Activity-driven polymer knotting for macromolecular topology engineering.

Macromolecules can gain special properties by adopting knotted conformations, but engineering knotted macromolecules is a challenging task. Here, we unexpectedly find that knots can be efficiently generated in active polymer systems. When one end of an actively reptative polymer is anchored, it undergoes continual self-knotting as a result of intermittent giant conformation fluctuations and the outward reptative motion.

Transformable Superisostatic Crystals Self-Assembled from Segment Colloidal Rods.

Transformable mechanical structures can switch between distinct mechanical states. Whether this kind of structure can be self-assembled from simple building blocks at microscale is a question to be answered. In this work, we propose a self-assembly strategy for these structures based on a nematic monolayer of segmented colloidal rods with lateral cutting.

Facilitated dynamics of an active polymer in 2D crowded environments with obstacles.

Understanding the behaviors of a single active chain in complex environments is not only an interesting topic in non-equilibrium physics but also has applicative implications in biological/medical engineering. In this work, by using molecular simulations, we systematically study the dynamical and conformational behaviors of an active polymer in crowded environments, , a single active chain confined in 2D space with randomly arranged obstacles. We found that the competition between the chain's activity and rigidity in the presence of obstacles leads to many interesting dynamical and conformational states, such as the diffusive expanded state, the diffusive collapsed state, and the localized collapsed state.

Duality, Hidden Symmetry, and Dynamic Isomerism in 2D Hinge Structures.

Recently, a new type of duality was reported in some deformable mechanical networks that exhibit Kramers-like degeneracy in phononic spectrum at the self-dual point. In this work, we clarify the origin of this duality and propose a design principle of 2D self-dual structures with arbitrary complexity. We find that this duality originates from the partial central inversion (PCI) symmetry of the hinge, which belongs to a more general end-fixed scaling transformation.

Self-Assembly of Isostatic Self-Dual Colloidal Crystals.

Self-dual structures whose dual counterparts are themselves possess unique hidden symmetry, beyond the description of classical spatial symmetry groups. Here we propose a strategy based on a nematic monolayer of attractive half-cylindrical colloids to self-assemble these exotic structures. This system can be seen as a 2D system of semidisks.

Barrier-controlled nonequilibrium criticality in reactive particle systems.

Nonequilibrium critical phenomena generally exist in many dynamic systems, like chemical reactions and some driven-dissipative reactive particle systems. Here, by using computer simulation and theoretical analysis, we demonstrate the crucial role of the activation barrier on the criticality of dynamic phase transitions in a minimal reactive hard-sphere model. We find that at zero thermal noise, with increasing the activation barrier, the type of transition changes from a continuous conserved directed percolation into a discontinuous dynamic transition by crossing a tricritical point.

Entropy-controlled cross-linking in linker-mediated vitrimers.

Recently developed linker-mediated vitrimers based on metathesis of dioxaborolanes with various commercially available polymers have shown both good processability and outstanding performance, such as mechanical, thermal, and chemical resistance, suggesting new ways of processing cross-linked polymers in industry, of which the design principle remains unknown [M. Röttger , 356, 62-65 (2017)]. Here we formulate a theoretical framework to elucidate the phase behavior of the linker-mediated vitrimers, in which entropy plays a governing role.

Hierarchical glass transition of hard hemidisks with local assemblies.

Using computer simulation, we investigate the glass transition of a two-dimensional hard-hemidisk system. Upon increasing the packing fraction of the system, we find that the system vitrifies into a glass with local assembled discal "dimers", which are free to rotate in a collective way. The rotational mean square displacement does not exhibit the typical plateau (slowdown) like what occurs in the translational mean square displacement.

Supercrystallographic Reconstruction of 3D Nanorod Assembly with Collectively Anisotropic Upconversion Fluorescence.

Constructing three-dimensional (3D) metamaterials from functional nanoparticles endows them with emerging collective properties tailored by the packing geometries. Herein, we report 3D supercrystals self-assembled from upconversion nanorods (NaYF:Yb,Er NRs), which exhibit both translational ordering of NRs and orientational ordering between constituent NRs in the superlattice (SL). The construction of 3D reciprocal space mappings (RSMs) based on synchrotron-based X-ray scattering measurements was developed to uncover the complex structure of such an assembly.

Mechanical Tolerance of Cascade Bioreactions via Adaptive Curvature Engineering for Epidermal Bioelectronics.

Epidermal bioelectronics that can monitor human health status non-invasively and in real time are core to wearable healthcare equipment. Achieving mechanically tolerant surface bioreactions that convert biochemical information to detectable signals is crucial for obtaining high sensing fidelity. In this work, by combining simulations and experiments, a typical epidermal biosensor system is investigated based on a redox enzyme cascade reaction (RECR) comprising glucose oxidase/lactate oxidase enzymes and Prussian blue nanoparticles.

Thermal-Disrupting Interface Mitigates Intercellular Cohesion Loss for Accurate Topical Antibacterial Therapy.

