblock Janus colloids acts as a soft template to direct the packing of colloidal spheres into cubic diamond lattices. Numerical simulations show that this cooperative self-assembly strategy works well in a large range of particle size ratio of these two species. Moreover, photonic band structure calculations reveal that the resulting cubic diamond lattices exhibit wide and complete photonic bandgaps and the width and frequency of the bandgaps can also be easily adjusted by tuning the particle size ratio. Our work will open up a promising avenue toward photonic bandgap materials by cooperative self-assembly employing surface-anisotropic Janus or patchy colloids as a soft template.

Controlling the structural order of nanoparticles (NPs), morphology, and composition is of paramount significance in tailoring the physical properties of nanoassembly. However, the commonly reported symmetrical nanocomposites often suffer an interference or sacrifice of the photophysical properties of the original components. To address this challenge, we developed a novel type of organic-inorganic Janus nanocomposite (JNCP) with an asymmetric architecture, offering unique features such as the precisely controlled localization of components, combined modular optical properties, and independent stimuli. As a proof of concept, JNCPs were prepared by incorporating two photoacoustic (PA) imaging agents, namely an organic semiconducting dye and responsive gold nanoparticles (AuNP) assembly in separate compartments of JNCP. Theoretical simulation results confirmed that the formation mechanism of JNCPs arises from the entropy equilibrium in the system. The AuNP assembly generated a PA images with the variation of pH, while the semiconducting molecule served as an internal PA standard agent, leading to ratiometric PA imaging of pH. JNCP based probe holds great potential for real-time and accurate detection of diverse biological targets in living systems.

Multiple highly-ordered 2D crystal structures, including a triangular lattice, kagome lattice, and even a Frank–Kasper σ phase, are found within the layers of bilayered lamellae self-assembled directly from 3D systems of soft Janus particles.

Using simple achiral building blocks modulated by an external field to achieve chiral liquid crystal phases remains a challenge. In this study, a chiral helix liquid crystal phase is obtained for a simple Gay-Berne ellipsoid model under an alternating external field by using molecular dynamics simulations. Our results show that the chiral helix liquid crystal phase can be observed in a wide range of external field strengths when the oscillation period is smaller than the rotational characteristic diffusion timescale of ellipsoids. In addition, we find that the pitch and tilt angle of the helix structure can also be adjusted by changing the strength and oscillation period of the applied alternating external field. This may provide a feasible route for the regulation of chiral liquid crystal phases by an alternating external field.

Probing the transformation from crystalline form II with 11/3 helical structure to form I with 3/1 helical structure in PB-1 and its nanocomposites is of great importance in both scientific fields and commercial applications. The influence of lamellar thickness on the transformation from form II to form I in isotactic polybutylene-1 (PB-1)/carbon nanotube (CNT) nanocomposites was investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) techniques. The crystallization kinetics of PB-1/CNT nanocomposites at different isothermal temperatures (Tc) indicates that CNTs significantly accelerate the nucleation and growth of form II, acting as heterogeneous nucleating agents. However, the influence of CNTs on the form II–I transformation strongly depends on the lamellar thickness obtained at different Tc, verified by the change in melting point (Tm) and the SAXS results for form I. The addition of CNTs accelerates the transformation and elevates the Tm of form I when the Tc is lower than ∼88 °C, and slows the transformation and slightly decreases the Tm when the Tc is higher than ∼88 °C. This is probably due to the fact that the incorporation of CNTs facilitates an increase in lamellar thickness of form II formed at lower Tc but decreases the lamellar thickness of form II formed at higher Tc. Our study illustrates that the lamellar thickness is one of the key points to determine the transformation from form II to form I in PB-1.

Synthetic vesicles of amphiphilic Janus dendrimers are known as dendrimersomes. The understanding of the conditions and formation mechanism of dendrimersomes is meaningful for further controlling the structures. Herein, the characteristics of the self-assembly of amphiphilic Janus dendrimer/water solutions into unilamellar and onion-like dendrimersomes are studied by molecular dynamics simulations via a spherical single-site Janus particle model. The model with two distinct surfaces, one hydrophobic side and another hydrophilic side, describes the amphiphilic nature of Janus dendrimers. By reducing the dendrimers with complex architectures to be simple Janus particles, we investigate the concentration-dependent self-assembled structures as well as the enthalpy-driven formation process of onion-like dendrimersomes, in contrast to the entropy-mediated self-assembly of amphiphilic flexible chains. Three typical equilibrium morphologies including linear micelles, lamellar structures and vesicles are found upon varying the Janus balance and dendrimer concentration. It is observed that the dendrimersomes consisting of the dendrimers with neglectable molecular configuration entropy become very stable, which agrees well with experimental observation. Specifically, different from many lipidsomes and polymersomes which can spontaneously merge, the size of dendrimersomes will not increase through mutual fusion once the well-defined onion-like structure is formed. Moreover, the discharge of water is achieved by water diffusion in our simulations, instead of in the "peeling-one-onion-layer-at-a-time" fashion. Our study combined with the previous ones using flexible chain models could depict a complete picture of dendrimersomes in favor of their applications in drug and gene delivery.

Tert-butyl-substituted tetramethylcyclopentadiene [C5HMe 4 Bu] was reacted with Ru3(CO)12 to prepare [(η5-C5Me 4 Bu)Ru(CO)(μ-CO)]2. The complex was characterized by IR, 1H NMR, 13C NMR, elemental analysis, and single-crystal X-ray diffraction. The complex was investigated as a catalyst in the aerobic oxidation of alcohols to the corresponding aldehydes and ketones in the presence of 2,2’,6,6’-tetramethylpiperidine N-oxide (TEMPO) as co-oxidant. The combination of [(η5-C5Me 4 Bu)Ru(CO)(μ-CO)]2 and TEMPO afforded an efficient catalytic system for the aerobic oxidation of a variety of primary and secondary alcohols, giving the corresponding carbonyl compounds in good-to-excellent yields.

Reactions of the substituted tetramethylcyclopentadienes [C5HMe4R] [R = t Bu, Ph, CH2CH2C(CH3)3] with Mo(CO)3(CH3CN)3 in refluxing xylene gave a series of dinuclear molybdenum carbonyl complexes [(η5-C5Me4R)Mo(CO)3]2 [R = t Bu (1), Ph (2), CH2CH2C(CH3)3 (3)], [(η5-C5Me t Bu)Mo(μ-CO)2]2 (4)], and [(η5-C5Me4) t Bu]2Mo2O4(μ-O) (5)], respectively. Complexes 1–5 were characterized by elemental analysis, IR, 1H NMR, and 13C NMR spectroscopy. In addition, their crystal structures were determined by X-ray crystal diffraction analysis. The catalytic activities of complexes 1–3 in Friedel–Crafts acylation in the presence of o-chloranil has also been investigated; the reactions were achieved under mild conditions to give the corresponding products in moderate yields.

We describe the algorithm of employing multi-GPU power on the basis of Message Passing Interface (MPI) domain decomposition in a molecular dynamics code, GALAMOST, which is designed for the coarse-...

Hollow polyhedral cages hold great potential for application in nanotechnological and biomedical fields. Understanding the formation mechanism of these self-assembled structures could provide guidance for the rational design of the desired polyhedral cages. Here, by constructing kinetic network models from extensive coarse-grained molecular dynamics simulations, we elucidated the formation mechanism of the dodecahedral cage, which is formed by the self-assembly of patchy particles. We found that the dodecahedral cage is formed through increasing the aggregate size followed by structure rearrangement. Based on this mechanistic understanding, we improved the productivity of the dodecahedral cage through the rational design of the patch arrangement of patchy particles, which promotes the structural rearrangement process. Our results demonstrate that it should be a feasible strategy to achieve the rational design of the desired nanostructures via the kinetic analysis. We anticipate that this methodology could be extended to other self-assembly systems for the fabrication of functional nanomaterials.