Bacterial infections remain a leading threat to global health because of the misuse of antibiotics and the rise in drug-resistant pathogens. Although several strategies such as photothermal therapy and magneto-thermal therapy can suppress bacterial infections, excessive heat often damages host cells and lengthens the healing time. Here, a localized thermal managing strategy, thermal-disrupting interface induced mitigation (TRIM), is reported, to minimize intercellular cohesion loss for accurate antibacterial therapy.

Hydrodynamics of random-organizing hyperuniform fluids.

Disordered hyperuniform structures are locally random while uniform like crystals at large length scales. Recently, an exotic hyperuniform fluid state was found in several nonequilibrium systems, while the underlying physics remains unknown. In this work, we propose a nonequilibrium (driven-dissipative) hard-sphere model and formulate a hydrodynamic theory based on Navier-Stokes equations to uncover the general mechanism of the fluidic hyperuniformity (HU).

Self-assembled multi-layer simple cubic photonic crystals of oppositely charged colloids in confinement.

Designing and fabricating self-assembled open colloidal crystals have become one major direction in the soft matter community because of many promising applications associated with open colloidal crystals. However, most of the self-assembled crystals found in experiments are not open but close-packed. Here, by using computer simulation, we systematically investigate the self-assembly of oppositely charged colloidal hard spheres confined between two parallel hard walls, and we find that the confinement can stabilize multi-layer NaCl-like (simple cubic) open crystals.

Nonequilibrium strongly hyperuniform fluids of circle active particles with large local density fluctuations.

Disordered hyperuniform structures are an exotic state of matter having vanishing long-wavelength density fluctuations similar to perfect crystals but without long-range order. Although its importance in materials science has been brought to the fore in past decades, the rational design of experimentally realizable disordered strongly hyperuniform microstructures remains challenging. Here we find a new type of nonequilibrium fluid with strong hyperuniformity in two-dimensional systems of chiral active particles, where particles perform independent circular motions of the radius with the same handedness.

Correction: Driving dynamic colloidal assembly using eccentric self-propelled colloids.

Correction for 'Driving dynamic colloidal assembly using eccentric self-propelled colloids' by Zhan Ma et al., Soft Matter, 2017, 13, 8940-8946.

Self-Assembled Chiral Photonic Crystals from a Colloidal Helix Racemate.

Chiral crystals consisting of microhelices have many optical properties, while presently available fabrication processes limit their large-scale applications in photonic devices. Here, by using a simplified simulation method, we investigate a bottom-up self-assembly route to build up helical crystals from the smectic monolayer of a colloidal helix racemate. With increasing the density, the system undergoes an entropy-driven cocrystallization by forming crystals of various symmetries with different helical shapes.

Three-Dimensional Non-Close-Packed Structures of Oppositely Charged Colloids Driven by pH Oscillation.

The implementation of non-close-packed structures in colloids is challenging. Using Brownian dynamics simulations, we study the nonequilibrium self-assembly in suspensions of oppositely charged particles, whose charge magnitude is responsive to the pH of the solution. Under the fast pH-oscillating condition, various non-close-packed (e.

Driving dynamic colloidal assembly using eccentric self-propelled colloids.

Designing protocols to dynamically direct the self-assembly of colloidal particles has become an important direction in soft matter physics because of promising applications in the fabrication of dynamic responsive functional materials. Here, using computer simulations, we found that in the mixture of passive colloids and eccentric self-propelled active particles, when the eccentricity and self-propulsion of active particles are high enough, the eccentric active particles can push passive colloids to form a large dense dynamic cluster, and the system undergoes a novel dynamic demixing transition. Our simulations show that the dynamic demixing occurs when the eccentric active particles move much faster than the passive particles such that the dynamic trajectories of different active particles can overlap each other while passive particles are depleted from the dynamic trajectories of active particles.

Complexation of Polyelectrolytes with Hydrophobic Drug Molecules in Salt-Free Solution: Theory and Simulations.

The delivery and dissolution of poorly soluble drugs is challenging in the pharmaceutical industry. One way to significantly improve the delivery efficiency is to incorporate these hydrophobic small molecules into a colloidal polyelectrolyes(PE)-drug complex in their ionized states. Despite its huge application value, the general mechanism of PE collapse and complex formation in this system has not been well understood.

Modeling Stretching-Induced Immiscibility in Nonmonodisperse Polymer Systems.

The behavior of polymer chains under stretching is a classical problem in polymer science. However, a fundamental question still in mist is how the stretching affects the interactions between polymer chains, especially when the tensions on the chains are unequal. In this work, we combine statistical theory and molecular simulations to study the influence of this tension disparity on the miscibility of athermal polymer systems.

Crowding-induced cooperativity in DNA surface hybridization.

High density DNA brush is not only used to model cellular crowding, but also has a wide application in DNA-functionalized materials. Experiments have shown complicated cooperative hybridization/melting phenomena in these systems, raising the question that how molecular crowding influences DNA hybridization. In this work, a theoretical modeling including all possible inter and intramolecular interactions, as well as molecular details for different species, is proposed.