The design and discovery of new two-dimensional materials with desired structures and properties are always one of the most fundamental goals in materials science. Here we present an atom-mimicking design concept to achieve direct self-assembly of two-dimensional low-coordinated open lattices using three-dimensional patchy particle systems. Besides honeycomb lattices, a new type of two-dimensional square-octagon lattice is obtained through rational design of the patch configuration of soft three-patch particles. However, unexpectedly the building blocks with thermodynamically favoured patch configuration cannot form square-octagon lattices in our simulations. We further reveal the kinetic mechanisms controlling the formation of the honeycomb and square-octagon lattices. The results indicate that the kinetically favoured intermediates play a critical role in determining the structure of obtained open lattices. This kinetics-controlled design principle provides a particularly effective and extendable framework to construct other novel open lattice structures.

A series of six alkyl-substituted tetramethylcyclopentadienyl mononuclear metal carbonyl complexes [(η 5-C5Me4R)Re(CO)3] [R = allyl (1), i-Pr (2), n-butyl (3), t-butyl (4), benzyl (5), CH(CH2)4 (6)] have been synthesized by treating the corresponding ligands (C5Me4R) [R = allyl, i-Pr, n-butyl, t-butyl, benzyl, CH(CH2)4] with Re2(CO)10 in refluxing xylene. The six new complexes were characterized by elemental analysis, IR, 1H NMR and 13C NMR spectroscopy. The crystal structures of all six complexes were determined by X-ray crystal diffraction analysis, showing that they have similar molecular structures, being mononuclear carbonyl complexes. In each of these complexes, the Re atom is η 5 -coordinated to the cyclopentadienyl ring. Complexes 1–5 have significant catalytic activity in Friedel–Crafts reactions of aromatic compounds with alkylation reagents. Compared with traditional catalysts, these mononuclear rhenium carbonyl complexes have obvious advantages such as lower amounts of catalyst, mild reaction conditions and environmentally friendly chemistry.

Because of the unique architectures and promising potential applications of biomimetic helical structures in biotechnology and nanotechnology, the design and fabrication of these structures by experimentally realizable anisotropic colloidal particles remain one of the most challenging tasks in materials science. Here we show how soft Janus particles self-assemble into supracolloidal helices with distinctive structural characteristics, including single helices, double helices, and Bernal spirals, by appropriately tuning the particle softness. We further examine the kinetic mechanisms governing the formation of different helical structures by using particle-based dynamics simulations. Our results provide a new way for experimentally fabricating structure-controllable supracolloidal helices solely from the self-assembly of soft Janus particles.

Molecular dynamics simulations are useful tools to unveil molecular mechanisms of polymer phase separation, self-assembly, adsorption, and so on. Due to large molecular size and slow relaxation of the polymer chains, a great amount of issues related to large-distance chain displacement cannot be tackled easily with conventional molecular dynamic simulations. Systematic coarse-graining and enhanced sampling methods are two types of improvements that can boost spatiotemporal scales in polymer simulations. We present two typical ways to obtain the coarse-graining potential either by fitting to correct liquid structures or by fitting to available thermodynamic properties of polymer systems. The newly proposed anisotropic coarse-grained particle model can be used to describe aggregation and assembly of polymeric building blocks from disk-like micelles to Janus particles. We also present a stochastic polymerization model combined with coarse-grained simulations to investigate the problems strongly influenced by the coupling of polymerization and excluded volume effects. Finally, a facile implementation of integrated tempering sampling method is illustrated to be very efficient on bypassing local energy minima and having access to true equilibrium polymer structures.

How to create novel desired structures by rational design of building blocks represents a significant challenge in materials science. Here we report a conceptually new design principle for creating supracolloidal fullerene-like cages through the self-assembly of soft patchy particles interacting via directional nonbonded interactions by mimicking non-planar sp2 hybridized carbon atoms in C60. Our numerical investigations demonstrate that the rational design of patch configuration, size, and interaction can drive soft three-patch particles to reversibly self-assemble into a vast collection of supracolloidal fullerene-like cages. We further elucidate the formation mechanisms of supracolloidal fullerene-like cages by analyzing the structural characteristics and the formation process. Our results provide conceptual and practical guidance towards the experimental realization of supracolloidal fullerene-like cages, as well as a new perspective on understanding the fullerene formation mechanisms.

A novel mesoscopic simulation method is adopted to study the ordered packing of the anisotropic disklike particles with a soft repulsive interaction, which possesses a modified anisotropic conservative force type used in dissipative particle dynamics. We examine the influence of the shape of the particles, the angular width of the repulsion, and the strength of the repulsion on the packing structures. Specifically, an ordered hexagonal columnar structure is obtained in our simulations. Our study demonstrates that an anisotropic repulsive potential between soft discoidal particles is sufficient to produce a relatively ordered hexagonal columnar structure.

Molecular dynamics simulations are adopted to calculate the equation of state characteristic parameters P*, rho*, and T* of isotactic polypropylene (iPP) and poly(ethylene-co-octene) (PEOC), which can be further used in the Sanchez-Lacombe lattice fluid theory (SLLFT) to describe the respective physical properties. The calculated T* is a function of the temperature, which was also found in the literature. To solve this problem, we propose a Boltzmann fitting of the data and obtain T* at the high-temperature limit. With these characteristic parameters, the pressure-volume-temperature (PVT) data of iPP and PEOC are predicted by the SLLFT equation of state. To justify the correctness of our results, we also obtain the PVT data for iPP and PEOC by experiments. Good agreement is found between the two sets of data. By integrating the Euler-Lagrange equation and the Cahn-Hilliard relation, we predict the density profiles and the surface tensions for iPP and PEOC, respectively. Furthermore, a recursive method is proposed to obtain the characteristic interaction energy parameter between iPP and PEOC. This method, which does not require fitting to the experimental phase equilibrium data, suggests an alternative way to predict the phase diagrams that are not easily obtained in experiments. As an example, in the framework of SLLFT, the spinodal curve for the iPP/PEOC blend is predicted at the low molecular weights that are used in the simulations.

Patchy particles are a type of colloidal particles with one or more well-defined patches on the surfaces. The patchy particles with multiple compositions and functionalities have found wide applications from the fundamental studies to practical uses. In this research patchy micelles with thiol groups in the patches were prepared based on coassembly of free block copolymer chains and block copolymer brushes on silica particles. Thiol-terminated and cyanoisopropyl-capped polystyrene-block-poly(N-isopropylacrylamide) block copolymers (PS-b-PNIPAM-SH and PS-b-PNIPAM-CIP) were synthesized by reversible addition-fragmentation chain transfer polymerization and chemical modifications. Pyridyl disulfide-functionalized silica particles (SiO2-SS-Py) were prepared by four-step surface chemical reactions. PS-b-PNIPAM brushes on silica particles were prepared by thiol-disulfide exchange reaction between PS-b-PNIPAM-SH and SiO2-SS-Py. Surface micelles on silica particles were prepared by coassembly of PS-b-PNIPAM-CIP and block copolymer brushes. Upon cleavage of the surface micelles from silica particles, patchy micelles with thiol groups in the patches were obtained. Dynamic light scattering, transmission electron microscopy, and zeta-potential measurements demonstrate the preparation of patchy micelles. Gold nanoparticles can be anchored onto the patchy micelles through S-Au bonds, and asymmetric hybrid structures are formed. The thiol groups can be oxidized to disulfides, which results in directional assembly of the patchy micelles. The self-assembly behavior of the patchy micelles was studied experimentally and by computer simulation.

We develop a mesoscale nonequilibrium simulation model to study the effect of steady shear on the hierarchical self-assembly of soft disklike particles in dilute solutions. By properly tuning shear rates and solvent conditions, soft disklike particles can self-assemble into flexible threads and bundle-like structures along the flow direction. Shear flow facilitates the self-assembly of soft disklike particles into one-dimensional long threads along the flow direction; however, it suppresses the formation of flexible bundles from the threads while decreasing the solvent quality. The relatively well-defined bundle structures along the flow direction can only be obtained when the solvent condition becomes even worse. Our study elucidates how the solvent condition and shear rate can be utilized to control the shear-induced self-assembled structures, which would enable designed nanofabrication.